Is it true that working out on an empty stomach helps you burn more fat? The answer is partly yes, but the bigger factor for fat loss is creating an energy deficit.

Javier Gonzalez, a professor of nutrition and metabolism at the University of Bath, explains: "When we exercise, we burn a mix of fuels, mainly carbohydrates and fat. After an overnight fast, the body usually burns slightly more fat and less carbohydrate than if you had eaten breakfast, especially one high in carbs."

However, this does not mean fasted workouts are more effective for losing weight.

"We can only store a limited amount of carbohydrate as glycogen in muscles and the liver, and any extra energy—whether from carbs, fat, or protein—gets stored as body fat.

Therefore, losing fat depends on burning more energy than you consume, not whether you exercise fasted or fed," says Gonzalez.

Fasted exercise may still offer health benefits. Research shows that muscles in a fasted state can move glucose more efficiently out of the bloodstream, which improves blood sugar control.

Gonzalez notes that this effect is especially helpful after meals, and is most noticeable with endurance exercises like jogging or cycling. During high-intensity activities, such as sprinting, the body relies heavily on carbohydrates regardless of fasting. Overall, the benefits of fasted training are modest.

"The main thing is to exercise regularly. Whether you do it fasted or after eating is secondary," Gonzalez emphasizes. Beginners should start with short sessions of 15–20 minutes and gradually increase the duration. "If you feel dizzy or light-headed, that is your body signaling you to stop and eat something."