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.
Speed of Weight Loss
The faster you lose weight, the more likely you are to be losing mostly water and muscle, rather than fat. According to the American Family Physician, aim to lose no more than 2 pounds. per week if you don't want to lose too much muscle mass. 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 go on a very low-calorie diet or try to lose weight too quickly. According to the National Council on Strength and Fitness, or NCSF, those who fast or skip meals start to lose mainly lean muscle tissue.
Dieting Plus Exercise
Most experts, including the NCSF, recommend a combination of diet and exercise in order to lose weight. Not only is cardio exercise recommend to help burn calories more quickly, resistance training is recommend as well in order to build muscle mass and help to keep from losing muscle along with fat. 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.
Fueling Your Muscles
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.
Many people think that they have to exercise at a certain intensity during their cardio training in order to burn fat. However, a study published in the "American Journal of Clinical Nutrition" showed that both high-intensity and low-intensity exercise result in the same percentages of fat loss and muscle loss, in this case 16 percent and 10 percent, respectively. Keep in mind that this was cardio exercise without added resistance training, which would help to lessen the loss of muscle even further.
The best way to lose the maximum amount of fat while conserving as much muscle as possible is to use a combination of diet, cardiovascular exercise and resistance training to lose weight at a rate of half a pound to 2 pounds per week, according to the National Council on Strength and Fitness.