https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Medicine/Translation_task_force/RTT/Simple_Obesity
https://en.wikipedia.org/wiki/Obesity
{{Infobox disease
|Name = 肥胖
|Image = Obesity-waist circumference.svg
|Alt = 描繪三種人體體型輪廓的描繪圖，由左至右分別為正常、過重與肥胖體型。
|Caption = 正常、過重與肥胖腰圍的輪廓圖
|DiseasesDB = 9099
|ICD10 = {{ICD10|E|66| |e|65}}
|ICD9 = {{ICD9|278}}
|MedlinePlus = 007297
|OMIM = 601665
|eMedicineSubj = med
|eMedicineTopic = 1653
|MeshName = Obesity
|MeshNumber = C23.888.144.699.500
|
}}
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a negative effect on health, leading to reduced life expectancy and/or increased health problems.[1][2] In Western countries, people are considered obese when their body mass index (BMI),[3] a measurement obtained by dividing a person’s weight by the square of the person’s height, exceeds 30 kg/m2, with the range 25-30 kg/m2 defined as overweight. Some East Asian countries use stricter criteria.
’’’肥胖’’’（{{lang|en|Obesity}}）是一種醫學定義，描述過多體脂肪累積到一定程度後，對健康可能造成負面效應；引起平均壽命減短及健康問題增加[1][2]。肥胖的標準常使用[[身體質量指數|身高體重指數]]（{{lang|en|BMI}}）來計算，即以測量的體重（公斤）除以身高（公尺）的平方[3]。西方人認為的肥胖大於30公斤/平方公尺，而過重標準則是介於25到30公斤/平方公尺間。在台灣，[[行政院衛生署]]（今[[衛生福利部]]）根據其相關研究，於2002年4月公布台灣成人肥胖標準：{{lang|en|BMI}}＜18.5 為過輕，18.5≦{{lang|en|BMI}}＜24 為正常體重，24≦{{lang|en|BMI}}＜27 為過重，{{lang|en|BMI}}≧27 即為肥胖[身4][身5] 。但幼兒並不適合用成人的{{lang|en|BMI}}標準來評量。
Obesity increases the likelihood of various diseases, particularly heart disease, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis.[2] Obesity is most commonly caused by a combination of excessive food energy intake, lack of physical activity, and genetic susceptibility, although a few cases are caused primarily by genes, endocrine disorders, medications, or psychiatric illness. Evidence to support the view that some obese people eat little yet gain weight due to a slow metabolism is limited. On average, obese people have a greater energy expenditure than their thin counterparts due to the energy required to maintain an increased body mass.[4][5]
肥胖會增加[[心血管疾病]]、[[第二型糖尿病]]、[[睡眠呼吸中止症]]、某些[[癌症]]、[[退化性關節炎]]及其他疾病的發生機會[2]。而造成肥胖的主因通常包括攝取過多[[熱量]]、欠缺[[運動]]及體質問題等。其他像是基因疾病、內分泌異常、藥物影響及精神疾病也可能造成肥胖。目前的科學證據傾向不支持「肥胖是由於[[代謝]]率較低，消耗能量速度慢，因此即使吃得不多也越來越胖」的說法。一般而言，由於肥胖的人需要花費更多能量維持較重的體重，他們的代謝率反而高於常人[4][5]。
Dieting and exercising are the main treatments for obesity. Diet quality can be improved by reducing the consumption of energy-dense foods, such as those high in fat and sugars, and by increasing the intake of dietary fiber. With a suitable diet, anti-obesity drugs may be taken to reduce appetite or decrease fat absorption. If diet, exercise, and medication are not effective, a gastric balloon may assist with weight loss, or surgery may be performed to reduce stomach volume and/or bowel length, leading to feeling full earlier and a reduced ability to absorb nutrients from food.[6][7]
肥胖的主要治療方式包括飲食計畫和運動。透過減少攝取高熱量食物（高油高糖食物）與增加高[[膳食纖維|纖]]食物的比例，進而調整患者的日常飲食，如果飲食狀況已經受到良好的控制但卻仍無法有效減重，則可能考慮搭配藥物來減低食慾與脂肪吸收。如果飲食、運動、甚至搭配藥物都不見效，以胃內水球置放術減少胃容積可能會有幫助，以手術來減少胃容積或腸道長度也能直接使食量減少並減少營養素的吸收[6][7]。
Obesity is a leading preventable cause of death worldwide, with increasing rates in adults and children. Authorities view it as one of the most serious public health problems of the 21st century.[8] Obesity is stigmatized in much of the modern world (particularly in the Western world), though it was widely seen as a symbol of wealth and fertility at other times in history and still is in some parts of the world.[2][9] In 2013, the American Medical Association classified obesity as a disease.[10][11]
肥胖是世界上最常見的可預防死因之一，而且在成人與兒童的盛行率都在上升。專家認為它是21世紀最重要的公共衛生問題[8]。在歷史上肥胖常被視為財富與多產的象徵，在部分國家直到今日都仍保有這樣的意義，但在現代社會（尤其是西方國家）肥胖已經被汙名化了[2][9]。2013年，美國醫學會將肥胖定義為一種疾病[10][11]。
Classification
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health.[1] It is defined by body mass index (BMI) and further evaluated in terms of fat distribution via the waist–hip ratio and total cardiovascular risk factors.[12][13] BMI is closely related to both percentage body fat and total body fat.[14]
肥胖是描述一種生理狀態，指的是體脂肪過度堆積而對健康造成負面影響[1]。肥胖的定義初步來自[[身體質量指數]]（{{lang|en|Body Mass Index, BMI}}），並進一步由測量[[腰臀比]]來評估體脂分布、以及評估其他的心血管症病風險因子[12][13]。[[身體質量指數]]與體脂肪比率與體脂肪總量都密切相關。
In children, a healthy weight varies with age and sex. Obesity in children and adolescents is defined not as an absolute number but in relation to a historical normal group, such that obesity is a BMI greater than the 95th percentile.[15] The reference data on which these percentiles were based date from 1963 to 1994, and thus have not been affected by the recent increases in weight.[16]
兒童的健康體重因性別與年齡而有不同的標準，因此兒童與青少年的肥胖並沒有單一的標準，而是透過與同年齡性別的其他孩子（常模）比較來決定。舉例而言，兒童與青少年的肥胖定義是[[身體質量指數]]高於95%的同儕（95百分位以上[15]）。用於決定兒童與青少年肥胖與否的常模資料來自1963年至1994年，因此並沒有反映近年平均體重的上升[16]。
BMI is defined as the subject’s weight divided by the square of their height and is calculated as follows.
\\mathrm{BMI}= \\frac{m}{h^2},
where m and h are the subject’s weight and height respectively.
BMI is usually expressed in kilograms per square metre, resulting when weight is measured in kilograms and height in metres. To convert from pounds per square inch multiply by 703 (kg/m2)/(lb/sq in).[18]
[[身體質量指數]]的定義是體重（以公斤計）除以身高的平方（以公尺計）。
\\mathrm{BMI}= \\frac{m}{h^2}
式子中的m是體重，而h是身高。
[[身體質量指數]]通常以公斤/平方公尺為單位，如果以英制單位（磅與吋）計算，則應該再乘以703(公斤/平方公尺)/(磅/平方吋)[18]。
The most commonly used definitions, established by the World Health Organization (WHO) in 1997 and published in 2000, provide the values listed in the table at right.[3]
最常用的肥胖標準是由[[世界衛生組織]]於1997年制訂並於2000年發表，詳見右方表格[3]。
Some modifications to the WHO definitions have been made by particular bodies. The surgical literature breaks down "class III" obesity into further categories whose exact values are still disputed.[19]
有些組織則對世界衛生組織的肥胖標準做了一些修正，比方說外科文獻上通常將「第三級肥胖」再做細分，細分的標準則依研究者而有所不同，目前還沒有定論[19]。
Any BMI ≥ 35 or 40 kg/m2 is severe obesity.
A BMI of ≥ 35 kg/m2 and experiencing obesity-related health conditions or ≥40–44.9 kg/m2 is morbid obesity.
A BMI of ≥ 45 or 50 kg/m2 is super obesity.
As Asian populations develop negative health consequences at a lower BMI than Caucasians, some nations have redefined obesity; the Japanese have defined obesity as any BMI greater than 25 kg/m2[20] while China uses a BMI of greater than 28 kg/m2.[21]
[[身體質量指數]]大於35或40公斤/平方公尺者為嚴重肥胖。
[[身體質量指數]]大於35公斤/平方公尺並患有肥胖相關健康問題者，或是身體質量指數大於40-44.9公斤/平方公尺者為病態肥胖。
[[身體質殘指數]]大於45或50公斤/平方公尺者為極度肥胖。
由於亞洲人相對於[[高加索人種]]而言，在較低的身體質量指數時就會開始出現健康問題，因此部分國家據此修正國內的肥胖定義。台灣將肥胖定義為身體質量指數大於27公斤/平方公尺；日本為大於25公斤/平方公尺；中國則將身體質量指數大於28公斤/平方公尺者定義為肥胖[21]。
Effects on health
Excessive body weight is associated with various diseases, particularly cardiovascular diseases, diabetes mellitus type 2, obstructive sleep apnea, certain types of cancer, osteoarthritis[2] and asthma.[2][22] As a result, obesity has been found to reduce life expectancy.[2]
體重過重與許多疾病的發生相關。包括[[心血管疾病]]、[[第二型糖尿病]]、[[睡眠呼吸中止症]]、某些[[癌]]症、[[退化性關節炎]]、以及[[氣喘]][2][22]。因為與疾病的關聯性，研究也顯示肥胖者的預期餘命縮短[2]。
死亡率
Mortality
Obesity is one of the leading preventable causes of death worldwide.[8][24][25] Large-scale American and European studies have found that mortality risk is lowest at a BMI of 20–25 kg/m2[23][26] in non-smokers and at 24–27 kg/m2 in current smokers, with risk increasing along with changes in either direction.[27][28] In Asians risk begins to increase between 22–25 kg/m2.[29] A BMI above 32 kg/m2 has been associated with a doubled mortality rate among women over a 16-year period.[30] In the United States obesity is estimated to cause 111,909 to 365,000 deaths per year,[2][25] while 1 million (7.7%) of deaths in Europe are attributed to excess weight.[31][32] On average, obesity reduces life expectancy by six to seven years,[2][33] a BMI of 30–35 kg/m2 reduces life expectancy by two to four years,[26] while severe obesity (BMI > 40 kg/m2) reduces life expectancy by ten years.[26]
肥胖是世界上最常見的可預防死因[8][24][25]。歐美的大規模研究指出[[身體質量指數]]介於20到25公斤/平方公尺的非吸[[菸]]者[23][26]以及身體質量指數介於24-27公斤/平方公尺的吸菸者分別有最低的死亡風險，身體質量指數不論是高於或低於這個範圍，死亡風險都會開始上升[27][28]。在亞洲人身上，死亡風險則在身體質量指數達22到25公斤/平方公尺間就開始上升[29]。身體質量指數大於32公斤/平方公尺的女性的十六年間死亡率高達常人兩倍[30]。在美國，肥胖每年帶走111,909至365,000條生命[2][25]，在歐洲，有7.7%的死亡和過重相關，這相當於100萬條生命[31][32]。平均而言，肥胖會減少6-7年的餘命[2][33]，而當一個人的身體質量指數達到30-35公斤/平方公尺間時，餘命會減少2-4年[26]，而嚴重肥胖（身體質量指數大於40公斤/平方公尺）則會減少十年餘命[26]。
致病率
Morbidity
Obesity increases the risk of many physical and mental conditions. These comorbidities are most commonly shown in metabolic syndrome,[2] a combination of medical disorders which includes: diabetes mellitus type 2, high blood pressure, high blood cholesterol, and high triglyceride levels.[34]
肥胖會使許多生理與心理疾病的風險上升。疾病與肥胖的共存關係的最好例子是[[代謝症候群]][2]。代謝症候群包括[[第二型糖尿病]]、[[高血壓]]、血中膽固醇過高、血中三酸甘油酯過高等[34]。
Complications are either directly caused by obesity or indirectly related through mechanisms sharing a common cause such as a poor diet or a sedentary lifestyle. The strength of the link between obesity and specific conditions varies. One of the strongest is the link with type 2 diabetes. Excess body fat underlies 64% of cases of diabetes in men and 77% of cases in women.[35]
肥胖的併發症有可能是直接由肥胖造成，或者是與肥胖有共同的原因：比如不健康的飲食或是少動的生活型態({{link-en|坐式生活型態型態|sedentary lifestyle}})。肥胖與不同的疾病間的關聯性強弱不一，和肥胖高度相關的疾病最好的例子是[[第二型糖尿病]]，我們在64%男性糖尿病患與77%的女性糖尿病患身上可以發現體脂肪過度堆積。
Health consequences fall into two broad categories: those attributable to the effects of increased fat mass (such as osteoarthritis, obstructive sleep apnea, social stigmatization) and those due to the increased number of fat cells (diabetes, cancer, cardiovascular disease, non-alcoholic fatty liver disease).[2][36] Increases in body fat alter the body’s response to insulin, potentially leading to insulin resistance. Increased fat also creates a proinflammatory state,[37][38] and a prothrombotic state.[36][39]
肥胖對健康的影響可分為兩大類：第一是體脂肪量增加造成的影響（包括[[退化性關節炎]]、[[睡眠呼吸中止症]]、社交汙名化等）；第二是體內脂肪細胞增加造成的影響（包括[[第二型糖尿病]]、[[癌|癌症]]、[[心血管疾病]]、非酒精性脂肪肝等[2][36]）。體脂肪的增加會改變人體對[[胰島素]]的反應，並造成[[胰島素抵抗|胰島素阻抗]]；高體脂也會使得身體容易產生發炎反應[37][38]，並且更容易形成[[血栓]]。
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-心臟科：冠心症[40](心絞痛與心肌梗塞)、鬱血性心衰竭[2]、高血壓[2]、血脂異常[2]、深部靜脈栓塞與肺栓塞[41]
-皮膚科：肥胖紋[42]、[[黑棘皮症]][42]、淋巴水腫[42]、蜂窩性組織炎[42]、多毛症[42]、對磨疹[43]
-內分泌及生殖醫學科：糖尿病[2]、多囊性卵巢症候群[2]、月經失調[2]、不孕症[2][44]、懷孕中的併發症[2][44]、先天缺陷[2]、子宮內胎兒死亡[44]
-肝膽腸胃科：[[胃食道逆流]][2][45]、[[脂肪肝]][2]、膽汁滯留（[[膽結石]][2]）
-神經科：[[中風]][2]、麻痛性股痛[46]、[[偏頭痛]][47]、[[腕隧道症候群]][48]、[[失智症]][49]、[[自發性顱內壓上升]][50]、[[多發性硬化症]][51]
-腫瘤科[52]：[[食道癌]]、[[大腸直腸癌]]、[[胰臟癌]]、[[膽道癌|膽囊癌]]、[[子宮內膜癌]]、腎臟癌、[[血癌]]、[[黑色素瘤]]
-精神科：女性[[憂鬱症]][2]、社交汙名化[2]
-呼吸相關：[[睡眠呼吸中止症]][2][22]、[[肥胖肺換氣不足綜合症|肥胖換氣不足症候群]][2][22]、[[氣喘]][2][22]、全身麻醉風險上升[2][5]
-骨科與風溼免疫科：[[痛風]][53]、活動性不佳[54]、[[退化性關節炎]][2]、[[下背痛]][55]
-泌尿與腎臟科：[[勃起困難]][56]、[[尿失禁]][57]、[[慢性腎衰竭]][58]、[[性腺功能低下症]][59]、陰莖包埋[60]
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生存矛盾
Survival paradox
Although the negative health consequences of obesity in the general population are well supported by the available evidence, health outcomes in certain subgroups seem to be improved at an increased BMI, a phenomenon known as the obesity survival paradox.[61] The paradox was first described in 1999 in overweight and obese people undergoing hemodialysis,[61] and has subsequently been found in those with heart failure and peripheral artery disease (PAD).[62]
雖然一般人的肥胖對健康造成的負面影響有大量證據支持，在部分族群中身體質量指數的上升卻似乎對健康狀況有幫助。這個現象被稱為「肥胖生存矛盾」[61]，在1999年時首次在過重與肥胖的[[血液透析]]患者身上發現[61]，稍後也在[[心衰竭]]與[[周邊血管疾病]]的患者身上發現[61]。
In people with heart failure, those with a BMI between 30.0 and 34.9 had lower mortality than those with a normal weight. This has been attributed to the fact that people often lose weight as they become progressively more ill.[63] Similar findings have been made in other types of heart disease. People with class I obesity and heart disease do not have greater rates of further heart problems than people of normal weight who also have heart disease. In people with greater degrees of obesity, however, the risk of further cardiovascular events is increased.[64][65] Even after cardiac bypass surgery, no increase in mortality is seen in the overweight and obese.[66] One study found that the improved survival could be explained by the more aggressive treatment obese people receive after a cardiac event.[67] Another found that if one takes into account chronic obstructive pulmonary disease (COPD) in those with PAD, the benefit of obesity no longer exists.[62]
對於患有[[心衰竭]]的人而言，身體質量指數界於30.0-34.9間的人的死亡率比起正常體重的人來得低，這個現象的解釋是心衰竭的患者在病情惡化時通常伴隨著體重的減輕[63]，其他的心臟疾病也能看到相似的現象。一級肥胖的心臟病患者在未來發生其他心臟問題的機會並不比體重正常的心臟病患者來得高，但對於肥胖程度更高的患者來說未來發生其他心血管問題的機會就開始上升[64][65]。即使對接受[[心血管繞道手術]]的患者而言，在肥胖與過重的患者群中的死亡率相對於一般人也沒有上升[66]。研究指出肥胖與過重的患者較預期良好的預後是由於在心臟病發作後，肥胖與過重的患者會得到較為積極的治療[67]，也有研究指出若考慮[[周邊血管疾病]]患者同時患有[[慢性阻塞性肺病]]的狀況，那肥胖對預後的改善就不存在了[62]。
Causes
At an individual level, a combination of excessive food energy intake and a lack of physical activity is thought to explain most cases of obesity.[68] A limited number of cases are due primarily to genetics, medical reasons, or psychiatric illness.[69] In contrast, increasing rates of obesity at a societal level are felt to be due to an easily accessible and palatable diet,[70] increased reliance on cars, and mechanized manufacturing.[71][72]
就個人層面來說，熱量攝取過多與運動不足被認為可以解釋大多數肥胖者發胖的原因[68]，但仍有一小部分肥胖者是由於基因上、醫療上、或是精神疾病上的原因而造成肥胖[69]。另一方面，社群中整體肥胖率的上升則被認為是因為食物變得容易取得並且更為可口[70]，且對於車輛與機械化生產的依賴上升。
A 2006 review identified ten other possible contributors to the recent increase of obesity: (1) insufficient sleep, (2) endocrine disruptors (environmental pollutants that interfere with lipid metabolism), (3) decreased variability in ambient temperature, (4) decreased rates of smoking, because smoking suppresses appetite, (5) increased use of medications that can cause weight gain (e.g., atypical antipsychotics), (6) proportional increases in ethnic and age groups that tend to be heavier, (7) pregnancy at a later age (which may cause susceptibility to obesity in children), (8) epigenetic risk factors passed on generationally, (9) natural selection for higher BMI, and (10) assortative mating leading to increased concentration of obesity risk factors (this would increase the number of obese people by increasing population variance in weight).[73] While there is substantial evidence supporting the influence of these mechanisms on the increased prevalence of obesity, the evidence is still inconclusive, and the authors state that these are probably less influential than the ones discussed in the previous paragraph.
一篇發表於2006年的評論性文章點出另外十個近年肥胖率上升的原因：(1) 睡眠不足、(2) 內分泌干擾因子增加（比方說會干擾脂肪代謝的環境汙染物）、(3) 生活環境的溫度變化率下降、(4) 吸菸率下降（吸菸會抑制食慾）、(5)造成體重上升的藥物使用率增加（例如第二代[[抗精神病藥]]）、(6) 人口組成的改變（平均體重較高的年齡層或種族佔的比例增加）、(7) 懷孕年齡的延後（可能造成兒童更容易肥胖）、(8) 促使發胖的[[表徵遺傳學|表徵遺傳]]因子隨世代累積、(9) 天擇偏好較高的身體質量指數、(10) 偏好具相似特性和背景的擇偶策略使肥胖的危險因子更為集中（這會使肥胖與消瘦的人數都上升，而整體的體重變異也上升）[73]。雖然有許多證據支持這些原因在肥胖的發生中的角色，但這些證據仍然不夠決定性，而作者也認為這些原因對肥胖的影響可能不如上段所談的那些。
飲食
Diet
Dietary energy supply per capita varies markedly between different regions and countries. It has also changed significantly over time.[74] From the early 1970s to the late 1990s the average food energy available per person per day (the amount of food bought) increased in all parts of the world except Eastern Europe. The United States had the highest availability with 3,654 calories (15,290 kJ) per person in 1996.[74] This increased further in 2003 to 3,754 calories (15,710 kJ).[74] During the late 1990s Europeans had 3,394 calories (14,200 kJ) per person, in the developing areas of Asia there were 2,648 calories (11,080 kJ) per person, and in sub-Saharan Africa people had 2,176 calories (9,100 kJ) per person.[74][75] Total food energy consumption has been found to be related to obesity.[76]
人均飲食熱量攝取在不同的區域與國家間有很大的差別，並且隨時間而有明顯改變[74]。從1970年代早期到1990年代晚期，除了東歐地區外，全世界人均每日熱量攝取(購買的食物量)都在上升。1996年，人均每日熱量供應最高的國家是美國，高達3654大卡（15290千焦[74]），這個數字還在持續爬升，到了2003年來到了3754大卡（15710千焦[74]）。1990年代晚期，歐洲人平均每人每日購買3394大卡（14200千焦）的食物，而在亞洲的[發展中國家]每人每日的食物購入量則是2648大卡（11080千焦），在[撒哈拉以南非洲]每人每日的食物購入量是2176大卡（9100千焦）[74][75]。總熱量攝取量與肥胖的發生是相關聯的。
The widespread availability of nutritional guidelines[77] has done little to address the problems of overeating and poor dietary choice.[78] From 1971 to 2000, obesity rates in the United States increased from 14.5% to 30.9%.[79] During the same period, an increase occurred in the average amount of food energy consumed. For women, the average increase was 335 calories (1,400 kJ) per day (1,542 calories (6,450 kJ) in 1971 and 1,877 calories (7,850 kJ) in 2004), while for men the average increase was 168 calories (700 kJ) per day (2,450 calories (10,300 kJ) in 1971 and 2,618 calories (10,950 kJ) in 2004). Most of this extra food energy came from an increase in carbohydrate consumption rather than fat consumption.[80] The primary sources of these extra carbohydrates are sweetened beverages, which now account for almost 25 percent of daily food energy in young adults in America,[81] and potato chips.[82] Consumption of sweetened drinks such as soft drinks, fruit drinks, iced tea, and energy and vitamin water drinks is believed to be contributing to the rising rates of obesity[83][84] and to an increased risk of metabolic syndrome and type 2 diabetes.[85]
即使飲食指引相當普及[77]，但飲食過量與飲食內容不健康的問題卻未因此改善[78]。自1971年到2000年，美國的肥胖率自14.5%爬升到30.9%[79]，而平均的熱量攝取也在同期上升了。對女性而言，每日熱量攝取平均上升了335大卡（1400千焦），自1971年的1542大卡（6450千焦）上升到2004年的1877大卡（7850千焦）。飲食熱量的上升主要來自於[[碳水化合物]]攝取量的上升，而不是[油脂]攝取的上升[80]，而多出來的[[碳水化合物]]主要來自含糖飲料－現在在美國年輕人的飲食中，含糖飲料佔了每日熱量攝取的近四分之一[81]，以及[[馬鈴薯片|洋芋片]][82]。碳酸飲料、調味果汁、調味茶、運動及能量飲品等含糖飲料被認為在肥胖率的上升中居功厥偉[83][84]，並造成[[代謝症候群]]與[[第二型糖尿病]]的風險上升。
As societies become increasingly reliant on energy-dense, big-portions, and fast-food meals, the association between fast-food consumption and obesity becomes more concerning.[86] In the United States consumption of fast-food meals tripled and food energy intake from these meals quadrupled between 1977 and 1995.[87]
隨著社會變得越來越低賴熱量密度高、份量大的速食餐點，速食與肥胖的關聯性變得越來越令人在意[86]。自1977年至1995間，美國的速食食用量成長了三倍，而來自速食的熱量則成長了四倍之多[87]。
Agricultural policy and techniques in the United States and Europe have led to lower food prices. In the United States, subsidization of corn, soy, wheat, and rice through the U.S. farm bill has made the main sources of processed food cheap compared to fruits and vegetables.[88] Calorie count laws and nutrition facts labels attempt to steer people toward making healthier food choices, including awareness of how much food energy is being consumed.
歐美的農業政策與技術使糧食價格下滑。在美國，基於農業法案對玉米、大豆、小麥、以及米的補助是加工食品在價格上低於蔬果的主因[88]。近年國家開始制定熱量標示與食品成份標示的相關法令，希望能使人們選擇較為健康的食物，並提升對自身的熱量攝取的關心。
Obese people consistently under-report their food consumption as compared to people of normal weight.[89] This is supported both by tests of people carried out in a calorimeter room[90] and by direct observation.
相對於正常體重者，肥胖者傾向於將自己的食量說得較低[89]，以熱量計測量受試者的研究與直接的觀察性研究都支持這個現象的存在。
少動的生活型態（{{link-en|坐式生活型態型態|sedentary lifestyle}}）
Sedentary lifestyle
A sedentary lifestyle plays a significant role in obesity.[91] Worldwide there has been a large shift towards less physically demanding work,[92][93][94] and currently at least 30% of the world’s population gets insufficient exercise.[93] This is primarily due to increasing use of mechanized transportation and a greater prevalence of labor-saving technology in the home.[92][93][94] In children, there appear to be declines in levels of physical activity due to less walking and physical education.[95] World trends in active leisure time physical activity are less clear. The World Health Organization indicates people worldwide are taking up less active recreational pursuits, while a study from Finland[96] found an increase and a study from the United States found leisure-time physical activity has not changed significantly.[97]
少動的生活型態（{{link-en|坐式生活型態型態|sedentary lifestyle}}）在肥胖的發生上扮演重要角色[91]。工作的體力需求減少的現象在世界各地都可看到[92][93][94]，而至少有30%的人的生活中沒有進行足夠的運動[93]。這主要是由於在移動時搭乘交通工具的機會增加，而在家中省力的新技術也增加[92][93][94]。運動量下降的現象在兒童身上也能看到，主因是走路的機會變少且體育課的量也下降[95]。人們將休閒時間花在運動的比例是否有下降的趨勢則不那麼明朗。[[世界衛生組織]]指出人們的娛樂活動的體力消耗正在減少，但在芬蘭的一個研究[96]則得到相反的結論，至於在美國的研究則發現美國人的娛樂活動的體力消耗並沒有明顯的變化[97]。
In both children and adults, there is an association between television viewing time and the risk of obesity.[98][99][100] A review found 63 of 73 studies (86%) showed an increased rate of childhood obesity with increased media exposure, with rates increasing proportionally to time spent watching television.[101]
不論在兒童或成人，看電視的時間與肥胖的風險都有關聯[98][99][100]。一篇評論性文章指出在針對兒童肥胖的73個研究中，有63個（86%）都發現對媒體的暴露與兒童肥胖率同步上升，且上升的程度與看電視的時間成比例。
基因
Genetics
Like many other medical conditions, obesity is the result of an interplay between genetic and environmental factors. Polymorphisms in various genes controlling appetite and metabolism predispose to obesity when sufficient food energy is present. As of 2006, more than 41 of these sites on the human genome have been linked to the development of obesity when a favorable environment is present.[103] People with two copies of the FTO gene (fat mass and obesity associated gene) have been found on average to weigh 3–4 kg more and have a 1.67-fold greater risk of obesity compared with those without the risk allele.[104] The differences in BMI between people that are due to genetics varies depending on the population examined from 6% to 85%.[105]
如同許多疾病，肥胖是基因與環境因子互動所產生的結果。控制食慾與代謝的基因們的多型性決定了在面對過多熱量時人有多容易發胖。至2006年為止，在人類基因體上已有超過41個基因被認為與肥胖（當環境適合時）的發生有關[103]。擁有兩套胖基因（{{lang|en|FTO}}基因，脂肪與肥胖關聯基因）的人比起常人平均重了3-4公斤，並且有1.67倍的機會肥胖[104]。可以用基因不同來解釋的身體質量指數差異的比率，依不同族群而定，有6-85%之多[105]。
Obesity is a major feature in several syndromes, such as Prader–Willi syndrome, Bardet–Biedl syndrome, Cohen syndrome, and MOMO syndrome. (The term "non-syndromic obesity" is sometimes used to exclude these conditions.)[106] In people with early-onset severe obesity (defined by an onset before 10 years of age and body mass index over three standard deviations above normal), 7% harbor a single point DNA mutation.[107]
肥胖是幾個症候群的主要特徵，比如說[[普瑞德威利症候群]]（俗稱小胖威利症候群）、巴德-畢德氏症候群、[[科恩綜合症|科恩症候群]]、以及MOMO症候群（有時我們會用「非症候群相關的肥胖」來排除這些疾病造成的肥胖[106]）。患有早發性嚴重肥胖的人（其定義為在十歲前就發生肥胖且身體質量指數較平均高出3個標準差以上）身上，有7%帶有一個單點[[去氧核糖核酸]]（DNA）突變。
Studies that have focused on inheritance patterns rather than on specific genes have found that 80% of the offspring of two obese parents were also obese, in contrast to less than 10% of the offspring of two parents who were of normal weight.[108] Different people exposed to the same environment have different risks of obesity due to their underlying genetics.[109]
針對特定基因的遺傳方式的研究發現雙親都肥胖的孩子有80%也會是肥胖的，而雙親都有正常體重的孩子則只有10%的機會肥胖[108]。不同的人處在同樣的環境時，也會因為他們的基因差異而有不同的肥胖風險[109]。
The thrifty gene hypothesis postulates that, due to dietary scarcity during human evolution, people are prone to obesity. Their ability to take advantage of rare periods of abundance by storing energy as fat would be advantageous during times of varying food availability, and individuals with greater adipose reserves would be more likely to survive famine. This tendency to store fat, however, would be maladaptive in societies with stable food supplies.[110] This theory has received various criticisms, and other evolutionarily-based theories such as the drifty gene hypothesis and the thrifty phenotype hypothesis have also been proposed.[111][112]
{{link-en|節儉基因假說|thrifty gene hypothesis}}主張由於在人類演化過程中面臨的飲食不足，人類變得易於肥胖。在難得的食物豐富時間將能量大量以脂肪的型式儲存的能力在食物來源不穩定的環境下是一種優勢，在饑荒時，脂肪儲存較多的人也較可能存活[110]，但在食物供應穩定的環境下，這種儲存脂肪的能力卻會變成一種適應不良[110]。節儉基因假說受到不少批評，也有許多其他基於演化的假說被提出（例如基因漂移假說與節儉表型理論）[111][112]。
其他疾病
Other illnesses
Certain physical and mental illnesses and the pharmaceutical substances used to treat them can increase risk of obesity. Medical illnesses that increase obesity risk include several rare genetic syndromes (listed above) as well as some congenital or acquired conditions: hypothyroidism, Cushing’s syndrome, growth hormone deficiency,[113] and the eating disorders: binge eating disorder and night eating syndrome.[2] However, obesity is not regarded as a psychiatric disorder, and therefore is not listed in the DSM-IVR as a psychiatric illness.[114] The risk of overweight and obesity is higher in patients with psychiatric disorders than in persons without psychiatric disorders.[115]
一些生理或心理疾病，以及藥物治療都可能增加肥胖風險。會增加肥胖風險的疾病包括前文所提的幾個症候群、以及一些先天或後天疾病：[[甲狀腺機能低下]]、[[庫欣氏症]]、[[生長激素不足]][113]、以及飲食疾患：[[暴食症]]與夜食症候群[2]。即使與部分的精神疾病相關，肥胖本身並不被認為是一種精神疾病，也未被收錄在[[精神疾病診斷與統計手冊]]第4版修訂版中[114]。整體而言，患有精神疾病者的肥胖與過重風險高於不患有精神疾病的人[115]。
Certain medications may cause weight gain or changes in body composition; these include insulin, sulfonylureas, thiazolidinediones, atypical antipsychotics, antidepressants, steroids, certain anticonvulsants (phenytoin and valproate), pizotifen, and some forms of hormonal contraception.[2]
某些藥物可能會造成身體組成改變或增重：[[胰島素]]、[[磺醯脲類]]、[[噻唑烷二酮類]]、第二代[[抗精神病藥]]、[[抗憂鬱劑]]、[[類固醇]]、部分[[抗癲癇藥]]（[[苯妥英]]與[[丙戊酸]]）、苯噻啶、以及部分的激素性[[避孕藥]][2]。
社會因子
Social determinants
While genetic influences are important to understanding obesity, they cannot explain the current dramatic increase seen within specific countries or globally.[116] Though it is accepted that energy consumption in excess of energy expenditure leads to obesity on an individual basis, the cause of the shifts in these two factors on the societal scale is much debated. There are a number of theories as to the cause but most believe it is a combination of various factors.
雖然基因對肥胖的影響很重要，但它無法解釋在部分國家甚至全球正在發生的肥胖率大幅上升現象[116]。雖然對個人來說熱量攝取高於消耗會帶來肥胖，但在社會層面上究竟是什麼造成熱量攝取與消耗的消長則仍然在爭論中，並有許多理論試圖找出原因，但多數人相信真正的原因是許多因素的總和。
The correlation between social class and BMI varies globally. A review in 1989 found that in developed countries women of a high social class were less likely to be obese. No significant differences were seen among men of different social classes. In the developing world, women, men, and children from high social classes had greater rates of obesity.[117] An update of this review carried out in 2007 found the same relationships, but they were weaker. The decrease in strength of correlation was felt to be due to the effects of globalization.[118] Among developed countries, levels of adult obesity, and percentage of teenage children who are overweight, are correlated with income inequality. A similar relationship is seen among US states: more adults, even in higher social classes, are obese in more unequal states.[119]
社會階級與身體質量指數的關聯性強弱在世界各地有所不同。1989年的評論性文章中指出在[[已開發國家]]社會地位較高的女性較不易有肥胖問題，但不同社會地位的男性的肥胖率則沒有顯著差異。在[[發展中國家]]中，社會地位較高的女性、男性、以及兒童都有較高的肥胖率[117]。該評論文章在2007年更新，發現肥胖與社會地位的關係雖然不變，但關聯性減弱。關連性的減弱被認為是全球化的影響[118]。在[[已開發國家]]中，成人肥胖率與青少年過重率都與收入不平等的關連性，這個現象在美國也能觀察到：在收入不平等的州，即使是較高社會地位的人也容易有肥胖問題[119]。
Many explanations have been put forth for associations between BMI and social class. It is thought that in developed countries, the wealthy are able to afford more nutritious food, they are under greater social pressure to remain slim, and have more opportunities along with greater expectations forphysical fitness. In undeveloped countries the ability to afford food, high energy expenditure with physical labor, and cultural values favoring a larger body size are believed to contribute to the observed patterns.[118] Attitudes toward body weight held by people in one’s life may also play a role in obesity. A correlation in BMI changes over time has been found among friends, siblings, and spouses.[120] Stress and perceived low social status appear to increase risk of obesity.[119][121][122]
對於身體質量指數與社會地位的關係有許多解釋。有些人認為在[[已開發國家]]中富人能消費營養較為均衡的食物，且維持纖細體態的社會壓力較大、且維持體適能的機會與期待都較高。在[[未開發國家]]中，負擔食物開銷的能力、高勞動帶來的高熱量消耗、以及對較胖體態的文化偏好都被認為能解釋肥胖率與社會地位的關連[118]。對於體重的態度也在肥胖的發生中佔一定角色，在朋友、兄弟姊妹、以及配偶的身上都能觀察到他們的[[身體質量指數]]的變化有關聯性[120]。壓力、低的社會地位似乎會增加肥胖率[119][121][122]。
Smoking has a significant effect on an individual’s weight. Those who quit smoking gain an average of 4.4 kilograms (9.7 lb) for men and 5.0 kilograms (11.0 lb) for women over ten years.[123] However, changing rates of smoking have had little effect on the overall rates of obesity.[124]
吸菸對個人的體重有明顯影響。男性戒菸者十年內平均會增重4.4公斤（9.7磅），女性戒菸者則會增重5公斤（11.0磅[123]），但整體而言吸菸率的變化對肥胖率並沒有明顯影響[124]。
In the United States the number of children a person has is related to their risk of obesity. A woman’s risk increases by 7% per child, while a man’s risk increases by 4% per child.[125] This could be partly explained by the fact that having dependent children decreases physical activity in Western parents.[126]
在美國，生的孩子的數量與肥胖風險是相關的。每生一個孩子，女性的肥胖風險就上升7%，而男性則會上升4%[125]。這個現象可以用在西方國家，撫養的孩子越多，家長的運動量就越少來解釋[126]。
In the developing world urbanization is playing a role in increasing rate of obesity. In China overall rates of obesity are below 5%; however, in some cities rates of obesity are greater than 20%.[127]
在[[發展中國家]]，[[都市化]]在肥胖率的上升中扮演一定的角色。在中國，平均肥胖率只有不到5%，但在某些都市肥胖率卻高達20%以上[127]。
Malnutrition in early life is believed to play a role in the rising rates of obesity in the developing world.[128] Endocrine changes that occur during periods of malnutrition may promote the storage of fat once more food energy becomes available.[128]
早年的營養不良在[[發展中國家]]的肥胖率上升也有一定的影響[128]。營養不良時期造成的內分泌變化可能會誘使身體在有食物時更容易堆積脂肪。
Consistent with cognitive epidemiological data, numerous studies confirm that obesity is associated with cognitive deficits.[129] Whether obesity causes cognitive deficits, or vice versa is unclear at present.
流行病學資料指出認知障礙與肥胖風險相關[129]，但究竟是認知障礙造成肥胖或者是反過來則尚不明朗。
感染性因素
Infectious agents
The study of the effect of infectious agents on metabolism is still in its early stages. Gut flora has been shown to differ between lean and obese humans. There is an indication that gut flora in obese and lean individuals can affect the metabolic potential. This apparent alteration of the metabolic potential is believed to confer a greater capacity to harvest energy contributing to obesity. Whether these differences are the direct cause or the result of obesity has yet to be determined unequivocally.[130]
感染性因素如何影響代謝的相關研究才剛起步。在正常體重者與肥胖者身上，我們已經知道腸道菌叢的組成是不同的，證據顯示腸道菌叢有能力影響代謝能力。在正常體重者與肥胖者身上觀察到的明顯代謝能力差異被認為暗示著從腸道中吸收熱量的能力可能對肥胖的發生有影響，但這些差異究竟會直接造成肥胖呢？或者是肥胖的結果則尚不明朗[130]。
An association between viruses and obesity has been found in humans and several different animal species. The amount that these associations may have contributed to the rising rate of obesity is yet to be determined.[131]
在人類與其他數種動物身上能觀察到病毒與肥胖的關聯，但這與肥胖率的上升是否有關則尚不明朗[131]。
Pathophysiology
There are many possible pathophysiological mechanisms involved in the development and maintenance of obesity.[132] This field of research had been almost unapproached until the leptin gene was discovered in 1994 by J. M. Friedman’s laboratory.[133] These investigators postulated that leptin was a satiety factor. In the ob/ob mouse, mutations in the leptin gene resulted in the obese phenotype opening the possibility of leptin therapy for human obesity. However, soon thereafter J. F. Caro’s laboratory could not detect any mutations in the leptin gene in humans with obesity. On the contrary Leptin expression was increased proposing the possibility of Leptin-resistance in human obesity.[134] Since this discovery, many other hormonal mechanisms have been elucidated that participate in the regulation of appetite and food intake, storage patterns of adipose tissue, and development of insulin resistance. Since leptin’s discovery, ghrelin, insulin, orexin, PYY 3-36, cholecystokinin, adiponectin, as well as many other mediators have been studied. The adipokines are mediators produced by adipose tissue; their action is thought to modify many obesity-related diseases.
肥胖的發生與維持有許多種可能的病生理機轉[132]，但這個研究領域在1994年J·M·弗萊德曼（{{lang|en|J. M. Friedman}}）的研究團隊發現[[瘦蛋白|瘦素]]基因前都乏人問津[133]。J·M·弗萊德曼的研究團隊認為[[瘦蛋白|瘦素]]是影響飽足感的因子。實驗中發現{{link-en|胖胖鼠|ob/ob mouse}}(一種意外發現具有過度食慾並且會變得極端肥胖的實驗用小鼠}}帶有突變[[瘦蛋白|瘦素]]基因，因此展現肥胖的表現型，這個結果開啟以[瘦蛋白|瘦素]來治療人類肥胖的可能性，但不久後J·F·卡羅（{{lang|en|J. F. Caro}}）的研究團隊就發現無法在肥胖的人身上找到任何瘦素基因上的突變。另一方面，在肥胖的人身上的[瘦蛋白|瘦素]基因表現量上升，反而指出了肥胖者身上可能有瘦素抵抗現象[134]。在發現瘦素後，研究者陸續發現許多其他影響食慾、進食、脂肪儲存、胰島素抗性的激素作用，舉例來說{{link-en|饑餓素|ghrelin}}、[[胰島素]]、[[食慾素]]、{{link-en|雙酪胺酸肽3-36|peptide YY}}、[[膽囊收縮素]]、[[脂聯素]]等因子都是學者研究的對象。脂激素是由脂肪組織釋放出的訊息因子，而它們的作用會影響許多肥胖相關的疾病。
Leptin and ghrelin are considered to be complementary in their influence on appetite, with ghrelin produced by the stomach modulating short-term appetitive control (i.e. to eat when the stomach is empty and to stop when the stomach is stretched). Leptin is produced by adipose tissue to signal fat storage reserves in the body, and mediates long-term appetitive controls (i.e. to eat more when fat storages are low and less when fat storages are high). Although administration of leptin may be effective in a small subset of obese individuals who are leptin deficient, most obese individuals are thought to be leptin resistant and have been found to have high levels of leptin.[135] This resistance is thought to explain in part why administration of leptin has not been shown to be effective in suppressing appetite in most obese people.[132]
[[瘦蛋白|瘦素]]與{{link-en|饑餓素|ghrelin}}被認為在對食慾的影響上扮演互補的角色。饑餓素由胃製造，並負責調節短期的食慾變化，比方說在胃排空時進食並在胃裝滿時停止；而瘦素則是由脂肪組織製造，反映人體脂肪儲藏的總量，並調節長期食慾變化，比如說在脂肪儲藏量低時增加食量，並在儲藏量高時減少食量。雖然使用瘦素對一小部分瘦素缺乏的肥胖者有效，但目前認為絕大多數的肥胖者都有瘦素抗性，在他們的身體中也都已經有高濃度的瘦素[135]。瘦素抗性能解釋為何使用瘦素無法有效減少多數肥胖者的食量[132]。
While leptin and ghrelin are produced peripherally, they control appetite through their actions on the central nervous system. In particular, they and other appetite-related hormones act on the hypothalamus, a region of the brain central to the regulation of food intake and energy expenditure. There are several circuits within the hypothalamus that contribute to its role in integrating appetite, the melanocortin pathway being the most well understood.[132] The circuit begins with an area of the hypothalamus, the arcuate nucleus, that has outputs to the lateral hypothalamus (LH) and ventromedial hypothalamus (VMH), the brain’s feeding and satiety centers, respectively.[136]
[[瘦蛋白|瘦素]]與{{link-en|饑餓素|ghrelin}}雖然由周邊組織製造和分泌，它們仍然需要影響[[中樞神經系統]]來發揮調節食慾的功能。更精確的說，它們以及其他食慾相關激素會作用在[[下視丘]]，這是腦中負責管理進食與能量消耗的中心。下視丘中有幾個迴路在調節食慾中扮演重要角色。{{link-en|黑皮質素|melanocortin}}路徑是目前我們了解最透徹的[132]，它從下視丘的[[弓狀核]]出發，前進至{link-en|下視丘外核|lateral hypothalamus}}與{link-en|下視丘腹中核|ventromedial nucleus}}，這兩個核分別是腦中的進食中樞與飽足中樞[136]。
The arcuate nucleus contains two distinct groups of neurons.[132] The first group coexpresses neuropeptide Y (NPY) and agouti-related peptide (AgRP) and has stimulatory inputs to the LH and inhibitory inputs to the VMH. The second group coexpresses pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) and has stimulatory inputs to the VMH and inhibitory inputs to the LH. Consequently, NPY/AgRP neurons stimulate feeding and inhibit satiety, while POMC/CART neurons stimulate satiety and inhibit feeding. Both groups of arcuate nucleus neurons are regulated in part by leptin. Leptin inhibits the NPY/AgRP group while stimulating the POMC/CART group. Thus a deficiency in leptin signaling, either via leptin deficiency or leptin resistance, leads to overfeeding and may account for some genetic and acquired forms of obesity.[132]
[[弓狀核]]內含有兩群[[神經元]][132]：第一群同時表現{{link-en|神經肽Y|neuropeptide Y}}與{{link-en|刺豚鼠關聯肽|agouti-related peptide}}，它們會刺激{link-en|下視丘外核|lateral hypothalamus}}並抑制{link-en|下視丘腹中核|ventromedial nucleus}}；第二群則表現pro-opiomelanocortin與[[古柯鹼]]-[[安非他命]]關聯轉錄，並會刺激{link-en|下視丘腹中核|ventromedial nucleus}}並抑制下視丘外核。因此表現神經肽Y與刺豚鼠關聯肽的神經元會促進進食並抑制飽足感；而表現{{link-en|鴉片黑皮質素原|proopiomelanocortin}}與[[古柯鹼]]-[[安非他命]]調控轉錄因子的神經元則反過來會抑制進食並激發飽足感。在[[弓狀核]]中的兩組神經元都受[瘦蛋白|瘦素]調控：[[瘦蛋白|瘦素]]會抑制表現神經肽Y與刺豚鼠關聯肽的神經元並刺激表現鴉片黑皮質素原與古柯鹼-安非他命調控轉錄因子的神經元。因此如果瘦素相關的訊息傳導不足（可能由於瘦素不足或是瘦素抵抗），就會產生過度進食的情形，也能解釋某些基因疾病與後天狀況造成的肥胖。
Public health
The World Health Organization (WHO) predicts that overweight and obesity may soon replace more traditional public health concerns such as undernutrition and infectious diseases as the most significant cause of poor health.[137] Obesity is a public health and policy problem because of its prevalence, costs, and health effects.[138] The United States Preventive Services Task Force recommends screening for all adults followed by behavioral interventions in those who are obese.[139] Public health efforts seek to understand and correct the environmental factors responsible for the increasing prevalence of obesity in the population. Solutions look at changing the factors that cause excess food energy consumption and inhibit physical activity. Efforts include federally reimbursed meal programs in schools, limiting direct junk food marketing to children,[140] and decreasing access to sugar-sweetened beverages in schools.[141] When constructing urban environments, efforts have been made to increase access to parks and to develop pedestrian routes.[142]
[[世界衛生組織]]預測過重與肥胖將在近期取代傳統造成健康狀況不佳的主因：傳染病、營養不足等，而成為健康狀況不佳的最重要原因[137]。肥胖問題在公共衛生上與公共政策上的重要性來自於它的盛行率、造成的成本、以及對健康的影響[138]。{link-en|美國預防服務工作小組|United States Preventive Services Task Force}}建議對所有成年人進行肥胖篩檢，並對肥胖者進行行為介入與追蹤[139]。公共衛生手段試圖理解並修正造成肥胖人口上升的環境因素，而提供方案以改正造成食物熱量攝取過高與運動量不足的因素。美國目前採行的方案包括聯邦出資的校園飲食計畫、限制孩童對垃圾食物的可近性[140]以及減少校園含糖飲料的可近性[141]，另外在都市設計上也增加公園的可近性並增加人行道路。
Many countries and groups have published reports pertaining to obesity. In 1998 the first US Federal guidelines were published, titled "Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report".[143] In 2006 the Canadian Obesity Network published the "Canadian Clinical Practice Guidelines (CPG) on the Management and Prevention of Obesity in Adults and Children". This is a comprehensive evidence-based guideline to address the management and prevention of overweight and obesity in adults and children.[68]
許多國家或組織發表針對肥胖問題的報告。1998年時美國發表第一篇聯邦肥胖治療指引(「成人過重與肥胖之診斷、評估與治療臨床指引：證據報告(Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report)」)[143]；於2006年加拿大肥胖網路發表「加拿大成人與兒童肥胖預防暨治療臨床指引(Canadian Clinical Practice Guidelines (CPG) on the Management and Prevention of Obesity in Adults and Children)」，這是一份完整的證據導向臨床指引，內容包括成人及兒童的過重與肥胖的治療與預防[68]。
In 2004, the United Kingdom Royal College of Physicians, the Faculty of Public Health and the Royal College of Paediatrics and Child Health released the report "Storing up Problems", which highlighted the growing problem of obesity in the UK.[144] The same year, the House of Commons Health Select Committee published its "most comprehensive inquiry [...] ever undertaken" into the impact of obesity on health and society in the UK and possible approaches to the problem.[145] In 2006, the National Institute for Health and Clinical Excellence (NICE) issued a guideline on the diagnosis and management of obesity, as well as policy implications for non-healthcare organizations such as local councils.[146] A 2007 report produced by Sir Derek Wanless for the King’s Fund warned that unless further action was taken, obesity had the capacity to cripple the National Health Service financially.[147]
英國皇家內科醫學院、公共衛生學院與皇家兒科暨兒童健康學院於2004年發表「堆積起來的問題(Storing up Problems)」強調英國日漸嚴重的肥胖問題[144]。同年英國下議院健康遴選委員會發表了它針對肥胖問題對英國健康與社會衝擊的「史上最完整的調查報告」，內文並包括了可能的解決手段[145]。英國國家健康與照顧卓越研究院在2006年發表了肥胖的診斷與治療的臨床指引，以及針對非醫療組織(比方說地方政府)的策略指引[146]。國王基金會(the King’s Fund)的Derek Wanless爵士於2007發表的報告警告若不採取對策，肥胖問題將拖垮英國[國民保健署]的財務[147]。
Comprehensive approaches are being looked at to address the rising rates of obesity. The Obesity Policy Action (OPA) framework divides measure into ’upstream’ policies, ’midstream’ policies, ’downstream’ policies. ’Upstream’ policies look at changing society, ’midstream’ policies try to alter individuals’ behavior to prevent obesity, and ’downstream’ policies try to treat currently afflicted people.[148]
完整的對策是處理肥胖問題的主流，肥胖政策與行動框架(Obesity Policy Action (OPA) framework)將對策區分為：上游、中游、與下游策略。上游策略主要試圖改變社會；中游策略則試圖改變個人行為以預防肥胖；下游策略則是治療已經肥胖的人口[148]。
6 Management
The main treatment for obesity consists of dieting and physical exercise.[68] Diet programs may produce weight loss over the short term,[149] but maintaining this weight loss is frequently difficult and often requires making exercise and a lower food energy diet a permanent part of a person’s lifestyle.[150][151] All types of low-carbohydrate and low-fat diets appear equally beneficial.[152] The heart disease and diabetes risks associated with different diets also appear to be similar.[153] Success rates of long-term weight loss maintenance with lifestyle changes are low, ranging from 2–20%.[154] Dietary and lifestyle changes are effective in limiting excessive weight gain in pregnancy and improve outcomes for both the mother and the child.[155] Intensive behavioral counseling is recommended in those who are both obese and have other risk factors for heart disease.[156]
治療肥胖的主要手段是飲食控制與運動[68]。飲食計畫能在短期達到減重效果[149]，但要維持減重的成果經常相當困難，常需要搭配運動以及永久性的選擇熱量較低的食物[150][151]。各種低[碳水化合物]與低脂飲食對健康的幫助似乎沒有差別[152]，在心臟疾病與糖尿病的風險上這些飲食策略也表現地不相上下[153]。長期的減重成功率與生活形態改變率並不高，約為2-20%[154]。飲食與生活形態改變在控制懷孕期間的體重增加與改善母嬰健康上是有效的[155]。目前建議具有肥胖外的心臟疾病風險因子的肥胖者接受密集的行為諮詢[156]。
Three medications, orlistat (Xenical), lorcaserin (Belviq) and a combination of phentermine and topiramate (Qsymia) are currently available and have evidence for long term use.[157] Weight loss with orlistat is modest, an average of 2.9 kg (6.4 lb) at 1 to 4 years.[158] Its use is associated with high rates of gastrointestinal side effects[158] and concerns have been raised about negative effects on the kidneys.[159] The other two medications are available in the United States but not Europe.[160] Lorcaserin results in an average 3.1 kg weight loss (3% of body weight) greater than placebo over a year;[161] however it may increase heart valve problems.[160] A combination of phentermine and topiramate is also somewhat effective;[162] however, it may be associated with heart problems.[160] There is no information on how these drugs affect longer-term complications of obesity such as cardiovascular disease or death.[157]
針對肥胖目前市面有三種藥物([奧利司他](羅氏鮮)、{{link-en|洛卡色林lorcaserin}}(Belviq)以及芬他命與托吡酯併用的Qsymia受證據支持長期使用[157]。[奧利司他]能少量減輕體重，平均約為在一到四年間減少2.9公斤(6.4磅)[158]，但有相當高的機會產生腸胃副作用[158]，它對腎臟的影響也受到質疑[159]。另外兩種藥物則只在美國而未在歐洲上市[160]。洛卡色林平均能在一年內比安慰劑多減少3.1公斤的體重(3%體重)[161]，但可能會引發心臟瓣膜問題[160]。芬他命與托吡酯同時使用也具有某種程度的減重效果[162]，但使用這兩種藥物同樣與心臟問題有關聯性[160]。現下還沒有資料能闡明這些減重藥物對肥胖的長期併發症(比方說心血管疾病與死亡)的影響[157]。
//我實在很不想翻出洛卡色林這種東西…
The most effective treatment for obesity is bariatric surgery.[163] Surgery for severe obesity is associated with long-term weight loss, improvement in obesity related conditions,[164] and decreased overall mortality. One study found a weight loss of between 14% and 25% (depending on the type of procedure performed) at 10 years, and a 29% reduction in all cause mortality when compared to standard weight loss measures.[165] Complications occur in about 17% of cases and reoperation is needed in 7% of cases.[164] Due to its cost and risks, researchers are searching for other effective yet less invasive treatments including devices that occupy space in the stomach.[166]
對肥胖最有效的治療是[減肥手術][163]。嚴重肥胖者接受手術後能達成長期的體重減輕、肥胖相關問題的改善[164]、以及死亡率的下降。一項研究指出手術能在十年間減輕14%-25%的體重(視手術方法而定)，並相對於一般減重方法多減低29%的死亡率[165]。手術併發症的發生率為17%，並且有7%的病人需要接受第二次手術[164]。因為手術的花費與風險，研究者們正在尋找較不侵入性卻同樣有效的治療方法，比如說在胃中置入佔空間的植入物來減少胃容量[166]。
Epidemiology
流行病學
In earlier historical periods obesity was rare, and achievable only by a small elite, although already recognised as a problem for health. But as prosperity increased in the Early Modern period, it affected increasingly larger groups of the population.[168] In 1997 the WHO formally recognized obesity as a global epidemic.[81] As of 2008 the WHO estimates that at least 500 million adults (greater than 10%) are obese, with higher rates among women than men.[169] The rate of obesity also increases with age at least up to 50 or 60 years old[170] and severe obesity in the United States, Australia, and Canada is increasing faster than the overall rate of obesity.[19][171][172]
Once considered a problem only of high-income countries, obesity rates are rising worldwide and affecting both the developed and developing world.[31]These increases have been felt most dramatically in urban settings.[169] The only remaining region of the world where obesity is not common is sub-Saharan Africa.[2]
在近代以前，肥胖雖然已經被認為會造成健康問題，但肥胖並不常見，只發生在少數的菁英階級身上。但隨著[近代史|近代]物質生活的日益富足，肥胖的影響擴及更多人[168]。1997年[世界衛生組織]將肥胖視為全球性的流行病[81]。到了2008年，[世界衛生組織]估計至少有五億的成人人口(大於10%成人人口)有肥胖問題，而女性的肥胖問題又比男性嚴重[169]。到五十至六十歲前，肥胖率都會隨著年齡上升[170]，而[美國]、[澳洲]、[加拿大]的嚴重肥胖比率上升的比整體的肥胖率還快[19][171][172]。
History
歷史
8.1 Etymology
字源
Obesity is from the Latin obesitas, which means "stout, fat, or plump". Ēsus is the past participle of edere (to eat), with ob (over) added to it.[173] The Oxford English Dictionary documents its first usage in 1611 by Randle Cotgrave.[174]
肥胖的英文(obesity)來自拉丁語的obesitas，指的是體型大、肥、或渾圓。Esus則是edere(進食)的過去分詞，並前綴了ob(過度地)修飾它[173]。據牛津大辭典記載，Randle Cotgrave在1611年首次使用肥胖這個單詞[174]。
8.2 Historical attitudes
歷史：看待肥胖的態度
Ancient Greek medicine recognizes obesity as a medical disorder, and records that the Ancient Egyptians saw it in the same way.[168] Hippocrates wrote that "Corpulence is not only a disease itself, but the harbinger of others".[2] The Indian surgeon Sushruta (6th century BCE) related obesity to diabetes and heart disorders.[176] He recommended physical work to help cure it and its side effects.[176] For most of human history mankind struggled with food scarcity.[177] Obesity has thus historically been viewed as a sign of wealth and prosperity. It was common among high officials in Europe in the Middle Ages and the Renaissance[175] as well as in Ancient East Asian civilizations.[178]
古希臘醫學將肥胖視為一種疾病，而古埃及的文獻也是如此[168]。[希波克拉底]這麼寫道：「肥胖本身不是一種病，但它是其他疾病的前兆。」公元前六世紀的印度外科醫師Sushruta認為肥胖與[糖尿病]與[心血管疾病]有關[176]，並建議以運動來治療肥胖以及與肥胖相關的狀態[176]。在大部分的歷史中，人類都在食物缺乏中掙扎[177]，因此肥胖被視為財富與繁榮的象徵。在[中世紀]與[文藝復興時代][175]的歐洲高官身上以及古代東亞文明的權貴身上都經常可以見到肥胖的情形[178]。
With the onset of the industrial revolution it was realized that the military and economic might of nations were dependent on both the body size and strength of their soldiers and workers.[81]Increasing the average body mass index from what is now considered underweight to what is now the normal range played a significant role in the development of industrialized societies.[81]Height and weight thus both increased through the 19th century in the developed world. During the 20th century, as populations reached their genetic potential for height, weight began increasing much more than height, resulting in obesity.[81] In the 1950s increasing wealth in the developed world decreased child mortality, but as body weight increased heart and kidney disease became more common.[81][179] During this time period insurance companies realized the connection between weight and life expectancy and increased premiums for the obese.[2]
隨著[工業革命]的發生，人們開始認為國家的軍事經濟力量立基於軍人與工人的體態與力量[81]，因此平均[身體質量指數]從今日視為體重過輕的程度提升至正常範圍的事實，在[工業化]社會的建立過程中扮演了重要的角色[81]。從十九世紀開始，在[已開發國家]中平均身高與體重都開始上升。到了二十世紀，身高已經達到基因潛力的上限，於是體重的成長就超過身高而開始產生肥胖[81]。一九五○年代，[已開發國家]的兒童死亡率因財富的累積而下降，但心臟疾病與腎臟疾病發生率則隨著體重的上升而爬升[81][179]。在此同時，保險業發覺體重與預期壽命間的關聯性，並調漲肥胖者的保費[2]。
Many cultures throughout history have viewed obesity as the result of a character flaw. The obesus or fat character in Greek comedy was a glutton and figure of mockery. During Christian times food was viewed as a gateway to the sins of sloth and lust.[9] In modern Western culture, excess weight is often regarded as unattractive, and obesity is commonly associated with various negative stereotypes. People of all ages can face social stigmatization, and may be targeted by bullies or shunned by their peers. Obesity is once again a reason for discrimination.[180]
歷史上，許多文化都認為肥胖是人格上瑕疵的結果。在希臘喜劇中，肥胖的角色通常是貪吃的人，也是被嘲弄的對象。在[基督教]信仰中，食物被認為會令人犯下[暴食]與[貪婪]兩項原罪[9]。在當代西方文化中，肥胖經常被視為不受歡迎的同義詞，也與許多負面刻板印象相關。不論年齡，肥胖的人都可能面對社交上的汙名化，並可能遭受[霸凌]或被同儕排擠，肥胖於是成為歧視的原因[180]。
Public perceptions in Western society regarding healthy body weight differ from those regarding the weight that is considered ideal – and both have changed since the beginning of the 20th century. The weight that is viewed as an ideal has become lower since the 1920s. This is illustrated by the fact that the average height of Miss America pageant winners increased by 2% from 1922 to 1999, while their average weight decreased by 12%.[181] On the other hand, people’s views concerning healthy weight have changed in the opposite direction. In Britain the weight at which people considered themselves to be overweight was significantly higher in 2007 than in 1999.[182] These changes are believed to be due to increasing rates of adiposity leading to increased acceptance of extra body fat as being normal.[182]
Obesity is still seen as a sign of wealth and well-being in many parts of Africa. This has become particularly common since the HIV epidemic began.[2]
西方社會並不認為「健康體重」與「理想體重」是同一件事，而且對這兩件事的認識在二十世紀中開始發生變化。「理想體重」的標準自一九二○年代開始下降：自1922年至1999年間，美國小姐的身高上升了2%，但體重卻下降了12%[181]；但在此同時人們對「健康體重」的標準則反其道而行：2007年的英國人對於過重的標準，相對於1999年時來得寬鬆得多[182]。這些變化被認為是因為人們的體脂不斷上升，因此人們開始認為過剩的體脂是一種正常的表現[182]。在[非洲]的許多地區，肥胖仍然被視為富裕與健康的表現，尤其在[人類免疫缺陷病毒]疫情發生後，這樣的看法變得越來越常見[2]。
8.3 The arts
藝術
The first sculptural representations of the human body 20,000–35,000 years ago depict obese females. Some attribute the Venus figurines to the tendency to emphasize fertility while others feel they represent "fatness" in the people of the time.[9] Corpulence is, however, absent in both Greek and Roman art, probably in keeping with their ideals regarding moderation. This continued through much of Christian European history, with only those of low socioeconomic status being depicted as obese.[9]
最早的人體雕塑創作於二萬到三萬五千年前，主要描繪肥胖的女體。有些人認為[維納斯]塑像的表現方式象徵的是多產，但也有些人認為單純是在表現生活在創作年代的人們的肥胖程度[9]。在希臘與羅馬的藝術創作中，幾乎見不到肥胖的人物，這或許與他們文化中對於適中的追求有關，而希臘羅馬傳統也被多數的基督信仰歐洲文化所繼承：在他們的創作中，只有低社經地位的角色才會是肥胖的[9]。
During the Renaissance some of the upper class began flaunting their large size, as can be seen in portraits of Henry VIII of England and Alessandro del Borro.[9] Rubens (1577–1640) regularly depicted full-bodied women in his pictures, from which derives the term Rubenesque. These women, however, still maintained the "hourglass" shape with its relationship to fertility.[183] During the 19th century, views on obesity changed in the Western world. After centuries of obesity being synonymous with wealth and social status, slimness began to be seen as the desirable standard.[9]
自[文藝復興時代]開始，部分上層階級開始炫耀自己的心寬體胖，我們可以在英王[亨利八世]與{{link-en|亞歷山卓·達·布羅|Alessandro dal Borro}}的畫像中看到這樣的趨勢[9]。知名畫家[[彼得·保羅·魯本斯|魯本斯]]經常描繪{{link-en|魯本斯式|Rubenesque}}的女性全身像，雖然表現上也強調多產，但在他畫中的女性仍然維持沙漏狀的身形[183]。到了十九世紀，整個西方世界對於肥胖的看法開始改變，在肥胖做為財富與地位的象徵許多世紀以後，纖瘦取而代之成為新的追求目標。
9 Society and culture
9.1 Economic impact
經濟衝擊
In addition to its health impacts, obesity leads to many problems including disadvantages in employment[184][185] and increased business costs. These effects are felt by all levels of society from individuals, to corporations, to governments.
In 2005, the medical costs attributable to obesity in the US were an estimated $190.2 billion or 20.6% of all medical expenditures,[186][187][188] while the cost of obesity in Canada was estimated at CA$2 billion in 1997 (2.4% of total health costs).[68] The total annual direct cost of overweight and obesity in Australia in 2005 was A$21 billion. Overweight and obese Australians also received A$35.6 billion in government subsidies.[189] The estimate range for annual expenditures on diet products is $40 billion to $100 billion in the US alone.[190]
Obesity prevention programs have been found to reduce the cost of treating obesity-related disease. However, the longer people live, the more medical costs they incur. Researchers therefore conclude that reducing obesity may improve the public’s health, but it is unlikely to reduce overall health spending.[191]
肥胖不僅對健康產生影響，也帶來許多其他面向的問題，比方說就業困難與經營成本上升等[184][185]。肥胖的影響廣及社會中的各個層面，下至個人、公司行號，上達政府。2005年美國醫療支出中有20.6%與肥胖相關，估計為1902億美元[186][187][188]；在1997年的加拿大，肥胖則佔據2.4%的醫療支出，達到二十億加幣[68]；在2005年的澳洲，這個數字則是二百一十億澳幣，過重與肥胖的澳洲人並從政府領取三百五十六億澳幣的各式補助[189]。在美國，每年花在食物上的開銷估計則有四百到一千億美元[190]。
Obesity can lead to social stigmatization and disadvantages in employment.[184] When compared to their normal weight counterparts, obese workers on average have higher rates of absenteeism from work and take more disability leave, thus increasing costs for employers and decreasing productivity.[193] A study examining Duke University employees found that people with a BMI over 40 kg/m2 filed twice as many workers’ compensation claims as those whose BMI was 18.5–24.9 kg/m2. They also had more than 12 times as many lost work days. The most common injuries in this group were due to falls and lifting, thus affecting the lower extremities, wrists or hands, and backs.[194] The Alabama State Employees’ Insurance Board approved a controversial plan to charge obese workers $25 a month for health insurance that would otherwise be free unless they take steps to lose weight and improve their health. These measures started in January 2010 and apply to those state workers whose BMI exceeds 35 kg/m2 and who fail to make improvements in their health after one year.[195]
肥胖可能帶來社交上的汙名化與就業困難[184]。比起一般體重的人，肥胖的求職者較常缺席與請病假，因此對於雇主來說會造成人事成本的上升與生產力的下降[193]。對於杜克大學雇員進行的研究顯示，[[身體質量指數]]超過40公斤/平方公尺的雇員申請{{link-en|勞工災害補償保險|Workers compensation}}的頻率是常人（身體質量指數介於18.5至24.9公斤/平方公尺）的兩倍，無法工作的日數則比常人多了十二倍。在身體質量指數大於40公斤/平方公尺的人身上最常見到的傷害發生在下肢、手腕、手部、背部，通常源自跌倒與攀爬[194]。阿拉巴馬州雇員保險委員會通過一項爭議性的方案，方案中規定過重的雇員若不接受減重方案以改善健康，每月就需多付25美元的健康保險費，這個方案在2010年一月開始施行，主要針對身體質量指數超過35公斤/平方公尺且在一年後仍無法改善自身健康狀況的雇員[195]。
Some research shows that obese people are less likely to be hired for a job and are less likely to be promoted.[180] Obese people are also paid less than their non-obese counterparts for an equivalent job; obese women on average make 6% less and obese men make 3% less.[196]
Specific industries, such as the airline, healthcare and food industries, have special concerns. Due to rising rates of obesity, airlines face higher fuel costs and pressures to increase seating width.[197] In 2000, the extra weight of obese passengers cost airlines US$275 million.[198] The healthcare industry has had to invest in special facilities for handling severely obese patients, including special lifting equipment and bariatric ambulances.[199] Costs for restaurants are increased by litigation accusing them of causing obesity.[200] In 2005 the US Congress discussed legislation to prevent civil lawsuits against the food industry in relation to obesity; however, it did not become law.[200]
部分研究顯示肥胖的人在就職與升遷都比常人困難[180]，即使在同樣工作內容的職位上，肥胖的人的薪資也相對較低（肥胖的女性的薪資較平均低6%；肥胖的男性則低3%）[196]。肥胖對部分行業（包括航空、醫療、以及飲食）會產生額外的影響。舉例而言，因應肥胖率的上升，航空公司必須付出更高的燃料費，並面臨加大座位的壓力[197]，在2000年肥胖的旅客讓航空公司多花了2.75億美元[198]。醫療業必須為了肥胖的患者準備特別的設備，比方說升降梯或者是{{link-en|大型救護車|bariatric ambulance}}[199]。餐飲業則面臨指控他們提供的飲食造成肥胖的訴訟，進而將訴訟成本轉嫁到價格上[200]。2005年美國國會研議立法禁止人民向餐飲業因「造成肥胖」提出訴訟，但並沒有通過[200]。
With the American Medical Association’s 2013 classification of obesity as a chronic disease,[10] it is thought that health insurance companies will more likely pay for obesity treatment, counseling and surgery, and the cost of research and development of fat treatment pills or gene therapy treatments should be more affordable if insurers help to subsidize their cost.[201] The AMA classification is not legally binding, however, so health insurers still have the right to reject coverage for a treatment or procedure.[201]
In 2014, The European Court of Justice ruled that morbid obesity is a disability. The Court argued that if an employee’s obesity prevents him from "full and effective participation of that person in professional life on an equal basis with other workers", then it shall be considered a disability and that firing someone on such grounds is discriminatory.[202]
[[美國醫學會]]在2013年將肥胖列入慢性病[10]，希望藉此鼓勵健康保險業者將更多針對肥胖的治療、諮詢、及手術列入給付，如果保險業者願意投資，針對減肥藥物的發展或基因療法的成本門檻也會降低[201]。但由於美國醫學會的分類方式並沒有法律上的強制力，保險業者仍然有拒絕給付針對肥胖的治療與處置的權利[201]。2014年，[[歐洲法院]]認定病態肥胖為殘障，它指出若雇員的肥胖狀況使其無法「以與其他雇員平等的立足點，有效且全職的參與工作」，這樣的肥胖就應該被視為殘障，而因為肥胖而解雇員工也將被視為歧視行為[202]。
9.2 Size acceptance
體型與認同
The principal goal of the fat acceptance movement is to decrease discrimination against people who are overweight and obese.[203][204] However, some in the movement are also attempting to challenge the established relationship between obesity and negative health outcomes.[205]
A number of organizations exist that promote the acceptance of obesity. They have increased in prominence in the latter half of the 20th century.[206] The US-based National Association to Advance Fat Acceptance (NAAFA) was formed in 1969 and describes itself as a civil rights organization dedicated to ending size discrimination.[207]
肥胖認同運動主要的目的是減少針對過重與肥胖者的歧視[203][204]，部分的倡議者同時也試著挑戰肥胖與健康狀況惡化間的關聯性[205]。主張認同肥胖的團體在二十世紀後半開始增加，{{link-en|國家肥胖認同推廣協會|National Association to Advance Fat Acceptance}}成立於1969年，主要的活動範圍在美國，並定位為倡議消除體型歧視的人權團體[207]。
The International Size Acceptance Association (ISAA) is a non-governmental organization (NGO) which was founded in 1997. It has more of a global orientation and describes its mission as promoting size acceptance and helping to end weight-based discrimination.[208] These groups often argue for the recognition of obesity as a disability under the US Americans With Disabilities Act (ADA). The American legal system, however, has decided that the potential public health costs exceed the benefits of extending this anti-discrimination law to cover obesity.[205]
{{link-en|國際體型認同協會|International Size Acceptance Association}}是創立於1997年的[[非政府組織]]，它的宗旨是推動體型認同並消除體重歧視[208]，活動範圍廣及全球。這些倡議團體主張肥胖應列入{{link-en|美國殘障者法案|Americans With Disabilities Act}}，但立法當局則認為肥胖帶來的公共衛生成本超過將肥胖列入這部反歧視法案帶來的好處[205]。
//NAAFA/ISAA/ADA
10 Childhood obesity
The healthy BMI range varies with the age and sex of the child. Obesity in children and adolescents is defined as a BMI greater than the 95th percentile.[15] The reference data that these percentiles are based on is from 1963 to 1994 and thus has not been affected by the recent increases in rates of obesity.[16] Childhood obesity has reached epidemic proportions in the 21st century, with rising rates in both the developed and developing world. Rates of obesity in Canadian boys have increased from 11% in the 1980s to over 30% in the 1990s, while during this same time period rates increased from 4 to 14% in Brazilian children.[209]
As with obesity in adults, many factors contribute to the rising rates of childhood obesity. Changing diet and decreasing physical activity are believed to be the two most important causes for the recent increase in the incidence of child obesity.[210] Because childhood obesity often persists into adulthood and is associated with numerous chronic illnesses, children who are obese are often tested for hypertension, diabetes, hyperlipidemia, and fatty liver.[68] Treatments used in children are primarily lifestyle interventions and behavioral techniques, although efforts to increase activity in children have had little success.[211] In the United States, medications are not FDA approved for use in this age group.[209]
對兒童來說健康的身體質量指數範圍因年齡和性別而有所不同。兒童與青少年的肥胖標準是身體質量指數超過95百分位[15]，決定百分位的參考常模來自於1963年至1994年間的研究資料，因此並未計入近年來肥胖率的上升[16]。兒童的肥胖在二十一世紀已經成為一種流行病，不論是在[[發展中國家]]或是[[已開發國家]]，兒童肥胖率都不斷上升。在加拿大，兒童肥胖率自1980年代的11%爬升到1990年代的30%，在此同期，巴西的兒童肥胖率則自4%上升到14%[209]。如同成人的肥胖，兒童肥胖也受許多不同的因素影響。飲食習慣的改變與運動量的下降被認為是近年來兒童肥胖率上升的主要推手[210]。由於兒童肥胖常持續到成人，並與許多慢性病息息相關，我們經常需要篩檢肥胖兒童是否患有[[高血壓]]、[[糖尿病]]、{{link-en|高血脂|hyperlipidemia}}、以及[[脂肪肝]][68]。對於兒童肥胖的治療主要是生活型態的改變以及行為治療，但增加兒童運動量的嘗試效果並不明顯[211]。在美國，目前食品藥物管理署並未核准任何藥物用於兒童肥胖[209]。
11 Other animals
Obesity in pets is common in many countries. In the United States, 23–41% of dogs are overweight, and about 5.1% are obese.[212] The rate of obesity in cats was slightly higher at 6.4%.[212] In Australia the rate of obesity among dogs in a veterinary setting has been found to be 7.6%.[213] The risk of obesity in dogs is related to whether or not their owners are obese; however, there is no similar correlation between cats and their owners.[214]
在許多國家，寵物肥胖是常見的問題。在美國，有23到41%的狗過重，當中有5.1%達到肥胖的程度[212]；貓的肥胖率則稍高一些（6.4%）[212]。在澳洲，獸醫統計的犬隻肥胖率為7.6%[213]。犬隻肥胖的風險與飼主是否肥胖相關，但貓隻的風險則與飼主肥胖與否無關[214]。
2015-04-19 尚未整合此篇至中文維基百科「肥胖症 」條目，可先整合至草稿區 中
2015-11-19開始整合此篇至中文維基百科「肥胖症 」條目