Can athletes improve their performance by following a diet that is low in carbohydrates and high in fat (LCHF)? Several popular sports magazines have carried articles advocating LCHF diets, even though at present there is no data to support this regimen for sports that require speed, including marathon running and long-distance bicycle racing. LCHF diets can slow you down in both training and racing.
The typical LCHF diet includes lots of meat, chicken, fish and full-fat dairy products, and severely restricts fruits, vegetables, bakery products, pastas, and all foods and drinks with added sugar.
The Flaw in Studies Used to Support LCHF for Athletes
Anything that increases a person’s maximal ability to take in and use oxygen (VO2max) will also help him move faster over distance. One report appears to show increases in off-road cyclists’ maximal ability to take in and use oxygen (VO2max) with a LCHF diet. That would have made them faster, but VO2max depends on a person’s weight and low-carbohydrate diets can help you lose weight. When you correct for the diet-induced weight loss, all the oxygen capacity gains appear to be from the loss of weight and not their ability to take in more oxygen and go faster.
