Weight loss is helpful for lowering your disease risk, but if you go about it the wrong way, you may end up with a higher body fat percentage than when you started. This is because people often lose muscle as well as fat, with the exact amount depending on a number of factors, such as whether you included exercise in your weight-loss plan and how much protein you consumed on your diet.
Body Composition and Weight Loss
If you try to lose weight by dieting alone, about one-fourth of what you lose will come from muscle instead of fat, according to the American Council on Exercise. Should you then gain back a small amount of weight, this will all be in the form of fat, leaving you with a higher body fat percentage than before you started trying to lose. Making diet and exercise changes can limit this muscle loss, however.
Limiting Muscle Loss With Resistance Training
Adding resistance-training workouts to your routine while you're trying to lose weight will limit muscle loss and ensure a higher percentage of the weight you lose will come from fat. Adults should try to fit in at least two resistance-training sessions per week, including eight to 12 repetitions of 10 to 12 exercises that focus on different major muscle groups, such as the chest, back, abdominals, legs and arms. As you get stronger, increase the weight you use to continue building muscle. Avoid doing your resistance-training workouts two days in a row, however, as this doesn't give your muscles enough time to recover between workouts. The added muscle will also help improve your weight-loss results because muscle takes more calories to maintain than fat.
Importance of Protein Consumption During Weight Loss
Following a high-protein diet has an additive effect: increasing weight loss and improvements in body composition brought on due to exercise, according to a study published in The Journal of Nutrition in 2005. A diet that has a lower ratio of carbs to protein is better for improving body composition during weight loss, according to a study published in The Journal of Nutrition in 2003. People in the higher protein group lost more weight and more fat than those in the lower protein group. Another study, published in the Journal of the American Dietetic Association in 2008, found that people who ate more protein during a diet lost less muscle mass than those who ate less protein.
Preventing Body Fat Gain
A study published in Archives of Internal Medicine in 2004 looked at people who weren't dieting and found those who didn't exercise gained weight and those who exercised lost more weight and body fat as they increased the amount and intensity of their exercise during the week. Thus, once you lose weight you may want to continue exercising to maintain any beneficial body composition changes you've achieved through weight loss. For the most benefits, get at least 300 minutes of moderate-intensity cardio or at least 150 minutes of vigorous cardio per week.
Getting at least 18 percent of your calories from protein may help limit weight regain, notes a study published in the International Journal of Obesity in 2004. This would be about 68 grams per day for those on a 1,500-calorie diet or 81 grams of protein if you eat 1,800 calories per day. Remember that as you lose weight, you need fewer calories, so you can't go back to eating the same amount you did before you lost the weight or you'll gain weight in the form of fat.
- American Council on Exercise: What Are the Guidelines for Percentage of Body Fat Loss?
- Journal of Nutrition: A Reduced Ratio of Dietary Carbohydrate to Protein Improves Body Composition and Blood Lipid Profiles During Weight Loss in Adult Women
- Archives of Internal Medicine: Effects of the Amount of Exercise on Body Weight, Body Composition, and Measures of Central Obesity
- Journal of the American Dietetic Association: Lean Mass Loss Is Associated With Low Protein Intake During Dietary-Induced Weight Loss in Postmenopausal Women
- Journal of Nutrition: Dietary Protein and Exercise Have Additive Effects on Body Composition During Weight Loss in Adult Women
- International Journal of Obesity: High Protein Intake Sustains Weight Maintenance After Body Weight Loss in Humans
- WomensHealth.gov: Physical Activity (Exercise) Fact Sheet