Editing Obesity (section)

==Classification==
{{Main|Classification of obesity}}
{| class="wikitable" style="float: right; margin-left: 1em; text-align:center"
! Category<ref>{{cite book |url=https://apps.who.int/iris/bitstream/handle/10665/43190/9241593024_eng.pdf |title=The SuRF Report 2 |series=The Surveillance of Risk Factors Report Series (SuRF) |page=22 |publisher=World Health Organization |date=2005}}</ref>
! BMI (kg/m<sup>2</sup>)
|-
| style="text-align: left;" | Underweight
| < 18.5
|-
| style="text-align: left;" | Ideal weight
| {{Nowrap|18.5 – 24.9}}
|-
| style="text-align: left;" | Overweight
| 25.0 – 29.9
|-
| style="text-align: left;" | Obese (class I)
| 30.0 – 34.9
|-
| style="text-align: left;" | Obese (class II)
| 35.0 – 39.9
|-
| style="text-align: left;" | Obese (class III)
| ≥ 40.0
|}
[[File:Obesity6.JPG|thumb|upright=1.2|alt=A front and side view of a "Class III male living with obesity" torso. Stretch marks of the skin are visible along with gynecomastia.|A "class III male living with obesity" with a BMI of 53&nbsp;kg/m<sup>2</sup>: weight {{cvt|182|kg}}, height {{cvt|185|cm|ftin}}. He presents with [[stretch marks]] and [[Adipomastia|enlarged breasts]].]]
Obesity is typically defined as a substantial accumulation of [[body fat]] that could impact health.<ref name=WHOsheet/> Medical organizations tend to classify people living with obesity as based on [[body mass index]] (BMI) – a ratio of a person's weight in [[kilogram]]s to the [[Square (algebra)|square]] of their height in [[meter]]s. For adults, the [[World Health Organization]] (WHO) defines "[[overweight]]" as a BMI 25 or higher, and "obesity" as a BMI 30 or higher.<ref name=WHOsheet>{{cite web|title=Obesity and overweight |publisher=World Health Organization |date=9 June 2021 |url=https://www.who.int/news-room/fact-sheets/detail/obesity-and-overweight |accessdate=16 March 2022}}</ref> The U.S. [[Centers for Disease Control and Prevention]] (CDC) further subdivides obesity based on BMI, with a BMI 30 to 35 called class 1 obesity; 35 to 40, class 2 obesity; and 40+, class 3 obesity.<ref>{{cite web|title=Defining Adult Overweight and Obesity |date=7 June 2021 |publisher=U.S. Centers for Disease Control and Prevention |url=https://www.cdc.gov/obesity/adult/defining.html |accessdate=16 March 2022}}</ref>

For children, obesity measures take age into consideration along with height and weight. For children aged 5–19, the WHO defines obesity as a BMI two [[standard deviation]]s above the [[median]] for their age (a BMI around 18 for a five-year old; around 30 for a 19-year old).<ref name=WHOsheet/><ref>{{cite web|url=https://www.who.int/toolkits/growth-reference-data-for-5to19-years/indicators/bmi-for-age |accessdate=16 March 2022 |title=BMI-for-age (5–19 years) |publisher=World Health Organization}}</ref> For children under five, the WHO defines obesity as a weight three standard deviations above the median for their height.<ref name=WHOsheet/>

Some modifications to the WHO definitions have been made by particular organizations.<ref name=Bei2002/><!-- We describe the organizations that have made modification in the next few sentences --> The surgical literature breaks down class II and III or only class III obesity into further categories whose exact values are still disputed.<ref name=morbid2007>{{cite journal | vauthors = Sturm R | title = Increases in morbid obesity in the USA: 2000–2005 | journal = Public Health | volume = 121 | issue = 7 | pages = 492–6 | date = July 2007 | pmid = 17399752 | pmc = 2864630 | doi = 10.1016/j.puhe.2007.01.006 }}</ref>
* Any BMI ≥ 35 or 40&nbsp;kg/m<sup>2</sup> is ''severe obesity''.
* A BMI of ≥ 35&nbsp;kg/m<sup>2</sup> and experiencing obesity-related health conditions or ≥ 40 or 45&nbsp;kg/m<sup>2</sup> is ''morbid obesity''.
* A BMI of ≥ 45 or 50&nbsp;kg/m<sup>2</sup> is ''super obesity''.

As Asian populations develop negative health consequences at a lower BMI than [[White people|Caucasians]], some nations have redefined obesity; Japan has defined obesity as any BMI greater than 25&nbsp;kg/m<sup>2</sup><ref name=Kan2005/> while China uses a BMI of greater than 28&nbsp;kg/m<sup>2</sup>.<ref name=Bei2002>{{cite journal | vauthors = Bei-Fan Z | title = Predictive values of body mass index and waist circumference for risk factors of certain related diseases in Chinese adults: study on optimal cut-off points of body mass index and waist circumference in Chinese adults | journal = Asia Pac J Clin Nutr | volume = 11 | issue = Suppl 8 | pages = S685–93 | date = December 2002 | doi = 10.1046/j.1440-6047.11.s8.9.x }}; Originally printed as {{cite journal | vauthors = Zhou BF | title = Predictive values of body mass index and waist circumference for risk factors of certain related diseases in Chinese adults--study on optimal cut-off points of body mass index and waist circumference in Chinese adults | journal = Biomedical and Environmental Sciences | volume = 15 | issue = 1 | pages = 83–96 | date = March 2002 | pmid = 12046553 }}</ref>

The preferred obesity metric in scholarly circles is the [[body fat percentage]] (BF%) – the ratio of the total weight of person's fat to his or her body weight, and BMI is viewed merely as a way to approximate BF%.<ref>{{cite journal|url=http://bmb.oxfordjournals.org/content/53/2/238.full.pdf|title=Assessing obesity: classification and epidemiology| vauthors = Seidell JC, Flegal KM |journal=British Medical Bulletin|year=1997|volume=53 |issue=2 |pages=238–252 |doi=10.1093/oxfordjournals.bmb.a011611 |pmid=9246834 }}</ref> According to ''American Society of Bariatric Physicians'', levels in excess of 32% for women and 25% for men are generally considered to indicate obesity.<ref>{{Cite journal |last1=Lin |first1=Ting-Yun |last2=Lim |first2=Paik-Seong |last3=Hung |first3=Szu-Chun |date=2017-12-23 |title=Impact of Misclassification of Obesity by Body Mass Index on Mortality in Patients With CKD |journal=Kidney International Reports |volume=3 |issue=2 |pages=447–455 |doi=10.1016/j.ekir.2017.12.009 |issn=2468-0249 |pmc=5932305 |pmid=29725649}}</ref>

BMI is now viewed as outdated in numerous countries. It ignores variations between individuals in amounts of lean body mass, particularly [[muscle]] mass. Individuals involved in heavy physical labor or sports may have high BMI values despite having little fat. For example, more than half of all [[NFL]] players are classified as "obese" (BMI ≥ 30), and 1 in 4 are classified as "extremely obese" (BMI ≥ 35), according to the BMI metric.<ref>{{Cite web|url=http://www.webmd.com/fitness-exercise/news/20050301/many-nfl-players-fatter-than-couch-potatoes|title=Regular Exercise: How It Can Boost Your Health}}</ref> However, their mean [[body fat percentage]], 14%, is well within what is considered a healthy range.<ref>{{cite web|url=http://health.usnews.com/health-news/family-health/heart/articles/2009/05/26/nfl-players-not-at-increased-heart-risk|title=NFL Players Not at Increased Heart Risk: Study finds they showed no more signs of cardiovascular trouble than general male population}}</ref> Similarly, [[Sumo]] wrestlers are typically categorized by BMI as "severely obese" or "very severely obese"; but one study of college-aged Sumo wrestlers found that 40% of them were no longer categorized as obese when body fat percentage (with a cutoff of <25%) was used instead of BMI; this was attributed to their very high lean body mass.<ref name="Body composition and resting metabo">{{cite journal | vauthors = Yamauchi T, Abe T, Midorikawa T, Kondo M |title=Body composition and resting metabolic rate of Japanese college Sumo wrestlers and non-athlete students: are Sumo wrestlers obese? |journal=Anthropological Science |date=2004 |volume=112 |issue=2|pages=179–185 |doi=10.1537/ase.040210 |doi-access=free }}</ref>

Canada utilises BMI sparingly within their method of defining levels of obesity through use of the Edmonton Scale (for adult obesity). This scale also introduces factors such as Quality of Life, Mental Health & Mobility amongst others. In recent years, Canada chose to allow both Chile & Ireland to adapt their obesity guidelines to suit both countries' health systems. In Ireland, obesity is now defined as "a Complex, Chronic & Relapsing Disease".