High-performance athletes and common people can burn more fat and be fitter by cutting carbohydrate intake and eating more fat, according to a New Zealand research out on Monday.
Making athletes adapt to a different diet changed the ability of their muscles to burn different fuels, enabling their bodies to use different fuel sources for different exercise intensities, according to the study from Massey University.
Generally speaking, this means using fat for longer duration, less intense exercise and conserving carbohydrate for shorter, high-intensity bouts, researcher Will O’Connor said in a statement.
Participants in the study were restricted to 2 grams of carbohydrate per kg of body weight per day for four weeks, with an emphasis on eating fat instead, so a typical day might consist of coffee with cream, eggs with bacon, limited fruit, meat and a high volume of vegetables.
They then had a four-hour cycle test where their respiratory exchange ratio—the ratio of oxygen and carbon dioxide inhaled and exhaled—was measured.
O’Connor found that athletes who had been eating a low-carbohydrate, high-fat diet were burning more fat during exercise.
For athletes, this means they were more metabolically efficient, had a greater ability to carry oxygen to their muscles and were able to mentally push through an endurance event because of fuel availability.
“The body can only store so much carbohydrate in the liver or in the muscles. If the body’s relying on carbs during exercise, these stores get used up quickly and that’s when athletes hit the wall,” O’Connor said.
Previous estimates of an athlete’s fat-burning ability had peaked at 1 gram per minute, but his study had measurements of up to 1.97 grams per minute.
“This research shows that changing your diet can totally change how your body runs. You can literally increase your fitness by changing your diet,” he said.
“We also noted drastic changes in body composition or body-fat percentage. When you’re eating a high carbohydrate diet, particularly if you’re eating a lot of sugar, your insulin levels can spike. Insulin causes the body to store fat and also stop it from burning fat while it deals to the sugar. This causes the ‘energy crash’ that people experience and means you’re putting on more fat.”