Is obesity always dangerous? Research suggests maybe not

By Deborah Kotz, Globe Staff

Despite the all-out war we’ve waged against the obesity epidemic, Americans persist in growing increasingly larger, with two-thirds of us now overweight. But there’s a ray of sunshine in this dark cloud of doom: For some people, carrying 30 or even 50 extra pounds may not harm their health and may, in fact, even offer some health benefits.

Evidence for a phenomenon called the obesity paradox indicates that excess fat may be protective in those who already have heart disease or diabetes, and new research published this week in the European Heart Journal found that overweight heart patients had a lower risk of dying after being hospitalized with a heart attack compared with patients who were underweight or at a normal body weight.

Another study published in the same journal suggests that being physically fit can counteract the detrimental health effects of obesity, which is defined as having a body mass index of at least 30, or 180 pounds for a 5-foot, 5-inch person. Obese folks who follow the government’s recommended guidelines for exercise -- walking moderately for 30 minutes five days a week -- had similar cholesterol, blood pressure, and blood sugar levels as those who weren’t overweight with about the same level of physical fitness.

“We’ve been studying this for a long time and have shown many times that obese people who are fit have no increased risk of dying earlier,” said Steven Blair, a professor of public health at the University of South Carolina who co-authored the second study. “But now we see that fitness is clearly associated with metabolic risk factors that make people healthy.”

That’s comforting news to those who work out hard only to find that those excess pounds stubbornly remain. In fact, researchers have demonstrated time and again that exercise is a crummy way to lose weight unless it’s combined with a reduced-calorie diet.

Even those who achieve substantial weight loss through diet and exercise frequently wind up putting those pounds right back on -- often due to physiological factors such as increased appetite and a slower metabolism -- and may get so frustrated that they quit exercising and return to Big Macs and shakes.

That’s a shame, said Blair, who’s obese despite being an avid runner for 40 years. “My blood sugar is fine, but I take medications for high cholesterol and high blood pressure.” He considers his daily workouts to be akin to drugs.

“I think physicians need to prescribe exercise just as they would any drug,” said Blair, “rather than telling patients to lose weight, which we know is tough or even impossible for some.”

While Blair admitted that he’s biased from his personal experiences, his co-author, Timothy Church, director of preventive medicine research at Pennington Biomedical Research Center, agreed that doctors -- and patients -- put too much emphasis on the scale.

“You may not lose a ton of weight, but you will lose around your waist where it matters,” Church said. Fat tissue around the midsection is usually more harmful than fat on the hips and thighs because it releases high amounts of inflammation chemicals associated with diabetes and heart disease.

Obese study participants who were physically fit had an average waist size that was two inches smaller than their counterparts who were obese and out of shape, despite having a similar percentage of body fat. Strength training two or three days a week is also important for improving fitness and, according to a recent study, can decrease diabetes risk just as well as steady cardiovascular exercise.

Genes, of course, play a leading role in determining whether we’ll develop heart disease, diabetes, or certain cancers -- regardless of our weight. Church said he saw a patient Wednesday whose blood pressure was sky-high, even though he was on several medications and he was thin. “If you come from a family with a lot of diabetes or early onset heart disease,” he said, “you’re at high risk, but being fit reduces that risk.”

In fact, he would argue that exercise delivers the biggest benefits in those who have these genetic predispositions. The same could be said for following a healthy diet based on fruits, vegetables, and lean protein rather than one filled with hot dogs, fries, and doughnuts.

Getting physically fit and eating well can lower your risk for disease even if, like Blair, you still consider yourself fat.

It’s still ideal, however, to be at a healthy weight and physically fit, despite research indicating that an obesity paradox may exist in those who are sick. “I think the jury is still out on that,” said Church, “but it could be that those who develop heart disease or diabetes despite being at a healthy weight have a stronger genetic predisposition working against them.”