Athletes with a low-carb diet burn more fat because of the lack of carbohydrates cells can convert to glucose for energy. Photo by Naatali/Shutterstock
COLUMBUS, Ohio, Nov. 17 (UPI) -- Many athletes carb-load before a workout or event to increase the amount of energy stored in their body. Researchers at Ohio State University, however, found athletes who "go against the grain" by instead cutting carbohydrates out of their diet burn more than twice as much fat as those who don't.
Researchers compared fat-burning in endurance athletes who'd already been living on a ketogenic diet -- one with highly restricted carbohydrates -- with athletes who observe the standard carb-loading system for extra energy, finding a clear benefit to cutting back on carbs.
Dr. Jeff Volek, a professor human sciences at OSU who led the study, said the research reveals the human body can burn much more fat than some think, however in the presence of carbohydrates that fat does not get burned.
Lowering carbohydrates in the body forces it to access fat stores, converting fats into ketones, which are used by cells as an alternative to converting glucose into energy.
"This represents a real paradigm shift in sports nutrition, and I don't use that term lightly," Volek said in a press release. "Maybe we've got it all backwards and we need to re-examine everything we've been telling athletes for the last 40 years about loading up on carbs. Clearly, it's not as straightforward as we used to think."
The researchers worked with 20 ultra-marathoners and ironman distance triathletes, half of whom consumed a traditional high-carbohydrate diet while the rest had observed a low-carbohydrate ketogenic diet for an average of 20 months.
The athletes participated in a two days of testing with the researchers. During the first day, the athletes ran on a treadmill to determine their maximum oxygen consumption and peak fat-burning rates. On day two, the athletes were asked to run for 180 minutes at 64 percent of their maximum oxygen capacity after consuming either a low- or high-carbohydrate nutrition shake.
The difference in fat-burning between the two groups of athletes was significant: The low-carb group had an 88 percent fat-burning rate, while the high-carb group was at just 56 percent. Volek said although both groups were in peak physical condition, the low-carb diet clearly allowed that group of athletes to force their body into burning much more fat than the high-carb group.
"The goal was to characterize their metabolic response to a standardized exercise test," Volek said. "This is the first time we've had the opportunity to peek under the hood at what a long-term low-carb, fat-adapted athlete looks like."
The study is published in the journal Metabolism: Clinical and Experimental.