The idea that people can be overweight and yet still quite healthy began gaining scientific and popular credence some years ago, fueled by the publication of a number of studies showing that men and women who were a few pounds overweight but physically active had less risk of developing cardiac disease than people who were of normal weight but sedentary.
Some scientists and doctors began speculating that healthy people who were sporting extra pounds didn't necessarily need to worry about losing weight. As one researcher told a reporter in 2004, "If a fat person or obese person has normal blood pressure, if their total cholesterol and glucose levels are normal and they are healthy, there is no reason they should necessarily have to lose weight."
But several new studies are raising questions about that comforting notion at a very inopportune moment, with the holiday overindulgence season barely behind us. In the most recent of these studies, published online on Dec. 28 in the journal Circulation, Swedish researchers examined medical records reaching back 30 years for a group of more than 1,700 middle-aged men in the city of Uppsala.
The men were measured and tested when they reached the age of 50 and then periodically for the next 30 years. They were categorized into groups based on their body-mass indexes and metabolic profiles, a good marker of overall physical health and fitness. Some were normal weight; some overweight (meaning they had a body-mass index of 25 or above); some obese (a B.M.I. greater than 30). In each of these groups, some had normal metabolic profiles, while others were afflicted with a variety of conditions known collectively as metabolic syndrome. A diagnosis of metabolic syndrome means that you suffer from three or more of these conditions: impaired ability to handle blood sugar, high blood pressure, elevated blood fats, low HDL ("good" cholesterol) and a large waist circumference.
To no one's surprise, the Swedish researchers found that being overweight or obese and having metabolic syndrome was quite unhealthy. Overweight men in that group had a 74 percent higher risk of developing cardiovascular disease by the time they turned 80. Obese men with metabolic syndrome had a 155 percent higher risk. Even being of normal weight, if you had metabolic syndrome, was dangerous. Men in this group, with normal girths but poor cholesterol and blood-pressure readings, had a 63 percent higher risk of developing heart disease than normal-weight men without metabolic problems. In other words, you don't want to have metabolic syndrome, even if you're thin.
More startling, though, was the study's finding that being overweight with no evidence of metabolic syndrome left you at significantly higher risk for heart disease than if, with the same metabolic readings, you were not overweight. Men who were overweight (not obese) with healthy blood pressures, cholesterol readings, blood glucose levels and so on, still had a 52 percent higher risk of developing heart disease within 30 years than men who were normal weight and had similar metabolic profiles. That risk rose to 95 percent among obese men who didn't suffer from metabolic syndrome.
The researchers did not report on the activity levels or exercise practices of any of the men, but typically more-active people have healthier metabolic profiles and vice versa. The findings did make it clear that although being fat and having healthy blood work puts you at less risk of cardiac disease than someone who is thin and has lousy metabolic parameters, the extra pounds still leave you with at least a 50 percent greater risk of developing heart disease.
"Previous studies have put forward the existence of a 'metabolically healthy' subgroup" of overweight people "who are at no increased cardiovascular risk," Johan Arnlov, Ph.D., an associate professor at Uppsala University and the study's lead author, said in a statement. But "if you follow them long enough, you find out there appears to be no such thing as metabolically healthy" extra poundage. (To assess your B.M.I., plug your height and weight into this calculator from the National Heart, Lung and Blood Institute.)
Another recent large study found somewhat similar results among women, although it looked at activity levels, not metabolic profiles, to assess health and fitness. That report, published in 2008, used data on almost 40,000 women enrolled in the Women's Health Study. Its authors found that women with a higher B.M.I., even if they were active, had an elevated risk of coronary heart disease compared with women engaging in an equal amount of activity who were of normal weight. Being fit, for the thousands of women under consideration here, lessened but did not fully mitigate the health problems associated with being fat.
Then there are football players, a group -- particularly the linemen -- who would seem to be advertisements for hefty-size health and fitness. But according to a study presented in October at the Annual Scientific Meeting of the American College of Gastroenterology, when scientists studied current N.F.L. linemen, they found that those athletes had a significantly greater incidence of metabolic syndrome than a group of less-bulky professional baseball players.