Appetite and Fullness
Eating more protein may help suppress your hunger and appetite for hours after eating.
Protein increases production of hormones like PYY and GLP-1, both of which help you feel full and satisfied. In addition, it helps reduce levels of ghrelin, also known as the “hunger hormone” (2Trusted Source, 3, 4Trusted Source, 5Trusted Source, 6Trusted Source).
In a controlled study of 12 healthy women, the group that consumed a high-protein diet experienced higher GLP-1 levels, greater feelings of fullness and less hunger than the group that ate a lower-protein diet (6Trusted Source).
Due to these effects on appetite and fullness, a higher protein intake typically leads to a natural reduction in food intake.
In another study, when 19 healthy young adults were allowed to eat as much as they wanted on a diet consisting of 30% protein, they consumed an average of 441 fewer calories per day than when they followed a diet consisting of 10% protein (7Trusted Source).
Interestingly, another reason protein is so satisfying seems to be related to the significant increase in metabolic rate that occurs during its digestion (8Trusted Source).
A higher protein intake may increase the number of calories you burn.
Protein digestion appears to boost metabolic rate by an impressive 20–35%, compared to a 5–15% increase for digesting carbs or fat (9Trusted Source).
In fact, several studies have found that when people eat diets high in protein, they end up burning more calories for several hours after eating (8Trusted Source, 10Trusted Source, 11Trusted Source, 12Trusted Source, 13Trusted Source).
In a study of 10 healthy young women, consuming a high-protein diet for one day was shown to increase metabolic rate after meals nearly twice as much as eating a high-carb diet for one day (13Trusted Source).
Weight Loss and Body Composition
Not surprisingly, protein’s ability to suppress appetite, promote fullness and increase metabolism can help you lose weight.
Several high-quality studies have found that increasing protein intake promotes weight and fat loss (14Trusted Source, 15Trusted Source, 16Trusted Source, 17Trusted Source, 18Trusted Source).
In a six-month diet study including 65 overweight and obese women, the high-protein group lost an average of 43% more fat than the high-carb group. What’s more, 35% of women in the high-protein group lost at least 22 pounds (10 kg) (16Trusted Source).
Typically, when you reduce your calorie intake, your metabolism slows down. This is partly due to muscle loss.
However, research suggests that a higher protein intake can help protect against muscle loss and keep your metabolic rate up (15Trusted Source, 17Trusted Source, 19Trusted Source).
In one large review of 24 studies that included over 1,000 people, high-protein diets were found to be more effective than standard-protein diets for losing weight, preserving muscle mass and preventing metabolic slowdown during weight loss (15Trusted Source).
Importantly, standard or high-protein diets can be effective for everyone.
But interestingly, one European study concluded that based on different gene types, high-protein diets would be especially effective for weight loss and maintenance in 67% of the population (14Trusted Source).
SUMMARY:The ability of high-protein diets to decrease hunger, increase feelings of fullness, boost metabolic rate and protect muscle makes them effective for losing weight and improving body composition.