Can you be Fat and Fit?

Many of us would describe the ideal runner’s body as lean, lanky and lithe. But then someone who is none of these things blows past us in a 5K, leaving us questioning what ‘fit’ really looks like.

Some doctors say people who are overweight (with a body mass index – or BMI – of 25-29.9) or obese (with a BMI of 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, director of the Healthy Lifestyles Research Centre at Arizona State University, US, says you can be fit and fat. Amy Weinstein, an assistant professor at Harvard Medical School, US, who studies the impact of obesity and exercise on disease, disagrees. Here’s why.

Is it possible to be overweight and healthy?

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 20-30 minutes a day, three days a week. Glenn Gaesser

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 with regard to diabetes and cardiovascular disease. The reason for this is unclear. It may be that the particular hormones and proteins that regulate weight and affect chronic diseases cannot be adapted by physical activity. Amy Weinstein

But can a potbellied runner really outrun a lean machine?

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. GG

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

Should runners disregard age-related weight gain?

To control your weight as your metabolism slows down, you probably have to double your exercise. After you hit 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 40 years old, 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. GG

As your weight goes up, so does your risk of all sorts of chronic diseases. So I tell patients whose weight may have been steadily inching up to not concentrate on weight loss. Rather, let's first stop the weight gain. Even if it's just one pound a year, that's 20 pounds in 20 years, which is significant. AW

On the next page: Is eating less calories the best way to lose weight and which is more important, diet or exercise?

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

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. AW