Get Well+Being delivered to your inbox every Monday Morning.

Running a Marathon? Load Up on Fat
New research suggests carb-loading before a race isn’t the best way to energize. By Melissa Romero
New research suggests that carb-loading before a race isn't the bets way to energize. Photograph courtesy of Shutterstock.
Comments () | Published August 13, 2012

We’ve all heard this before: Before a race, load up on carbohydrates. It makes sense, since carbs are packed with energy, and we all know how much of that we need to run a marathon.

But results from a small study suggest that if you want to keep energy flowing, a carb-heavy meal isn’t necessarily the best thing to eat right before competition. In fact, the most beneficial meal is high in fat, not carbs.

For the study, eight male collegiate runners consumed high-carbohydrate meals (71 percent carbs, 19 percent fat, 10 percent protein) for three days leading up to their endurance test. Before the test, training was limited and performed at low intensity.

Four hours before the treadmill endurance test, the runners ate either a high-fat meal (55 percent fat) or a high-carb meal (70 percent carbs). In addition, three minutes before the test they either ingested a placebo jelly or a carbohydrate jelly, which has a higher rate of absorption than glucose and is typically found in sports drinks.

Each runner ran for 80 minutes on a treadmill at his marathon race pace. Then each ran until exhaustion at a speed that would deplete his glycogen levels. Runners were able to drink water during the test; the lab temperature was set at 68 degrees.

It turned out that when runners consumed a high-fat meal and carb jelly, their time to exhaustion increased significantly. Eating a high-fat meal and the placebo jelly also resulted in an improved running time over the high-carb meal, though not as long as the high-fat and carb jelly combination. These results occurred for seven of the eight runners.

Researchers determined that eating a high-fat meal before a race boosts one’s fat metabolism during exercise, allowing the body’s carbohydrate storage to be used later during a race. “Following three days of glycogen loading, a high-fat meal and subsequent ingestion of a small portion of carbohydrate jelly prior to exercise enhances the performance of athlete endurance training,” they said in the study.

The fully study is available in the journal Nutrients.


Fitness Healthy Eating Nutrition Studies
Subscribe to Washingtonian

Discuss this story

Feel free to leave a comment or ask a question. The Washingtonian reserves the right to remove or edit content once posted.
  • black57

    take the time ...real time to become keto-adapted and therewould be no need for carbophydrates in the equasion

  • Jonathan Swaringen

    Keto Adaption which takes around 2 weeks does indeed allow great performance. Read The Art and Science of Low Carbohydrate Living and The Art and Science of Low Carbohydrate Performance for details

    Performance is more focused on the exercise aspect while Living is more focused on using Low-carbohydrate for general health. Though it does go into the performance aspect some as well. Two great books.

  • By the way, if you've got a lot of excess glucose in your system it tends to be turned into fatty acids anyway, which is why someone on a high-carb diet tends to have high triglycerides. It's the body taking steps to save itself from excess glycation. (Unlike glucose, fat doesn't degenerate organs and tissues, believe it or not.) It'd make more sense to skip the middleman and go ahead and eat most of your energy as fat rather than put your body through all that excess insulin production when you're just going to wind up with most of it turned to fat in the first place. What little glucose your body needs for the few tissues that can't get energy any other way, it can already make without you eating it, which is why most of us don't die in our sleep from hypoglycemia.

  • I'm curious how this would have turned out had they had them on a high-fat, low-carb diet in preparation for the run, not just directly before the run. With enough time to fat-adapt, they might have had even better results. Four hours isn't long enough. (Four *days* isn't usually long enough.)

  • Danny J Albers

    You can find the answer to that by viewing Timothy Allen Olson's race results this year. He just broke Scott Jurek's record on the Western States 100 mile, and just won a 100k race the other day.

blog comments powered by Disqus

Posted at 03:30 PM/ET, 08/13/2012 RSS | Print | Permalink | Comments () | Blogs