Evidence explainerCollagen peptidesWhey protein (and other protein powders)
Does Collagen Count as Protein? It Helps With Training, but Whey Builds More Muscle
Collagen peptides are protein, but low in leucine. With resistance training they add modest fat-free mass; against whey in a head-to-head trial, they built less muscle size.
Key takeaways
- Across 19 studies (768 people) with long-term training, collagen peptides increased fat-free mass (SMD 0.48, moderate certainty) and strength (SMD 0.19, low certainty) [1].
- 35 g of collagen peptides supplied 1.0 g of leucine versus 3.0 g in 35 g of whey [2].
- In a 10-week trial, whey increased thigh muscle thickness more than leucine-matched collagen (8.4% vs 5.6%), with similar strength gains [2].
- In 97 untrained middle-aged men who completed a 12-week program, 15 g/day of collagen peptides with training increased fat-free mass more than placebo [3].
- In that trial, the exploratory whey group did not differ significantly from collagen or placebo [3].
Safety at a glance
From our Collagen peptides monograph. Published interactions and cautions only, each with its source.
Who should be careful
- As a main protein source. Collagen is low in leucine; in a 10-week training trial, whey increased muscle thickness more than leucine-matched collagen peptides.[8]
- Before you start. Talk to your pharmacist or clinician before adding this supplement, especially if you take prescription medicines, are pregnant or breastfeeding, or have a chronic health condition.[1]
The evidence, graded
Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.
- Grade BImprovedFat-free mass, muscle and strength with resistance trainingCollagen peptides increased fat-free mass (SMD 0.48, moderate certainty), muscle architecture (SMD 0.39) and maximal strength (SMD 0.19, low certainty) compared with control groups.
Collagen with training: modest gains
A 2024 meta-analysis of 19 studies (768 healthy adults) combining collagen peptides with long-term training found gains in fat-free mass (SMD 0.48), muscle architecture (SMD 0.39) and maximal strength (SMD 0.19) versus control [1]. Certainty was moderate for body composition and low for the rest [1].
In a 12-week trial of 53 older men with sarcopenia, 15 g/day of collagen peptides with resistance training raised fat-free mass more than a silica placebo (4.2 vs 2.9 kg) [4].
Head to head with whey
A 2022 trial randomized 22 untrained young adults to 35 g of whey (3.0 g leucine) or 35 g of collagen peptides with 2.0 g of added free leucine during a 10-week resistance program [2]. Whey increased vastus lateralis thickness 8.4% versus 5.6% and biceps thickness 10.1% versus 6.0%, while strength and power rose similarly [2].
In a 2021 trial, 97 untrained middle-aged men completed 12 weeks of resistance training on 15 g/day of collagen peptides, placebo or whey [3]. Collagen beat placebo for fat-free mass gain (3.42 vs 1.83 kg), while the exploratory comparison found no significant difference between whey and collagen [3].
How to read it
Collagen peptides add protein and showed benefits alongside training, but in the one leucine-matched head-to-head trial, whey built more muscle size [1][2]. For daily protein targets, see how much protein to build muscle.
Quick answers
Does collagen have protein?
Yes. Collagen peptides are protein, but 35 g supplied 1.0 g of leucine compared with 3.0 g in the same amount of whey [2].
How much collagen did the training trials use?
The individual trials we reviewed used 15 g/day for 12 weeks or 35 g/day for 10 weeks [3][2].
Can collagen replace whey?
In the leucine-matched trial, whey increased muscle thickness more, though strength gains were similar [2].
Keep reading
Full monographs
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References
- [1]Impact of Collagen Peptide Supplementation in Combination with Long-Term Physical Training on Strength, Musculotendinous Remodeling, Functional Recovery, and Body Composition in Healthy Adults: A Systematic Review with Meta-analysis. Sports Med, 2024.
- [2]Whey Protein Supplementation Is Superior to Leucine-Matched Collagen Peptides to Increase Muscle Thickness During a 10-Week Resistance Training Program in Untrained Young Adults. Int J Sport Nutr Exerc Metab, 2022.
- [3]The Influence of Specific Bioactive Collagen Peptides on Body Composition and Muscle Strength in Middle-Aged, Untrained Men: A Randomized Controlled Trial. Int J Environ Res Public Health, 2021.
- [4]Collagen peptide supplementation in combination with resistance training improves body composition and increases muscle strength in elderly sarcopenic men: a randomised controlled trial. Br J Nutr, 2015.