Does Your Body Burn Muscle Before Fat?

Most people would like to burn as much fat as they can while losing minimal amounts of muscle, or lean body mass. Different weight-loss methods will lead to either more or less muscle being burned by your body, affecting the ultimate body composition that you will end up with once you have lost the weight you are trying to lose.

The faster you lose weight, the more likely you are to be losing mostly water and muscle, rather than fat. According to the Centers for Disease Control and Prevention, you are more likely to maintain your weight loss long term if you lose it at a healthy pace — 1 to 2 pounds per week. This means you don't want to cut too many calories or exercise excessively. It is better to lose the weight gradually over time.

It is common for people to want to just cut calories when they lose weight. Exercise takes a lot of time and effort, and many people would like to avoid exercise. However, if you don't exercise, you will lose muscle as well as fat, especially if you eat too few calories or try to lose weight too quickly. According to a study published in April 2015 by Obesity Review, adding exercise to the mix can help maintain fat-free mass while dieting.

Most experts recommend a combination of diet and exercise in order to lose weight. Not only is cardio exercise recommended to help burn calories more quickly, resistance training or weightlifting is recommended as well, in order to build muscle mass and help prevent the loss of muscle along with fat. According to the Office of Disease Prevention and Health Promotion, adults should get at least 150 to 300 minutes of moderate-intensity exercise and at least two days of resistance training every week.

Those who do cardio training will lose less muscle than those who diet alone as long as the total calorie loss is equal. However, those who add resistance training as well will conserve the most muscle. It takes more calories to maintain muscle than fat, so you also burn more calories at rest when you have more muscle.

Read more: Can Cardio Boost Metabolism?

As you exercise, your muscles' main fuel is composed of glucose and fat. Glucose is provided by the carbohydrates in your diet. When you exercise, the muscles pull the glucose from your bloodstream and use the stored energy in your fat cells. Lower intensity exercise actually uses more of the fat stores, and as your activity level increases in intensity, your muscles pull more glucose from the bloodstream and less fat from your fat cells.

Read more: Which Burns First, Fat or Muscle?

Many people think that they have to exercise at a certain intensity during their cardio training in order to burn fat. According to a review of 18 current research articles, published in May 2017 by Obesity Science & Practice, some studies exist that demonstrate high intensity interval training (HIIT) might be superior to continuous exercise at a low to moderate level for overall fat loss. However, other studies have shown no difference between the two types of exercise.