According to multiple studies, many of which stemming from the University of South Florida labs run by Jose Antonio, PhD and Bill Campbell, PhD, increasing protein intake results in greater fat loss and improved body composition in resistance trained individuals. This article summarizes some of the studies and relevant conclusions here.
In my n=1 case when I did a high protein experiment without resistance training I added 8 lbs of lean mass and went down to 21% body fat. But you don’t have to take my word for it... there are multiple studies on it! I’ve aggregated them on one page here, as well as the lack of negative effects from high protein intakes in resistance trained athletes with no health conditions. Body composition scientist Dr. Bill Campbell is on the Optimal Protein Podcast Protein Series discussing these topics and more!
Individual protein intakes should be determined on your own or working with a nutritionist or care provider. I have a macro calculator available on the website here to help determine potential approximate intakes depending on goals. It can be found here.
The aforementioned studies and relevant excerpts follow.
Effects of High Versus Low Protein Intake on Body Composition and Maximal Strength in Aspiring Female Physique Athletes Engaging in an 8-Week Resistance Training Program
“Fat-free mass increased significantly more in the HP group as compared with the LP group (p = .009), going from 47.1 ± 4.5 to 49.2 ± 5.4 kg (+2.1 kg) and from 48.1 ± 2.7 to 48.7 ± 2 kg (+0.6 kg) in the HP and LP groups, respectively. Fat mass significantly decreased over time in the HP group (14.1 ± 3.6 to 13.0 ± 3.3 kg; p < .01), but no change was observed in the LP group (13.2 ± 3.7 to 12.5 ± 3.0 kg).”
A high protein diet (3.4 g/kg/d) combined with a heavy resistance training program improves body composition in healthy trained men and women – a follow-up investigation
Jose Antonio, PhD et al.
“the HP group experienced a greater decrease in fat mass and % body fat. Conclusion:
Consuming a high protein diet (3.4 g/kg/d) in conjunction with a heavy resistance-training program may confer benefits with regards to body composition. Furthermore, there is no evidence that consuming a high protein diet has any deleterious effects.”
The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals.
Jose Antonio, PhD et al.
Consuming 5.5 times the recommended daily allowance of protein has no effect on body composition in resistance-trained individuals who otherwise maintain the same training regimen. This is the first interventional study to demonstrate that consuming a hypercaloric high protein diet does not result in an increase in body fat.”
Effects of High vs. Low Protein Intake on Body Composition and Maximal Strength in Aspiring Female Physique Athletes Engaging in an 8-Week Resistance Training Program
February 2018, International Journal of Sport Nutrition and Exercise Metabolism 28(6):1-21
“Fat-free mass (FFM) increased significantly more in the HP group as compared to the LP group (p=0.009), going from 47.1 ± 4.5kg to 49.2 ± 5.4kg (+2.1kg) and from 48.1 ± 2.7kg to 48.7 ± 2 (+0.6kg) in the HP and LP groups, respectively. Fat mass significantly decreased over time in the HP group (14.1 ± 3.6kg to 13.0 ± 3.3kg; p<0.01) but no change was observed in the LP group (13.2 ± 3.7kg to 12.5 ± 3.0kg). While maximal strength significantly increased in both groups, there were no differences in strength improvements between the two groups. In aspiring female physique athletes, a higher protein diet is superior to a lower protein diet in terms of increasing FFM in conjunction with a resistance training program.”
High-protein diets in trained individuals
On the lack of deleterious effects on fat mass or organ function from consuming a higher level of protein in resistance trained individuals:
A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males