There are modest benefits to exercising on an empty stomach, but it’s more important to burn more energy than you’re consuming There are modest benefits to exercising on an empty stomach, but it’s more important to burn more energy than you’re consuming ‘T here’s an element of truth to that,” says Javier Gonzalez, a professor of nutrition and metabolism at the University of Bath. “When we exercise, we’re always burning a mix of fuels – mainly carbohydrates and fat. If you’ve fasted overnight,