CHAPEL HILL -- Most New Year's resolutions to lose weight fail, as millions of guilty dieters nationwide can attest, but if you think there's no harm in having love handles once you reach 50 or 60, guess again.
A University of North Carolina at Chapel Hill nutrition expert says new research shows the best weight for a 60-year-old is the same as for a 30-year-old and, health-wise, thin is definitely in.
Dr. June Stevens, associate professor of nutrition and epidemiology at the UNC-CH schools of public health and medicine, was principal investigator for one of the largest, most definitive studies ever done on obesity's impact on survival. A report on the findings appears in the Jan. 1 issue of the New England Journal of Medicine.
"Our new study, which involved almost a third of a million subjects, showed that excess body weight increased the risk of death from heart disease and other causes up until late life, and there was no change in the weight associated with the best survival until age 75," Stevens said.
Researchers analyzed deaths among healthy white women and men who participated in the American Cancer Society's Cancer Prevention Study-I. None of the subjects had ever smoked, was sick or had a history of heart disease, stroke, cancer or recent unintentional weight loss. Those who died in the first year of data collection were excluded, and researchers controlled for age, education, physical activity and alcohol use.
Although body weight associated with the longest life did not change, the risk of excess weight was higher in younger adults than in middle-aged and older adults, the study showed. But interpreting risk in people of different ages is tricky, Stevens said.
"Age is the ultimate risk for death -- most any risk factor is going to look small in comparison to old age," she said. "Optimal weight at various ages has been a hotly debated topic with lively exchanges between eminent scientists with divergent views.
"U.S. Department of Agriculture Dietary Guidelines came out in 1990 saying it was all right for people over age 35 to be heavier than younger adults," Stevens said. "In 1995, new USDA guidelines were issued but with age-specific weight recommendations omitted. Both sets were criticized for various reasons."
The new research uncovered the fewest deaths among people ages 30 to 74 who had a body mass index -- an obesity measure -- of between 19 and 22. In other words, those between 90 percent and 100 percent of the 1983 Metropolitan Life Insurance index of ideal weights lived longest. By comparison, a typical female fashion model has a body mass index of about 18.
Optimal weight for a five-foot- four-inch woman would be between 111 and 128 pounds, for example, and for a five-foot-10-inch man, between 133 and 153 pounds. A five-foot-10-inch man between ages 30 and 44 faces a 20 percent higher risk of death if he weighs 166 pounds than if he is 20 pounds lighter.
Although the new study showed that thinner adults lived longer, Stevens hesitated to urge excessive dieting.
"With the methods we have available now, most people can't attain and maintain such a slender weight," she said. "Although it appears that low weight contributes to longer life, perhaps the best New Year's resolution for most Americans is to vow not to gain one more pound beyond what they weigh today. If the public could achieve that more modest goal, it would have a tremendous impact."
Earlier studies have underscored obesity's prevalence in U.S. society
In a nationally representative study of Americans known as NHANES III, 52 percent of women ages 50 to 59 were overweight, while only 20 percent of women in their 20s were. Another large multicenter study of atherosclerosis risk (ARIC), based partly at UNC-CH, found only about a quarter of U.S. adults gained less than 10 pounds between age 25 and late adulthood -- ages 45 to 64.
"Weight gain throughout early and middle adulthood is actually the norm, but it's probably not a very healthy norm," Stevens said.
The new study cannot be used to draw conclusions about weight change, she said.
"We did not study weight change, but just weight at one age, and then subsequent life span. We don't know if the people we studied gained weight, lost weight or stayed the same. We don't know if the heavy people had been heavy all their lives or had gained weight as they aged."
Although the data was not gathered recently, the work has several major strengths, the scientist said. One is that the sample size is so large. Another is that researchers excluded people whose health was suspect.
"The bottom line is 'weigh less and live longer' up until about age 75," she said. "After that, a little extra weight appears not to be a disadvantage. Unfortunately, it looks like you have to wait until you're 75 before you can enjoy a guilt-free piece of holiday fudge."
Besides Stevens, UNC-CH authors are Dr. Jianwen Cai, assistant professor of biostatistics, and statistician Joy L. Wood. Other authors, all epidemiologists, are Drs. Elsie R. Pamuk of the National Center for Health Statistics, David F. Williamson of the National Center for Chronic Disease Control and Prevention and Michael J. Thun of the American Cancer Society.
Note: Stevens' office numbers are (919) 962-2756 and 966-1065. She can be reached at home Dec. 25-26 at (919) 967-3609; in New Hampshire Dec. 27-30 at (603) 526-9303 and in Maine Dec. 30-Jan.3 at (207) 384-5546. E-mail: <June_Stevens@UNC.EDU>
Contacts: David Williamson, Brett Johnson, (919) 962-2091.
Journal
New England Journal of Medicine