Eating a diet high in protein leads to more muscle gains and body fat losses when combined with regular high-intensity exercise, a new study suggests.
Top protein researchers found that during weight loss, a diet containing a little over 1 gram of protein per pound of body weight was more effective than a diet containing half that amount to promote increases in lean body mass and increased losses of fat mass in combination with high-intensity interval training (1).
In the study, subjects in the high-protein group averaged an increase of 2.64 pounds of lean body mass compared with the control group gaining an average of 0.22 pounds. The higher-protein group also had greater fat loss compared to the control group at 10.56 versus 7.7 pounds, respectively.
Their four-week, single-blinded study randomized 40 overweight young men to two calorie-restricted groups that either ate a lower-protein diet (1.2 grams per kilogram) or a higher-protein diet (2.4 grams per kilogram). All subjects performed resistance exercise training combined with high-intensity interval training for six days per week.
The research suggests the combination of higher protein and high-intensity training can be instrumental for keeping or building muscle during weight loss. Weight-loss diets otherwise often result in a 20 to 30 percent loss of weight coming from muscle mass (2).
The authors of the new research wanted to conduct a proof-of-principle trial to examine whether protein intake during a large calorie reduction with intense exercise would affect body composition. To help get the proper amount of protein, both groups received whey-based protein shakes that were consumed multiple times throughout the day.
The researchers also asked that subjects consume the shakes right after training on exercise days to assist with optimal recovery.
Because the high-protein group needed to consume more than twice the amount of total protein compared to the control group, they had three times the amount of whey protein in their shakes. In fact, the average dietary intake daily for the high-protein group was 245 grams of protein, 311 grams of carbohydrates, and 38 grams of fat. In comparison, the control group on average had 116 grams of protein, 286 grams of carbohydrates, and 86 grams of fat.
Because carbohydrates are an important fuel source during intense exercise, the researchers also sought to increase fat intake for the control group to keep calories similar between groups. The strength of the study is evidenced by provision of all meals and beverages that were consumed over the four-week period.
- Longland TM, Oikawa SY, Mitchell CJ, Devries MC & Phillips SM. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr. 2016 Mar;103(3):738-46.
- Weinheimer EM, Sands LP & Campbell WW. A systematic review of the separate and combined effects of energy restriction and exercise on fat-free mass in middle-aged and older adults: implications for sarcopenic obesity. Nutr Rev. 2010 Jul; 68(7):375-88.