Put down the peanut butter toast. Working out before breakfast burns twice as much fat as eating first, research suggests. Here’s what happens: Eating carbohydrates causes blood glucose levels to rise, which triggers a release of the hormone insulin. Work out after eating and the body uses the sugar to power your muscles. But exercising in a fasted state forces the body to pull energy from fat instead, explains Javier Gonzalez, a physiologist at the University of Bath in the U.K.
His study, published in The Journal of Clinical Endocrinology & Metabolism, compared one group of overweight men that ate before exercise to one that noshed afterward. While there were no weight changes between the groups—the study only lasted six weeks—the lower insulin levels in the exercise-first group meant that they were burning more fat. Twice as much as the breakfast-first group.
If you’re accustomed to eating first thing, wean yourself off the habit slowly, or have a low-carb breakfast. And when you do eat, maybe skip the buttermilk pancakes and breakfast cereal. Try a lean, strong breakfast, or maybe one rich in amino acids that will help to continue your muscle gains after you exercise. Or make it a protein-rich diet to reduce your cravings for the rest of the day, so you can wake up and do the whole thing again tomorrow.