Should You Skip Breakfast to Burn More Fat During a Workout?

An Associated Press article suggesting that, because skipping breakfast before a workout burns more fat, such a practice may be effective for body fat loss. Yet, the study on which the article is based provides absolutely no evidence that such a practice would result in a stable loss of body fat. Sure, if your body is depleted of stored carbohydrates in the form of muscle and liver glycogen, you will burn more fat during exercise. However, a close look at the article reveals that the fat burned is in the muscle, and not around the waist or other parts of the body where people generally want to lose fat. Thus, exercising in a fasted state merely depletes intramuscular fat that is replenished upon eating. So there is no net body fat loss unless one consumes fewer calories than are used, which requires dietary control. So we can’t escape from the truism that the only way to lose weight is to burn more calories than you take in.

The following are additional reasons not to exercise in a fasted state:

• You will feel less energetic and more lethargic
• The quality of your workout will diminish
• Your motivation to exercise will be reduced
• You will cannibalize muscle to convert protein into needed carbohydrates

The only advantage to running in a fasted state might be for long-distance runners who wish to train their bodies to preferentially burn fat, thereby sparing muscle and liver glycogen to avoid “hitting the wall” late in a race. However, training with long-distance runs accomplish the same goal.