Whey protein and muscle gains from resistance exercise
What it found
In 32 men doing four weeks of supervised resistance exercise, those taking whey protein isolate gained more muscle mass and showed greater strength and endurance in some knee and shoulder muscles than those taking a placebo.
Both groups ate controlled meals provided by the researchers.
What they found
Studies in people
Muscle mass
The whey protein group showed a significant increase in muscle mass after four weeks, while the placebo group did not. There was a significant interaction between the groups for muscle mass increase.
Muscle strength
The whey protein group showed significantly increased peak torque in the dominant knee flexors, dominant shoulder extensors, and non-dominant shoulder extensors. The placebo group showed no significant changes in these measures.
Muscle endurance
The whey protein group showed significantly increased total work in the dominant knee extensors and dominant shoulder extensors. The placebo group showed no significant changes in these measures.
Body composition
Both groups showed significant decreases in body weight, body fat, and body fat percentage, with no significant differences between the groups.
Calorie intake
Actual calorie intake was significantly lower than estimated in both groups, by 108.4 kcal per day in the whey protein group and 127.8 kcal per day in the placebo group. There was no difference between the groups in this shortfall.
What the authors conclude
“These results suggest that whey protein supplementation enhances resistance exercise-induced increase in muscle mass and overall muscular strength and endurance, independent of dietary influence.”
Also in their conclusions
- They conclude that whey protein supplementation promotes muscle mass increase and selective increases in muscular strength and endurance from resistance exercise.
- They suggest that whey protein supplementation is practically effective independently of the normal diet.
How it was done
The authors note that studies on whey protein and resistance exercise have given inconsistent results, possibly because people's normal diets were not well controlled. They wanted to test whey protein while directly providing all meals, rather than relying on food diaries.
Thirty-two men in their 20s and 30s were randomly assigned to take either a whey protein isolate supplement or a carbohydrate placebo three times a day for four weeks. All participants were given three meals a day matched to their estimated daily calorie needs and did supervised resistance exercise for 60 minutes a day, six days a week.
What it can’t tell you
- This was a four-week study in young men doing a specific exercise program, so the results may not apply to other groups or longer periods.
- The study cannot show whether whey protein would have the same effects without the supervised exercise and controlled meals.
Who paid
- Funding
- Funded by Maeil Health Nutrition Co., Ltd. (from the PubMed record).
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- Pusan National University, Republic of Korea
The paper
- Title
- Effects of Whey Protein Supplement on 4-Week Resistance Exercise-Induced Improvements in Muscle Mass and Isokinetic Muscular Function under Dietary Control
- Type
- Randomised controlled trial
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Kim CB, Park JH, Park HS, Kim HJ, Park JJ (2023). Effects of Whey Protein Supplement on 4-Week Resistance Exercise-Induced Improvements in Muscle Mass and Isokinetic Muscular Function under Dietary Control. Nutrients. doi:10.3390/nu15041003Free full textPubMed 36839361DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error