Their study, the first to compare the effects of these major health risks on morbidity, also provides new estimates indicating that three of every five adult Americans are either overweight (36 percent) or obese (23 percent). In fact, far more people now are overweight or obese than are, collectively, daily smokers, problem drinkers and below the federal poverty line.

The study is likely to reinforce the growing concern that obesity has become epidemic. It also underscores the top priority the Surgeon General is giving this year to developing a national action plan to reduce obesity's prevalence.

"Americans haven't given overweight the same attention as other risks, like smoking, but it is clearly a top health problem and one that is on the rise in all segments of the population. More effective clinical and public health approaches are urgently needed," declare co-authors Roland Sturm, a RAND economist, and Kenneth Wells, a psychiatrist on the RAND staff who is also on the faculty of the UCLA School of Medicine.

Sturm and Wells analyzed data from a nationally representative, household telephone survey of 9,585 adults conducted in 1998. The survey included questions covering height, weight, income, smoking and drinking habits and health status.

The researchers used the body mass index (BMI), a ratio of height to weight, to define overweight and obesity. (For example, someone who is 5 ft. 4 in. tall and weighs 174 lbs. or more or 5 ft. 10 in. and 209 lbs. or more is considered obese). They measured health status by analyzing responses to questions concerning some 17 major chronic conditions and 12 quality-of-life issues.

The study was funded by the Robert Wood Johnson Foundation. RAND is a nonprofit organization that improves policy and decisionmaking through research and analysis.

For a copy of the journal article, contact RAND customer service at order@rand.org.