= Full article availableA recent headline in Time magazine asked the question many Americans are wondering in the wake of a controversial study by the National Cancer Institute and the Centers for Disease Control and Prevention (CDC): “Is it OK to be pudgy?” The study, published in the Journal of the American Medical Association (JAMA), is among the most rigorous yet to look at the relationship between weight and mortality. To the bafflement of many scientists and the consternation of America’s $46 billion-a-year diet industry, it found that people who are overweight but not obese have a lower risk of death than those of “normal” weight, as defined by the government using Body Mass Index (BMI).
The study found an increased risk of death only for those with a BMI of 30 and above. An average-height woman, at 5-foot-4, would have to weigh 175 pounds to reach that risk group; an average 5-foot-9 man, 203 pounds.
But the study also found that the Duchess of Windsor, who famously said you can never be too rich or too thin, was only half right: The thinnest two percent of the population, with BMI below 18.5 (107 pounds at 5-foot-4, 125 pounds at 5-foot-9), showed the same mortality risk as the very fat. Though careful not to imply cause-and-effect relationships, the researchers estimated 33,000 additional deaths annually among this ultra-skinny group.
The report also cut the estimate of obesity-related deaths to 112,000 annually—a fraction of the much-publicized CDC number of 400,000 released just a year ago.
So is it time to break out the Big Macs?
Before you start pondering your reply to “Would you like fries with that?,” it’s worth digging a little deeper. First, the difference in mortality risk between the normal-weight (18.5-24.9 BMI ) group and those modestly overweight (25-29.9) was small. So if you’re a bit under 25 BMI, there’s no need to gain weight to live longer. (To calculate your own BMI, see the CDC’s BMI calculator.)
Nor do the researchers know why being modestly overweight might be linked to reduced mortality—though this is not the first such study to associate being overweight with a slight drop in mortality risk. The CDC’s David F. Williamson, PhD, a study co-author, suggests one explanation: Most people die after age 70, and in the elderly a little extra fat gives rise to more bone and muscle, which can be protective against medical crises. It could also be, the researchers say, that the negative effects of being overweight “may have decreased over time, perhaps because of improvements in public health and medical care.”
The study looked only at death rates, not the impact of weight on risk for serious ailments such as diabetes or heart disease. And it’s difficult to untangle weight from other causes of death.
Critics, including experts at the American Heart Association and American Cancer Society, fault the study for including people with serious diseases. Conditions such as cancer or heart disease often cause people to weigh less—and make heftier people look healthier by comparison.
The CDC even held a press conference to apologize for any “confusion.” “It is not OK to be overweight,” said director Julie Gerberding, MD, MPH. “People need to be fit, they need to have a healthy diet, they need to exercise.”
And the ink was barely dry on that issue of JAMA before a major new study from the University of Pittsburgh re-emphasized the dangers of being extremely obese. Researchers looked at five years of data on 90,000 American women in the Women’s Health Initiative Observational Study. White women with 30-34.9 BMI had a 19 percent greater risk of death than normal-weight women; those with a BMI of 40 or above saw a doubling in risk. The added risk for black women was 36 percent, 60 percent for the most obese. “Apple-shaped” women, with extra fat around the middle, were at greater risk than those carrying fat in their hips, buttocks and thighs (“pear-shaped”).
The good news from the Pitt study, though, is that losing even 20 pounds improved the women’s mortality risk.
Mortality statistics aside, volumes of studies have linked being obese to added risk of everything from heart disease to sleep apnea. An analysis of nationally representative data from the NHANES II study by Tufts University researcher Aviva Must, PhD, published in the Journal of the American Medical Association, concludes, “The health consequences of obesity are substantial, with type II diabetes, heart disease and gallbladder disease among the more common obesity-related diseases.” Must also points out the benefits of shedding extra pounds: “Fortunately, mounting evidence indicates that many of the health risks associated with obesity can be reversed with weight loss.”
But losing and then regaining weight can have its own risks, she warns. Fluctuations in weight have been linked to increased risk of developing chronic diseases and excess mortality.
So your best strategy is probably Aristotle’s admonition of “moderation in all things.” A landmark National Heart, Lung and Blood Institute (NHLBI) report warned against going overboard about BMI back in 1998: Among those with 25-29.9 BMI (technically, “overweight”) and 30-34.9 (“obese”), it found, waist size also mattered. If you’re in those categories but your waist measures less than 35 inches (for women) or 40 inches (for men), your risk of developing obesity-related ailments such as type 2 diabetes is less than for those with the same BMI but bigger waistlines. For those in the “overweight” category with trimmer waistlines, the NHLBI advised working on weight loss only if you also have two or more additional risk factors (high cholesterol, blood sugar or blood pressure). Otherwise, concentrate on not gaining any more weight.
Sorry, that still means watching the cheeseburgers.
Interested in more articles like this? Subscribe or order this issue.