Obesity

Obesity is a condition where the natural energy reserve, stored in the fatty tissue of humans and mammals is increased to the point where it may impair health. Obesity in wild animals is relatively rare, but it is common in domestic animals like pigs and household pets who may be overfed and underexercised. In humans it is generally considered to be a leading cause of health problems.

Excessive body weight has been shown to predispose to various forms of disease, particularly cardiovascular disease. Interventions, such as weight loss and medication, are frequently recommended to reduce the risk of developing disease. Additionally, many people undertake weight loss regimens for health and aesthetic reasons.

• BMI - Body Mass Index
• Mesotherapy

Definition

Obesity is a concept that is being continually redefined. In humans, the most common statistical estimate of obesity is the body mass index (BMI), calculated by dividing the weight by the height squared; its unit is therefore kg/m2, although no actual surface is implied. The BMI was created in the 19th century by the Belgian statistician Adolphe Quetelet.

Interpretation of the BMI:
A person with a BMI over 25.0 kg/m2 is considered overweight.
A BMI over 30.0 kg/m2 denotes obesity.
A further threshold at 35.0 kg/m2 is identified as urgent morbidity risk (morbid obesity).

The American Institute for Cancer Research considers a BMI between 18.5 and 25 to be an ideal target for a healthy individual (although several sources consider a person with a BMI of less than 20 to be underweight).

The cut-off points between categories are occasionally redefined, and may indeed differ from country to country. In June 1998 the National Institutes of Health brought official U.S. category definitions into line with those used by the WHO, moving the American "overweight" threshold from BMI 27 to BMI 25. About 30,000,000 Americans moved from "ideal" weight to being 1–10 pounds (0.5–5 kg) "overweight". In 2000, WHO was advised to consider lowering the BMI threshold for overweight in Asians from BMI 25 to BMI 23, and for obesity in Asians from BMI 30 to BMI 25, due to epidemiological studies indicating that Asians suffer a greater number of obesity-related conditions at lower BMI; however, to date, WHO has not made any changes in recommendations. In addition, some clinicians suggest raising the BMI thresholds for those of African, African-American, and Polynesian descent because members of these groups have a greater ratio of lean body mass to fat at all body weights; the proposed thresholds for these groups are BMI 26 for overweight, and BMI 32 for obesity. To date, no major professional or medical organization has officially adopted this suggestion. In the future, a healthy BMI for a given individual may be defined to some extent by his ethnic or racial origin.

As a result of this somewhat arbitrary process, the BMI cannot offer a complete diagnosis, in that it ignores fat distribution within the body (see central obesity), and the relative fat-muscle-bone contributions to total body weight. A powerful athlete may be classified as obese by the BMI due to heavy musculature, while a false-normal may be diagnosed in the case of an elderly person with very low lean mass, which masks excess adiposity. On its own, a BMI score is therefore inadequate as a diagnostic tool.

In practice, in most examples of overweightness that may be harmful to health, both doctor and patient can see "by eye" that fat is an issue. In these cases, BMI thresholds provide simple targets all patients can understand. Doctors may also use a simple measure of waist circumference (which is a better predictor of complications such insulin resistance due to visceral fat); the skinfold test, in which a pinch of skin is precisely measured to determine the thickness of the subcutaneous fat layer; or bioelectrical impedance analysis, usually only carried out at specialist clinics.

Such clinical data is rarely available in the statistical raw materials required for large public health studies, however — whereas height and weight is commonly recorded. For this essential reason, BMI remains the most commonly-used approach for public health studies, and the most useful for cross-border, longitudinal, and other types of comparative analysis.

Causative factors

Obesity is believed to be caused by excessive caloric intake accompanied with insufficient caloric expenditure. Factors that may contribute to this imbalance include:

• Limited exercise and sedentary lifestyle
• Genetic predisposition
• A high glycemic diet (i.e. a diet that consists of meals that give high postprandial blood sugar)
• Weight cycling, caused by repeated attempts to lose weight by dieting
• Underlying illness (e.g. hypothyroidism)
• An eating disorder (such as binge eating disorder)
• Stressful mentality
• Insufficient sleeping
• Smoking cessation

As with many medical conditions, obesity often develops from a combination of genetic and environmental factors. Polymorphisms in various genes controlling appetite, rate of metabolism, and adipokine release predispose to obesity, but the condition, to some extent, requires availability of sufficient calories and/or limited exercise, and possibly other factors, to develop fully. Various genetic abnormalities that predispose to obesity have been identified (such as Prader-Willi syndrome and leptin receptor mutations), but these are absent in most people with obesity. It is presumed that a large proportion of the causative genes are still to be identified.
Some eating disorders can lead to obesity, especially binge eating disorder (BED). As the name indicates, patients with this disorder are prone to overeat, often in binges. A proposed mechanism is that the eating serves to reduce anxiety, and some parallels with substance abuse can be drawn. An important additional factor is that BED patients often lack the ability to recognize hunger and satisfaction, something that is normally learned in childhood. Learning theory suggests that early childhood conceptions may lead to an association between food and a calm mental state.

Also:
American Society for Bariatric Surgery.
Founded in 1983, foremost American surgeons have formed the society's leadership and have established an excellent organization with educational and support programs for surgeons and allied health professionals. The purpose of the society is to advance the art and science of bariatric srgery.

See also:
• Obesity
• Complications of Obesity
Fat acceptance movement
Fat admirer
Feederism
Chubby culture
MOMO syndrome
Pickwickian syndrome
Healthy eating
Dieting
• Sleep Apnea

• Plastic Surgery
• Abdominoplasty
• Liposuction

• For financing of health procedures.
• For patient loans.

• This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Obesity".