At 5 feet, 7 inches and 127 pounds, Sarah Cooper is so thin that co-workers nicknamed her Olive Oyl. Naturally, then, she was startled to discover that according to a study released 10 days ago, her risk of dying is 20% higher than that of a woman the same age and height who is a few pounds lighter.
"Wow, it's pretty amusing that even I bombed out," Cooper said, referring to the scale of mortality and weight developed by the researchers.
The 37-year-old La Habra resident was not alone in her dismay at the heavily publicized Harvard Medical School study of more than 100,000 middle-aged female nurses, which included the zinger that the "lowest mortality rate was observed among women who weighed at least 15% less than the U.S. average."
Reacting to that news, many women expressed frustration that the ideal weight appears to be an ever-receding goal, about as attainable as the pot at the end of a rainbow. And given American culture's sometimes dangerous and often inane idealization of slimness, it seemed that for Harvard physicians to promote the same image was to heap insult upon injury.
Although many experts said the study was perfectly sound and much welcome, especially because one in three Americans is obese, some researchers criticized the study, even saying it was irresponsible for not paying more attention to body shape and the ratio of fat to muscle.
They cite previous work suggesting that lower body fat in "pear-shaped" people is less dangerous than upper body fat, not to mention muscular, physically active people who may be above the ideal weight but are probably healthier than most.
"Not all fat is equal," said Judith S. Stern, a UC Davis nutritionist who headed an Institute of Medicine study of obesity that was released last spring. "If your weight was lower-body weight, and you had no family history of heart disease, you may not need to focus so much" on the study's optimum weights.
Kelly Brownell, a psychologist and director of the Yale Center for Eating and Weight Disorders, does not criticize the study, but is concerned that some people may take a "be skinny at all costs" message from it. "In some ways, it's bad news," he said. "There's already tremendous pressure on people to be lean, and this creates even more."
The recent outbreak of anxious misunderstanding reflects a basic quandary of life in the Era of the Worried Well: translating masses of data from elaborate population studies into simple lessons to live by.
To a researcher steeped in statistics, the Harvard study's finding that a 5-foot, 5-inch woman minimized her death risk by weighing 119 pounds or less is a useful abstraction. But to a woman hoping to maximize her health and longevity, the very precision of that conclusion appeared to give it the force of doctor's orders to lose weight--or else.
"Should a middle-aged woman keep losing weight until she's 15% less than the average? Certainly not," Stern said. "What the study suggests is that a person might be healthier if some weight is lost."
The Harvard study, published in the New England Journal of Medicine, was directed by Dr. JoAnn E. Manson, an endocrinologist who is co-director of the Women's Health Center at the Brigham and Women's Hospital in Boston.
Delving into a continuous health survey of 115,195 nurses who were 30 to 55 years old when the study began in 1976, Manson and her co-workers found that 4,726 had died. Predictably, the great majority of deaths were among the oldest women.
Next, the researchers sorted all the women into seven weight categories ranging from very thin to morbidly obese. And, to highlight the effects of body weight per se, they focused on women who neither smoked nor gained a lot of weight since early adulthood.
They found that compared with the thinnest women, those who weighed successively more had higher mortality rates. A 5-foot-5 woman's added mortality risk was 20% at 122 pounds; 30% at about 140 pounds; 60% at 170 pounds, and 100%, or twice the mortality risk, at 180 pounds. "Even women with average weights had higher mortality" than the skinniest women, the researchers concluded.
Although the study has generated much debate over the dangers of being moderately heavy or even average in weight, it has firmly settled one key issue. In previous research, the thinnest people generally had a higher death rate than those of moderate weight. That raised the possibility that skinniness was unhealthy. But Manson and co-workers showed that observation to be largely the result of smoking, which lowers weight and causes death.
So far, so good. But when non-scientists try to use precise study data to understand their own chances of survival, it gets puzzling.