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Marathons & Weight Loss

BY Hal Higdon

I don't consider it a great idea to use a marathon as a means of losing weight, although I have met numerous people who have achieved success doing just that.

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.


How do you effectively lose weight while training for a marathon and still get enough calories for the long runs and the race itself? I am a month into my training, and I worry that I will not have enough energy to train properly, particularly as the long runs get longer and longer. I had hoped to lose 10-15 pounds before I even started, but that did not happen. Suggestions?


I don’t consider it a great idea to use a marathon as a means of losing weight, although I have met numerous people who have achieved success doing just that. I would prefer to see them begin to lose the weight, and only then take their tinier bodies to a marathon. Obviously that did not work for you, so let’s move on to Option # 2.

You already know that runners need a certain amount of calories to train properly, and a high percentage of those calories must come from complex carbohydrates. All my nutritional experts peg the best blend as 55% carbohydrates, 30% fats and 15% proteins. Low-carb diets may provide some immediate weight loss, but won’t provide much help over the long run.

The secret to weight loss while training for a marathon is to achieve a caloric deficit. Theoretically, if you burn 3,500 calories a day and consume 3,000 calories a day, this would create a 500 calorie deficit. Multiply that by 7 days and you achieve a 3,500 calorie weekly deficit, close to the 3,600 calories that cause the loss of one pound. That might get you down to the previously targeted 10-15 pounds weight loss.

Theory doesn’t always hold up, however. The less you eat and the more you run, the more the body conserves energy, particularly in runners who are lean and trying to get to their best “racing weight.” Weight loss is just not as mathematical and as linear as we would like it to be!

Your best bet is to “chip away” at weight loss by eating about 300 to 500 calories less at night. You need to fuel before, during and after your long runs, so you have the energy to train well and recover well. You can then eat less dinner and/or fewer evening snacks, and lose weight at night when you are sleeping. You do not want to lose weight when you are trying to train.

Also, consider consulting a Registered Dietitian, who can guide you in your weight loss plans. Short of that, the best book on the subject is Nancy Clark’s Sports Nutrition Guidebook. Good luck getting to the starting line with at least a few pounds shed, but if not, start that diet after you reach the finish line.

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About 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 over a quarter of a 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 on his website.