Intermittent fasting is one of the many modern diet trends that are all the rage. A simple Google search yields thousands of articles by advocates claiming outstanding results. Yes, some results are impressive, but they do not make intermittent fasting a good diet plan for athletes. (Read about the dangers of fad diets.)
Intermittent fasting involves a meal schedule with a specific range of time during which you eat your day's worth of calories, followed by a period of fasting generally lasting between 16 and 36 hours. The fasting increases insulin sensitivity, which leads to more effective fat burning and weight loss.
It recently gained notoriety when studies conducted by Dr. Marc Mattson reported that intermittent fasting increased the lifespan of rodents and promoted improvements in major health markers: insulin sensitivity, body composition and brain capacity.
It does seem like there are practical applications for this strategy, particular for sedentary people. Someone can fast during the day, indulge in a late-night dinner without associated health risks, and actually lose some weight.
However, the picture is different for athletes.
Athletes need fuel to perform, which is why nutritionists recommend eating three main meals and three smaller meals or snacks each day. The goal is to provide a consistent flow of energy to ensure that athletes can give their max during workouts, practices and games. Intermittent fasting's long durations without food can leave an athlete feeling tired and weak, and may even force his or her body to break down muscle to use for energy. (Discover the 5 pillars of sports nutrition.)
In addition, spreading out meals over the day helps prevent stomach issues that can occur from eating a single large meal. The typical performance athlete needs to consume more than 3,000 calories per day. Imagine eating a full Thanksgiving dinner with dessert, every night.
Bottom line: elite performance is achieved with the help of proven nutrition strategies. Tempting diet fads—like intermittent fasting—may promise the world, but more often than not, they are not applicable to athletes. Buying in to intermittent fasting might help you lose a few extra pounds, but your performance will suffer. Is it worth the cost? Most likely, no.
Joseph Goldstein, The New Age Cavemen and the City, http://www.nytimes.com/2010/01/10/fashion/10caveman.html?_r=1
Mattson MP, Wan R. "Beneficial effects of intermittent fasting and caloric restriction on the cardiovascular and cerebrovascular systems." J Nutr Biochem. 2005 Mar; 16(3):129-37.