Researchers from the Centers for Disease Control and Prevention and the National Cancer Institute checked death records for 37,000 adults, along with age and weight, and found that people who were overweight (for someone who is, say, 5' 4", that means weighing 145 to 169 pounds) had no greater risk of dying from cancer or heart disease than those who were of normal weight (for a 5' 4" person, 110 to 144 pounds). Even more remarkable, the overweight group was less likely to die from a host of other conditions, including chronic respiratory disease, infections, and Alzheimer's or Parkinson's disease. While being overweight left people at higher risk of death from diabetes and kidney disease, as a group, people in the overweight category outlived the obese, the underweight, and people at normal weight.
Although lead study author Katherine Flegal, PhD, a senior research scientist at the CDC, and her colleagues did not look at why being overweight could have a protective effect, they hypothesize that extra pounds might provide the body with a reserve during illness and recovery from major operations.
The results have provoked some strong reactions. "This research should be completely disregarded," says Walter Willett, MD, professor of epidemiology and nutrition at the Harvard School of Public Health. He points to other large studies that have found that being overweight can shorten life. But, says Flegal, this research used self-reported weights. If subjects shaved pounds off their actual size, obese people could have dropped into the overweight category. But for most critics of the new research, quality of life is a major sticking point: Just because someone lives longer doesn't mean they spent that time free of pain and disease. Flegal's research didn't analyze quality of life. But you can live those extra years in good health regardless of your weight, believes Steven Blair, a professor of exercise science, epidemiology, and biostatistics at the University of South Carolina. He published a study in December that suggests overweight people who are active and fit have a lower mortality risk than their out-of-shape, normal-weight peers. "These studies show that the hazards of being overweight, in terms of mortality, have been exaggerated," he says. "We need to rethink the description of the overweight group."