The mother of all questions, the holy grail of quests, the great conundrum: Can you lose fat and build muscle at the same time? SCIENCE says yes! And the answer is protein.
The 4-week research study included 40 overweight young men and put them on a strict diet and exercise program. All subjects had their calories restricted 40% below their maintenance levels. They also adhered to an exercise regimen consisting of weight training and HIIT (high intensity interval training) for 6 days per week.
So, even though all subjects had their calories cut at the same amount, half the subjects were fed low protein (1.2 gram per kilogram per day) and the other half were fed high protein (2.4 grams).
Both groups lost fat. No surprise there. But the higher protein group lost more fat, 10.5 pounds, compared to the lower protein group, who lost an average of 8 pounds. Pretty significant since we're only talking about 4 weeks here. That would be 15 pounds more fat loss over 6 months.
And now it gets really interesting. The group that got to eat more protein built some muscle during the study (about 2.5 pounds). The lower protein group didn't lose any muscle, but didn't add any either.
You can LOSE fat and Keep your muscle :
All calories are not created equal. Both groups ate the same amount of calories. Exercised the same. Yet the high protein group lost more fat and gained muscle. This shows consuming approximately 1 g / lb of Lean Body Mass will not only protect against muscle mass loss during calorie restriction, and will also add some muscle.
How you train while you cut matters:
Weight training will help you keep your gains. Even though the low protein group didn’t lose as much fat or gain any muscle, they did retain muscle.
Thomas M Longland, Sara Y Oikawa, Cameron J Mitchell, Michaela C Devries, and Stuart M Phillips. 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. American Journal of Clinical Nutrition, January 2016.