Shifting From Carbohydrate to Fat for Exercise

Summary:

The following information was written by Atkins professionals.

The purpose of this study was to assess metabolic adaptations to a high-fat diet in endurance cyclists. Sixteen endurance-trained cyclists were randomly assigned to one of two diet groups for a period of 15 days. One group remained on their habitual diet (30% of calories from fat) while the other group consumed a high-fat diet (69% of calories from fat) of the same caloric value. Results revealed that the level of certain enzymes involved in fat metabolism was elevated, signaling a shift from burning carbohydrate for energy to burning fat for energy. This change in fuel utilization occurred within five days of switching to the high-fat diet. Subjects also used less muscle glycogen (stored carbohydrate) after 15 days of the high-fat diet. The authors concluded that consuming a high-fat diet for as little as five to 10 days significantly alters the body’s fuel selection from carbohydrate to fat without altering cycling performance.

Commentary:

The following information was written by Atkins professionals.

The findings of this study can be applied to the Atkins Principle of Good Health. A controlled carbohydrate lifestyle will not impair athletic performance. According to this study, the body adapts to high-fat consumption by burning fat for energy instead of carbohydrate, provided carbohydrate intake is controlled. This adaptation can occur in as few as five days.