Do You Burn More Fat if You Work Out Without Eating?

You Should Know: If you’ve ever heard that you burn more fat when you exercise on an empty stomach, that’s not entirely true. As some experts point out, there’s “an element of truth” to that statement, but it’s not exactly accurate. 

Going Deeper: During exercise, the body selectively chooses what fuel to burn based on the intensity and duration of the exercise, as well as whether it’s in a fed or fasted state. When you work out at lower intensities (like zone 2 running) without having eaten, your body utilizes more stored fats as fuel to preserve blood sugar levels. If you eat a carb-heavy meal soon before training, however, your body first utilizes that fuel as it becomes available as blood glucose.    

Takeaway: The idea that you burn more fat while working out fasted isn’t entirely untrue — that can be the case under certain conditions — but it’s a myth by scientific standards. 

Bottom Line: No matter how you fuel (or don’t fuel) your training, if you want to lose body fat, you must burn more calories than you consume. Working out on an empty stomach, particularly endurance exercise, has modest benefits but is splitting hairs as far as fat loss is concerned.