To eat or not to eat before a workout

New York

FOR those who can stomach it, working out before breakfast may be more beneficial for health than eating first, according to a study of meal timing and physical activity. Its results indicate that when we eat affects how much fat we burn during exercise and also alters molecular activity within fat cells, in ways that could have long-term implications for our physical well-being.

Athletes and scientists have long known that meal timing affects performance. Most obviously, if you eat first, you have relatively high levels of blood sugar. Working muscles can readily use this sugar as fuel.

If, on the other hand, you have fasted before working out, your muscles must rely primarily on the body's skimpy supply of stored carbohydrates or its larger reservoirs of fat. Accessing this fat, however, requires extra metabolic steps to become available as energy, which makes it a relatively inefficient fuel source during times of strenuous exercise. As a gen…