Fat but fit

Surprisingly, some obese people seem to be as metabolically healthy as their normal-weight peers

Fat but fit

Andy Richter/Aurora Photos/Corbis

Fat but fit
Andy Richter/Aurora Photos/Corbis

Ragen Chastain, who carries 284 lb. on her five-foot, four-inch frame, has been an athlete since she was a kid: she was cheerleading captain, a varsity athlete and has won three national championships as a competitive country and western dancer. “I focus on my fitness as a dancer, I get my five servings of fruits and vegetables a day and make healthy choices,” says Chastain, 35, who lives in Los Angeles. She isn’t our typical picture of health. With a body mass index of 48, Chastain classifies as morbidly obese. (BMI is a measurement of body fat based on weight and height; 25 or greater qualifies as overweight, and 30 or greater is obesity.)

Obesity has been linked to all sorts of serious health problems, such as hypertension, heart disease and Type 2 diabetes. But not all obese people are alike. Surprisingly, some seem to be as metabolically healthy as their normal-weight peers—maybe even more so. The notion that it’s possible to be “fit but fat” is still very controversial. “I think it can be misinterpreted to suggest that obesity doesn’t matter in many people,” says Robert Ross, an expert in exercise physiology at Queen’s University. “I’m as fat as you can get on the BMI chart,” acknowledges Chastain, author of Fat: The Owner’s Manual. She believes it says little about her overall fitness and health. On her blog, Dances With Fat, she writes: “I am not a thin woman covered in fat, I am a fat woman who is also a very fit athlete.”

A new study in the European Heart Journal, the largest one ever to examine this, suggests just how common these “fit but fat” people might be. Over 43,000 participants were given a detailed questionnaire and physical exam, including a treadmill test. Researchers concluded that 46 per cent of obese participants were metabolically healthy: they didn’t suffer from conditions like insulin resistance, diabetes, high cholesterol or high blood pressure. (To qualify as “metabolically healthy” in this study, they could have one or none of those conditions.) These people were at no greater risk of death from any cause than those who were of normal weight—in other words, their excess pounds didn’t seem to make a difference.

Dr. Arya Sharma, who holds the Obesity Chair at the University of Alberta, has seen it in his clinic. He’ll sometimes encounter patients with severe obesity, “and when you do all the tests, they’re pretty healthy. They’re probably healthier than you or me.” These people tend to have healthier lifestyles, diets, are physically active, “and quite happy with themselves,” he says, instead of suffering from depression or low self-esteem.

A second study in the European Heart Journal looked at the “obesity paradox.” While being overweight is itself a risk factor for a host of health problems, the paradox is that once overweight people become sick, they actually seem to have a survival benefit over their less heavy counterparts. The study drew on data from over 64,000 patients in a Swedish registry, and found the relationship between BMI and mortality from any cause was u-shaped. “Patients who are underweight have the worst prognosis, and normal-weight people have a worse prognosis than the overweight,” says Dr. Oskar Angerås, consultant cardiologist at the University of Gothenburg. “Once your BMI is over 35, it’s trouble again.” Those with a BMI between 30 and 35, who qualify as obese, “have the best prognosis.”

More new research, presented at the European Society of Cardiology Congress in Munich, examined the opposite of being fit and fat: people who are of normal weight (a BMI between 18.5 and 25) but carry excess pounds around the waistline, sometimes called the “thin-fat phenotype.” A team led by Dr. Francisco López-Jiménez of the Mayo Clinic in Rochester, Minn. surveyed over 12,785 Americans for their height, weight, waist and hip circumference, as well as their socio-economic status and other factors. Normal-weight people with fat packed around their middles were at highest death risk from all causes—higher than the obese. “I think it’s been surprising for many people,” López-Jiménez says. “It may change the standard of how we assess obesity. It’s not just about BMI, or weight on the scale.”

Where we put on fat seems to be more relevant to our health than how much of it we carry. “Body shape is more important than body size,” says obesity expert Jean-Pierre Després, director of research, cardiology at the Québec Heart and Lung Institute. People who are “apple-shaped,” with fat gathered at the belly, seem to be at higher risk than those who are “pear-shaped,” carrying excess fat on the hips and thighs. This message is catching on: the Heart and Stroke Foundation now has guidelines for a healthy waist circumference in addition to BMI.

Visceral fat, which packs around the abdomen, has all sorts of harmful effects, releasing free fatty acids and inflammatory substances through the body. It’s also associated with having an excess of fat in the liver and around the heart, increasing the risk of diabetes and heart disease; Després says that it’s a sign the body’s fat deposits are being stored in the wrong places. Even thin people can carry too much visceral fat around their guts, whereas fit fat people, such as Sumo wrestlers, have been shown to have very low levels of it, says E. Louise Thomas of the Metabolic and Molecular Imaging Group at Imperial College London. Subcutaneous fat, the soft pinchable stuff, is comparatively harmless.

Scientists haven’t figured out why some people tend to gather fat around the waistline as opposed to the hips and thighs, where it seems to have a protective effect. Genetics almost certainly play a role, but Thomas believes that lifestyle is more important.

“Studies have shown that fat people tend to have fat dogs,” she says. “If there was a strong genetic determinant, fat people wouldn’t have fat dogs. That points to environment and culture.” (Fat people don’t tend to have fat cats, though, because cats aren’t as dependent on their owners for exercise.)

Exercise seems to be the main differentiating factor. In that first European Heart Journal study, metabolically healthy obese people had better cardiorespiratory fitness than the unhealthy obese, lead author Francisco Ortega of the University of Granada says. When we exercise, visceral fat (including liver and heart fat) is the first fat to go, as Després has shown. He took a group of sedentary, abdominally obese men and put them on an exercise program under his supervision for three years. They lost “a tremendous amount” of dangerous fat around their waistlines, even if they didn’t drop a pound.

Ross cautions that the notion of “metabolically healthy obesity” has to be handled with great caution. “I’m positive the investigators who make these observations are not intending to suggest obesity is a good thing—that ‘You’re okay, don’t worry about it.’ ” The percentage of obese people who are “healthy” is actually very low, he notes (another study from York University found that about six per cent of obese individuals had no metabolic risk factors). Even if an obese person’s blood pressure or cholesterol levels are in check, they might suffer from other problems, he says, like osteoporosis, back pain, or depression—or they might go on to develop common metabolic risk factors later.

The longevity of healthy obese people is still largely unknown, notes Patrick Bradshaw, an epidemiologist at the University of North Carolina at Chapel Hill who studies obesity as it relates to chronic disease. In one study, he followed healthy individuals for about nine years, and found the obese were at much greater risk of developing full-blown metabolic syndrome (three or more risk factors like high blood pressure, high waist circumference and high blood sugar), suggesting problems can develop with time.

Whether someone is fat and fit, “thin-fat,” or obese and unhealthy, exercise seems to be key in avoiding the buildup of visceral fat—even if it doesn’t melt pounds away. Overweight and obese people who take up an exercise program, but don’t see their bodies drastically change, shouldn’t be discouraged: it’s likely they’re becoming fitter even if they’re still fat. “We somehow equate size to health. The idea that everyone could have a BMI of 25 is nonsense,” Sharma says. “And the idea that if we were all a BMI of 25, we’d be perfectly healthy, is also nonsense.”