Everyone knows that eating excess calories increases body fat, and calories come from carbohydrates, fat, protein or alcohol. But the amounts of these calorie sources matter when it comes to getting fat, losing fat or maintaining a healthy body composition. Note that we did not say “healthy body weight.” That’s because “overweight” is only a problem when you are “over-fat.”

Question: Why is fat loss more important than weight loss?

Answer: When weight is lost, it can come from fat or fat-free mass. Fat-free mass is mainly body protein (primarily muscle) along with a much smaller amount of carbs stored in a form called glycogen. The goal is to lose only fat. However, due to the high water content of muscle, it is easy to lose the wrong kind of weight rapidly when the loss is not coming from fat.

Muscle burns a lot of calories. Any muscle loss reduces the body’s calorie needs, making it more difficult to lose fat or prevent fat gain. When someone loses the wrong kind of body weight (fat-free mass), they are setting themselves up for a long-term losing battle with gaining fat.

Q: What promotes fat loss without muscle loss?

A: Meeting protein needs, combined with adequate calories, helps to prevent muscle loss. Also, exercise, especially strength training, helps the body hold on to muscle and even gain muscle if calories and protein are adequate in the diet.

Having more muscle means the body uses more calories, even at rest, because it takes a lot of calories just to maintain muscle tissue. In addition to helping maintain muscle, it is well known that high-protein foods satisfy the appetite better than foods high in carbs, fat or alcohol.

Q: How much protein do you need during fat loss?

A: Most research indicates that protein in the diet needs to increase and may need to double to prevent muscle loss during dieting. The usual recommendation for protein is just under 0.4 grams of protein for each pound of body weight. Assuming you have good healthy kidneys, calories from protein should be increased to provide as much as 0.8 grams of protein per pound of body weight. Protein recommendations are based on body weight, so heavier people need more protein. During dieting, calories should be cut by reducing carbs, fat and/or alcohol.

Q: Is cutting carbs important during fat loss?

A: To some extent, but remember that the brain alone uses about 500 calories worth of blood sugar every day. So, most people function better with some carbs in their diet. The amount and types of physical activity a person does also affect carb needs. The carbs stored in muscle (glycogen) are needed for moderate to high-intensity exercise. So, the amount of carbohydrates that makes sense in the diet is highly dependent on the amount and intensity of physical activity. If someone has no significant exercise or participates only in low-intensity exercise, limiting carbs can make sense. Also, remember that both fat and alcohol are high in calories and can be easily over-consumed.

Q: What foods are good protein sources?

A: Key foods with high-quality protein include fish, poultry, lean meats, eggs and milk products. Beans, nuts and grains have lower protein quality and contain three to four times more calories from carbs and/or fat along with their protein. To satisfy appetite, prevent muscle loss and keep calorie needs higher, focus on protein.

Alan Titchenal, Ph.D., C.N.S., and Joannie Dobbs, Ph.D., C.N.S., are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa. Dobbs also works with University Health Services.