Protein Supplements: Do they work for trained people?

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Protein Supplements: Do they work for trained/experienced individuals doing resistance training?

George Cho, MFSc, CEP, , EIM-2, ND


Pasiakos and colleagues wrote a 2015 review of the literature regarding protein supplementation. Below is a summary of their review on how protein effects body composition changes and performance measures in individuals who are experienced in resistance training (they are not beginners). A link to the full text is available below.


Protein Supplementation during Over-training

Fry et al found no effects of protein supplementation during 1 week of high volume training. However, both parties were consuming high protein diets (2.4 g/kg and 2,2g/kg for protein and control groups, respectively. Ratamess et al and Kraemer also investigated protein supplementation during over-training. A 4 week,  high volume (10-12 reps) training period wasfollowed by 2 weeks of low volume training (3-5 reps). Protein supplementation attenuated initial declines in strength and power after week 1 but during the later stages and into the 2 week low volume period, the control grouphad higher bench press strength vs the protein supplement group.


Protein vs Isocaloric Carbohydrate

A 6 week high volume / high resistance, 3 training days + 1 rest day training program, the effects of whey and carbohydrate was studied. Lean mass changed greater for the protein supplement group but bench press and leg squat strength increased similarly for both groups.

Cribb et al compared a whey protein supplement to carbohydrate supplementation during 11 weeks of resistance training. Lean mass increased in both groups but strength improved greater in the protein group. The sample size was small for this study with only 5 participants.


Protein vs Protein and Carbohydrate

Cribb et al compared protein (0.6g/kg) with protein + carbohydrate (1.3g/kg)  supplementation. Lean mass increased similarly as did fiber-type cross sectional area. The reviewers commented: "... the reports by Cribb et al. suggest that protein not carbohydrate provides the stimulus for muscle fiber hypertrophy during resistance training. These data also suggest that daily protein supplementation above 0.6 g/kg may not be necessary, especially when mean daily intake of dietary protein without supplementation was already at or above 1.6g/kg." (p. 120)


Protein source and combinations

One study showed that whey protein resulted in greater improvement in lean body mass and decreased fat mass with greater strength gains compared to casein after a 10 week training program. However, female athletes in a 8 week,  4 days-a-week whole body resistance training program found similar benefits in lean mass, strength and power regardless of the protein type.  

When comparing rice and whey protein, there was no difference found after an 8-week resistance training program for lean mass and improvements in strength and power. 

When researchers compared whey + casein vs whey + glutamine + branch chain amino acids vs carbohydrates, the whey + casein group had greater improvements in lean mass, but ALL groups were equal when comparing improvements in bench press and leg press strength. However, in this study, dietary energy and protein intakes varied between groups. "Thus, the effects of protein supplementation versus overall dietary protein intake could not be determined." (p. 121).


Protein Timing

A study compared protein supplementation in the evening, morningor before and after workouts. Supplementation occurred four times a week for 10 weeks. Supplements were given on non-training days too. The researchers found no difference in strength and power. They point out that the lack of differences may be due to the fact that the athletes consumed high daily dietary protein (> 1.6 g/kg).


Conclusions on Protein Supplementation for Resistance-trained Individuals

"Protein supplements had little or no effect on measures of strength and body composition when programs were 4 weeks or less, whereas positive effects of protein supplements have been observed on changes in lean mass and/or muscle strength when training programs were 8 weeks or longer. The addition of carbohydrate to protein does not appear advantageous, whereas the addition of casein or BCAA to whey protein may lead to greater gains in lean mass and strength, but there may be a ceiling to the beneficial effect from the additional source of protein" (p. 121, 123)


CFEMC Comment

It is our opinion that this review does not definitively confirm that protein supplements may work for every trained individual. There is conflicting evidence which warrants more research. Our recommendation to individuals is to ensure an adequate, varied daily protein intake alongside a healthy and nutrition diet,  and then consider experimenting with supplementation to see if it is helping the individual. Please read our other review on the subject in the nutrition section of this website for another summary of an excellent review paper from the year 2016.



Pasiakos, SM., McLellan T., Lieberman, H. The effects of protein supplements on muscle mass, strength, and aerobic and anaerobic power in healthy adults: A systematic review. Sports Med (2015) 45:111-131

Click here for the Full Text of the Review

George Cho