Your body does burn fat as fuel during lower-intensity workouts (a.k.a. the "fat-burning zone" of about 65 percent of your max)—however that's not necessarily what you need to focus on for weight loss. What counts the most is your overall calorie expenditure, not the fuel source. “The higher the intensity of your workout, the more total calories you will burn," says Marta Montenegro, a certified strength and conditioning coach and adjunct professor of exercise and sports sciences at Florida International University. That burn lasts up to 24 hours after your last rep or step, and studies show you’ll shrink your belly fat faster, she adds.
But before you go switching all of your cardio sessions to high-intensity, maximum-effort training, remember that this type of exercise isn’t without its risks, such as injury and overtraining fatigue. Montenegro recommends alternating between low- and high-intensity workouts to give your body proper time to recover and build consistency. For example, do your high-intensity interval training on Mondays and Thursdays, low- to moderate-intensity on Wednesdays and Saturdays, and mix in some yoga or strength on Tuesdays and Fridays.
