'Sleep-low' diet may give athletes an edge

By Gretchen Reynolds, New York Times News Service  Strategically skipping bread, pasta and other carbohydrates at dinner might improve subsequent athletic performance, provided those low-carb meals are combined with the right types of workouts, according to a new sports nutrition study. Its findings undercut some entrenched ideas about how athletes should eat in preparation for endurance races. Many dietitians and coaches advocate heaps of carbohydrates at the training table. Carbohydrates, which break down during digestion into sugar, are the body’s first choice as fuel. But the body’s reservoir of stored carbohydrates is small, and even if athletes supplement their supply during exercise with sugary drinks or food, prolonged or intense exertion generally incinerates much of the body’s available carbohydrates. Consequently, some experts suggest that athletic success may depend in part on making the body better able to use fat as a fuel. Even the leanest athlete’s body is girded with the stuff. Low-carbohydrate diets will force the body to turn to fat. But working muscles must become used to burning fat, a process that can make exercising on a low-carb diet difficult in the short term. Indeed, athletes on extremely low-carbohydrate diets tend to struggle to finish hard workouts. So researchers at the French National Institute of Sport, Expertise and Performance in Paris and other institutions began to wonder about the possibilities of modified forms of low-carb diets, and specifically about what scientists call “sleeping low.” With a “sleep-low” sports diet, an athlete skips carbohydrates at dinner. In the morning, his or her body should have low reserves of the macronutrient, and any ensuing workouts would force the body to turn to fat, its most abundant fuel. The authors of the new study, in Medicine & Science in Sports & Exercise, suspected that the sleep-low diet needed to be integrated into a broader training plan to show desirable results. They recruited 21 experienced, competitive triathletes. Half were randomly assigned to eat a standard sports diet, with large helpings of carbohydrates at every meal and after workouts. The others consumed the same amount of carbohydrates over the course of the day as the other group, but in a different sequence. Virtually all of their carbohydrates were consumed at breakfast and lunch. At the same time, all of the athletes also began a new training program. In the afternoon, both groups completed a draining, intense interval-training session, designed to increase fitness and deplete the body’s carbohydrate stores. The members of the control group then replenished their carbohydrates at dinner; the sleep-low group did not. The next morning, before breakfast, the volunteers pedaled for an hour at a moderate pace on stationary bicycles. By this time, the sleep-low group was running on carbohydrate fumes and body fat. Afterward, all of the athletes sat down to large, carb-rich breakfasts and lunches, meaning that both groups were flush with carbohydrates for the afternoon interval training. After three weeks, the athletes in the sleep-low group were grumbling about nighttime hunger. But when the researchers now repeated the simulated triathlon, those athletes in the sleep-low group showed notable improvement. Their times on the 10-kilometer running leg at the end of the race were faster by about 75 seconds, or 3 percent, than at the start of the study. The control group had not improved. The sleep-low volunteers also had lost body fat; the other athletes had not. Authors: low carb diet - Google News

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