Why Do Runners Gain Weight?

Weight loss is among the most common New Year’s resolutions, made and broken.

The idea of weight loss is relatively simple on the surface, but is by no means easy. You see, body weight is a mix of food kilojoules taken in, kilojoules burned throughout the day, and genetics/epigenetics (your genetic code and how your environment interacts with the code).

How do runners get overweight? Exercise boosts hunger and can give you the perception that being active means you can eat more, without gaining weight. Some runners also have medical issues, like low thyroid. Others don’t run as much as they say or think they do.

Runners generally get enough exercise for cardiovascular fitness, but every-other-day runners may not burn enough kilojoules to lose weight. Research says an hour a day of walking-intensity exercise is needed for some people, especially women, to lose weight. So, increasing the number of days and the number of minutes may be necessary for some runners.

Additionally, some runners might not invest enough time into strength training. Increasing muscle mass plays an important role in weight loss: Think of your muscle mass as engine size and quality – a race car burns more fuel than a VW Beetle, even when it’s idling. Likewise, increasing muscle mass with strength training three times a week helps you burn more kilojoules, both at rest and with activity.

What’s more, many runners are active for 30-90 minutes a day and sit the rest of the time. Sound familiar? Engaging in more activity throughout the day – even simply standing instead of sitting – is healthier than continuous sitting and may help with weight reduction. Walk and talk meetings or treadmill desks are some strategies to get you out of your seat.

But the factor that trips up most runners is kilojoule intake. It’s always easy to justify that extra cookie at snack time or second portion during meals when you’ve been exercising regularly. However, with age, muscle mass decreases, you don’t tend to push as hard, and you may not exercise every day. This adds up to extra weight over a few years.

Weight loss is a complex problem and the puzzle has an individual answer for each person. For many of us, the overconfidence that regular exercise rules and our kilojoule intake isn’t important leads to a false sense of security and extra kilos. If you’re mindful of the kilojoules you take in, you’ll likely win the battle of kilojoules out vs kilojoules stored.


About the Author
Dr. Roberts is a Professor in the Department of Family Medicine and Community Health at the University of Minnesota Medical School, U.S. He served as Medical Director for the Twin Cities Marathon and has authored many research and educational publications on sports medicine.

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