Should Marathon Runners Change Their Diet to Lose Weight?

Should Marathon Runners Change Their Diet to Lose Weight?

Have a question about running? You’re in the right place. Every Tuesday, world-renowned coach, author and athlete Hal Higdon posts and answers athlete questions here. You can submit your question by joining the discussions on Hal Higdon’s Virtual Training Bulletin Boards.


Twelve weeks into my marathon training program, I decided to switch to a high protein, low carbohydrate diet to lose weight. On Tuesday, I ran 4 miles at a slow pace. Wednesday (which was very hot) was slower yet. Thursday, it was cooler, so I ran 5 miles, also slow. During the week I lost 8 pounds! I plan to eat good carbs leading into the weekend long run, then try to watch my calorie count to maintain my weight loss, hoping that lighter will make me faster.


Eight pounds in less than a week by following a high-protein diet? I hate to disillusion you, but that is not a very healthy way to train. You lost those pounds, because a high-protein diet forces you to shed fluids, not a great idea during the summer when temperatures rise. Losing a few pounds because of a trick diet that forces you to sweat away fluids is easy; maintaining that weight loss is hard. I strongly advise that you get off that high protein diet and follow a diet that is 55% carbs, 30% fat and 15% protein. Most of those carbs also should be complex carbohydrates, the kind you find in fruits and vegetables and whole-wheat grains.

Rollercoastering between diets is never a good idea, whether while training for a marathon or not. Just as consistency in training works wonders, so too will consistency in eating. Carbo-loading should not come only before the weekend long runs, or before the race itself. Carbo-loading should be a permanent part of our lifestyles.

If still in doubt about diet, consult with a Registered Dietitian. RD’s are our sport’s number-one performance enhancers. 

Hal Higdon

Hal Higdon is a Contributing Editor for'Runner's World'and author of 34 books, including the best-selling'Marathon: The Ultimate Training Guide. He ran eight times in the Olympic Trials and won four world masters championships. Higdon estimates that more than a quarter million runners have finished marathons using his training programs, and he also offers additional interactive programs at all distances through TrainingPeaks.Hal uses'TrainingPeaks'to power his interactive marathon and half marathon training plans.'Check out more of Hal Higdon's training plans here'or on'his website.