Everyone knows that it’s unhealthy to be very overweight. But what if you are obese but still relatively physically fit? Does being fit cancel out the health risks of being obese, or at least some of them? In other words, is it possible that being obese isn’t the real problem, but rather being unfit?
Although some obese people, as well as some researchers, make this claim, there are no easy answers to these questions. First, it’s hard to define the terms. Overweight and obesity are usually defined in terms of body mass index (BMI), which is an imperfect gauge of body fat. Physical fitness varies from person to person and by age. Fitness means different things to a dancer, lumberjack, mailman, or weight lifter. But for researchers, fitness is generally defined as cardiovascular (aerobic) fitness -- the ability to carry on a vigorous activity such as running or brisk walking for an extended period.
Obese people face many increased risks -- for diabetes, high blood pressure, and high cholesterol, all of which boost the risk for cardiovascular disease. Obese people also face an elevated risk for many types of cancer and several other diseases. Thus, obese people, almost across the board, have significantly lower life expectancy than leaner people.
However, there is some evidence that for obese people who are fit, the risks are less dramatic. For instance, in a study looking at more than 5,000 men and women (age 30 to 75), researchers at the University of North Carolina reported that being obese and being unfit both increase the risk for premature death, while fitness reverses some, but not all, of the increased risk associated with excess body fat.
Some of the best-known research on this subject comes from the Cooper Institute for Aerobics Research in Dallas. Its studies have reported that obese men who become fit lower their risks. Men who are obese and fit actually face lower risks than those who are lean but unfit. Therefore, when it comes to cardiovascular mortality, fitness may be more important than weight, at least for men.
Being sedentary and unfit are major contributors to being overweight and obese. And when overweight people start to exercise more, they usually lose weight (especially if they control their calorie intake) and lower their blood pressure and cholesterol levels. That’s why, in these studies, relatively few obese people are very fit. Most obese people don’t (or can’t) exercise much, and those who truly become fit tend to lose weight. Just because there are some fit, healthy obese people, you shouldn’t conclude that it’s healthy for most people to stay obese.
