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Obesity Trends

Obesity and Disability: a woman pinching her belly fat

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Severe Obesity Rates Are Increasing Fastest

SOURCE: Sturm, R., J. Ringel, and T. Andreyeva, "Increasing Obesity Rates and Disability Trends," Health Affairs, Vol. 23, No. 2, March/April 2004, pp. 1–7.

Obesity is weight that endangers health because of its high body fat relative to lean body mass. A good screener for obesity is the Body Mass Index (BMI)--a person's weight in kilograms, divided by height in meters squared.

The table (below) illustrates how the BMI is used. For example, a man or woman who is 5'6" tall and weighs 115 to 154 pounds is within the normal weight range, overweight at 155 to 185 pounds, and obese at 186 pounds or more.

Obesity in the U.S. has been increasing steadily over the past two decades--by objective measures such as the BMI, one in three Americans is obese.

RAND's studies have found that severe obesity is increasing the fastest. Between 1987 and 2005, the prevalence of a BMI greater than 40 (about 100 pounds overweight) increased by 500 percent; the prevalence of a BMI greater than 50 increased by almost 1,000 percent.

Many physicians believe that clinically severe obesity is a rare pathological condition affecting only a fixed percentage of the population. But RAND's findings are consistent with the view of most epidemiologists that severe obesity is an integral part of the U.S. population's weight distribution — and as everybody gets heavier, the extreme group has the fastest growth rate.