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1. A body mass index of >30 kg/m2, an unhealthy accumulation of body fat. In adults, damaging effects of excess weight are seen when the body mass index exceeds 25 kg/m2. A person 5′7″ tall and weighing more than 191 lb would be obese by this standard.
SYN: SEE: adiposis; SEE: adiposity; SEE: corpulence; SEE: liposis; SEE: weight
SEE: body mass index for table
Obesity is the most common metabolic/nutritional disease in the U.S., with more than 65% of the adult population being overweight. Obesity is more common in women, minorities, and the poor. The obese have an increased risk of developing diabetes mellitus, hypertension, heart disease, stroke, fatal cancers, and other illnesses. Obese people may also suffer psychologically and socially.
Obesity is the end result of an imbalance between food eaten and energy expended, but the underlying causes are more complex. Genetic, hormonal, and neurological influences all contribute to weight gain and loss. In addition, some medications (such as tricyclic antidepressants, insulin, and sulfonylurea agents) may cause patients to gain weight.
Attempts to lose weight are often unsuccessful, but mild caloric restriction, an increase in physical activity, and supportive therapies all have a role. Medications to enhance weight loss can sometimes produce weight losses of several kilograms. However, some weight loss agents (such as amphetamines or amphetamine-like agents) have unacceptable side effects (such as cardiac valvular injuries with fenfluramine/phentermine, addiction with other anorexiants). Surgical remedies (bariatric surgery) are available for some patients and can result in sustained weight loss, but such surgery involves significant morbidity and a 1% to 2% risk of death in the perioperative period.
Caloric intake should be less than maintenance requirements, but all essential nutrients must be included in any weight-loss regimen. Severe caloric restriction is unhealthy and should be avoided unless undertaken under strict supervision. For many patients of average size and activity, consumption of 1200 to 1600 calories a day will result in gradual loss of weight. Most fad diets provide temporary results at best.
Dietary changes should be accompanied by a complementary program of regular exercise. Exercise improves adherence to weight loss diets and consumes stored fat. For many people 35 minutes of low-level exercise performed daily (either in one long workout session or in several shorter intermittent sessions) will aid weight loss and improve other cardiovascular risk factors. Exercise programs may be hazardous for some patients; professional supervision may be recommended for some people who start an exercise program, e.g., people with a history of heart or lung disease, arthritis, or diabetes mellitus.
The U.S. Preventive Services Task Force and other promoters of public health recommend that clinicians screen all adults for obesity and offer incentive behavioral counseling to obese adults. Patients who are overweight should be screened for conditions worsened by obesity, e.g., hypertension, diabetes mellitus, and hyperlipidemia. Health care professionals can aid patients in making permanent life-style changes by discussing diet and exercise, being familiar with various eating plans, and by providing patients with a list of local weight loss centers. The patient's feelings about weight and body image should be explored to understand the individual's motivations. People who diet and exercise for health reasons tend to be the most successful. Family support is also important.
2. A condition in which an individual accumulates abnormal or excessive fat for age and gender that exceeds overweight.
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