Protein helps with weight loss by making you feel full longer, burning more calories to digest, and preserving muscle while you eat fewer calories.
How protein helps
- Satiety: protein raises fullness hormones such as GLP-1 and PYY and lowers ghrelin.
- Thermic effect: about 20% to 30% of protein calories are burned digesting it, vs 5% to 10% for carbs and 0% to 3% for fat.
- Muscle: it protects lean mass while you lose fat.
How much
The RDA is 0.8 g per kg of body weight. Many studies on weight loss use 1.2 to 1.6 g per kg.
Good sources
Eggs, chicken, fish, Greek yogurt, beans and tofu.
Caution
People with kidney disease should check with a doctor first.
Satiety hormones
Protein raises levels of satiety hormones such as peptide YY, GLP-1 and cholecystokinin, and lowers ghrelin, the hunger hormone. A diet with 25% to 30% of calories from protein has been shown in studies to reduce appetite and cravings.
Thermic effect of food
Digesting protein burns about 20% to 30% of its calories, compared with 5% to 10% for carbohydrates and 0% to 3% for fat. This adds up to a small increase in daily energy use.
Muscle preservation
During weight loss, a higher protein intake of 1.2 to 1.6 grams per kilogram of body weight, combined with resistance training, helps keep lean mass so more of the weight lost is fat.
Evidence
A meta-analysis of randomized trials in the American Journal of Clinical Nutrition found that higher protein diets lead to modestly greater weight loss and fat loss than standard protein diets. A 2012 trial in the Journal of Nutrition showed increased fullness with high protein breakfasts.
Recommended amounts
The Recommended Dietary Allowance is 0.8 grams per kilogram of body weight per day for healthy adults. For weight loss and active people, evidence supports 1.2 to 2.0 grams per kilogram. A 70 kilogram person would aim for roughly 85 to 140 grams a day.
Distribution
Spread protein across meals, about 25 to 30 grams per meal, to support muscle protein synthesis.
Protein content of foods
- 3 ounces chicken breast: about 26 grams.
- 1 cup Greek yogurt: 17 to 20 grams.
- 1 large egg: 6 grams.
- 1 cup lentils, cooked: 18 grams.
- 3 ounces salmon: about 22 grams.
- 1/2 cup cottage cheese: 12 to 14 grams.
Cautions
People with kidney disease should consult a clinician before raising protein. Processed protein bars may add sugar and calories. Total calories still determine weight change.
How protein affects appetite and metabolism
Protein increases the release of satiety hormones such as GLP-1 and peptide YY and reduces ghrelin, the hunger hormone, so people often feel full longer. The thermic effect of food, the energy used to digest it, is about 20 to 30 percent of calories for protein, compared with 5 to 10 percent for carbohydrates and 0 to 3 percent for fat. Higher protein intake during weight loss helps preserve lean muscle, which keeps resting metabolism higher. Studies on high protein diets show modest additional weight loss compared with lower protein diets.
Amounts and food sources
The recommended dietary allowance is 0.8 grams per kilogram of body weight, but many experts suggest 1.2 to 1.6 grams per kilogram during weight loss. Spreading intake as 25 to 30 grams per meal may help. A 3 ounce cooked chicken breast has about 26 grams, a large egg 6 grams, 6 ounces of Greek yogurt about 17 grams, a cup of cooked lentils 18 grams and a cup of cottage cheese about 25 grams. People with kidney disease should talk to a doctor before increasing protein. Total calories still determine weight change, so protein is one tool within a balanced diet.
Based on data from the NIH and the Academy of Nutrition and Dietetics
