Can You Be Fit and Fat?

April 30, 2011— -- Many of us would describe the ideal runner's body as lean, lanky, lithe. But then someone who is none of those things blows past us in a 5-K, leaving us questioning what "fit" really looks like. Some doctors say people who are overweight (body-mass index, or BMI, of 25 to 29.9) or obese (BMI above 30) will face health issues, regardless of how often--or fast--they run. But some studies show that heavy people who exercise can be cardiovascularly healthy and may live longer than their sedentary but skinny peers.

We asked two experts to, ahem, weigh in. Glenn Gaesser, Ph.D., director of the Healthy Lifestyles Research Center at Arizona State University, says you can be fit and fat. Amy Weinstein, M.D., M.P.H., an assistant professor at Harvard Medical School who studies the impact of obesity and exercise on disease, disagrees. Here's why.

Is it possible to be overweight and healthy?

Yes

Virtually every weight-related health problem can be greatly improved or cured with a moderate level of exercise, even if you're overweight. The amount of exercise necessary to achieve a fitness level that greatly reduces disease and mortality risk is the equivalent of brisk walking for 30 minutes a day, five days a week, or running 20 to 30 minutes a day, three days a week.

No

Based on research I've seen and studies I've performed, it appears that physical activity cannot completely reverse the ill effects of carrying excess weight on diabetes and cardiovascular disease. The reason for this is unclear. There may be hormones and proteins that regulate weight and affect chronic diseases, which physical activity cannot reverse.

But can a butterball really outrun a lean machine?

Yes

It's possible for a heavier runner to be faster than a thinner runner if the heavier runner has the necessary ingredients for better endurance: higher VO2 max, higher lactate threshold, and better running economy. Genes play a huge role as well, as does experience.

No

Well, sure, it's not impossible. But a person who is overweight would be faster if he lost weight. A loss of about two pounds will theoretically increase speed by about a meter per minute of running. So if a runner runs a 5-K in 20 minutes, a two-pound weight loss would make him five seconds faster overall.

Do heavy runners get injured at the same rate as thin runners?

No

Being overweight increases your risk of arthritis. Research shows that obese people have almost three times the risk of arthritis in the knees. So it would make sense that heavy runners are at a higher risk of injuring their joints.

Should runners disregard age-related weight gain?

Yes

To control your weight as your metabolism slows down, you probably have to double your exercise. After age 40, you'd need to run about two more miles per week, each year, in order to maintain your weight. So if you are running 25 miles a week at age 40, you'd have to do 27 miles at 41, 29 miles a week at 42, and so on. That might be more than most people are willing to do. That's why I promote physical activity for health and not for losing weight, because it takes a lot. If your weight is creeping up but your cholesterol and blood pressure stay in the healthy range, I wouldn't worry about it.

No