From the April issue of Runner's World
Many of us would describe the perfect runner’s body as lean, lanky, lithe. But then someone who is none of those things blows past us in a 5K, 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 on exercise and disease, disagrees. Here’s why.
RUNNER’S WORLD 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.
RW But can a heavier runner 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 one kilogram will theoretically increase speed by about a metre per minute of running. So if a runner runs a 5K in 20 minutes, a one-kilo weight loss would make him five seconds faster overall.
RW Do the benefits of exercise matter more than losing weight?
YES Physical activity can lower your risk of cardiovascular disease, regardless of your weight. Whether you’re talking about boosting good HDL cholesterol, lowering bad HDL cholesterol, reducing blood pressure, and so forth – all these can be improved with exercise, even if you don’t lose weight. And this results in a lower cardiovascular-disease risk. Physical activity seems to have a profound effect on overall mortality risk as well – again, regardless of your weight.
NO Exercise can improve your health, but you can list more than 50 medical conditions – from diabetes to arthritis to acid reflux to sleep apnoea to certain cancers – that result from complications from carrying excess weight. Even losing three to five kilos will lower your risk of developing these issues and improve your health.