Obesity
This term derives from the Latin (obesus, meaning "to eat up"), and it came
into use in English in the early 1600s to mean a condition characterized by excessive bodily fat. Excess body weight is associated with the increased storage of energy in the form of adipose tissue. Standard criteria for obesity are (1)
greater than 20 percent above ideal body weight (IDW) for a given height, as determined from actuarial tables, or (2) body mass index (BMI), defined as weight in kilograms divided by height in meters squared (kg ÷ m2 = BMI), greater than 27 for men and greater than 25 for women.
Being overweight to a statistically significant above-
average degree or having proportionately more body fat than average is believed to be due primarily to genetic factors that influence appetite, metabolism, and activity levels. Most notably, obesity is more prevalent (ten times more likely) in persons whose parents, brothers, or sisters are obese. Studies in identical twins have clearly demonstrated that genetics plays a major role. For example, nonidentical twins raised together were less similar in weight than identical twins raised apart.
Beyond the genetic component, researchers have been examining the role of hormones, most specifically leptin, a hormone secreted by fat tissue that affects the brain's appetite control centers. Leptin research continues since solid findings could help in the treatment and prevention of obesity and diseases and health problems linked to obesity, such as hypertension, stroke, and type 2 diabetes (diabetes mellitus).
The prevalence of obesity varies remarkably across ethnic groups and cultures, and across age groups. Some researchers and clinicians see similarities among certain patterns of overeating and other excessive behaviors such as drinking too much ALCOHOL, compulsive GAMBLING, engaging in "too much" sexual activity, and even exercising compulsively. Although there may be such similarities, the semantics attached to problems of overeating and OBESITY are formidable.
Not all persons whose weight is above average are obese ; not all who are obese eat excessively; not all who eat excessively become obese; and some individuals who have clinically recognized disorders centered on eating and body weight, such as BULIMIA, may or may not be obese.