If you consume more calories than you expend, you will gain weight. Protein is a source of calories along with carbohydrates and fat, meaning that excess consumption of protein can stop you from losing weight. To evaluate whether or not your protein shakes are putting you over your daily allotment, you first need to know how many calories you should be consuming each day for your body size and weight-loss goals.
Calories from Protein
Each gram of protein contains 4 calories, so a shake with 25 g of protein contains 100 calories from protein in addition to calories from added fruit or sweeteners. If you are drinking a protein shake each day in excess of what your body needs for energy, the extra 100 to 200 calories will add up to 10 to 20 lb. of weight gain each year.
Protein Recommendations by Percent of Calories
Protein recommendations are often listed two different ways: as a percentage of total calories or as a number of grams per kilogram of body weight. Percentage recommendations range between 15 and 30 percent of total calories, depending on the amount of exercise you do and your health condition. For example, endurance athletes require more protein than moderate exercisers, and people with kidney dysfunction must limit their intake of protein.
Protein Recommendations by Body Weight
You will get a more accurate and easily understandable estimate of your protein needs by using the grams per kilogram method. If you are sedentary or a moderate exerciser -- meaning you work out for less than an hour each day -- you will need between 0.8 and 1 g per kilogram of body weight. If you are active in sports or undertaking more serious endurance training, your protein needs will be between 1.2 and 1.8 g per kilogram of body weight. For example, a 150 lb. person needs 55 to 68 g of protein to support a sedentary or moderately active lifestyle or 82 to 123 g of protein to support a training regimen.
Total Caloric Intake
Even if you use the grams per kilogram of body weight method of estimating your protein needs, you still need to make sure that your total caloric intake is not in excess of what you need to meet your weight-loss goals. A quick thumbnail estimate used by dietitians in the absence of metabolic testing equipment is 20 to 25 calories per kilogram per day for weight loss. For example, a 150 lb. person -- whose weight in kilograms is 68 -- needs to reduce their intake to 1,370 to 1,700 calories to lose weight.
References
- "Nancy Clark's Sports Nutrition Guidebook"; Nancy Clark; 2008
- "Krause's Food and Nutrition Therapy: 12th Edition"; L. Kathleen Mahan and Sylvia Escott-Stump; 2008
- "Nutrition and Diagnosis-Related Care: Fifth Edition"; Sylvia Escott-Stump; 2002
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