High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations: A Comparison Between Habitual Vegans and Omnivores.
Study Goal
The researchers aimed to compare the effects of an exclusively plant-based protein diet versus a mixed diet on muscle mass and strength gains in young men undergoing resistance training.
Results Summary
Both plant-based and mixed diets resulted in similar significant increases in leg lean mass, muscle cross-sectional area, and strength, with no statistically significant differences between the groups. The study concluded that protein source does not affect resistance training-induced adaptations when protein intake is adequate.
Population
Healthy young men (19 vegans and 19 omnivores, aged 26 ± 5 years).
Effective Dosage
1.6 g kg-1 day-1 of protein, adjusted via supplemental protein (soy for vegans, whey for omnivores).
Duration
12 weeks.
Interactions
None mentioned.
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
exclusively plant-based protein diet | no change | supporting muscle strength and mass accrual | untrained young men consuming adequate amounts of protein | - | is not different than a protein-matched mixed diet | #1 |
resistance training program | increase | leg lean mass | young men who were habitual vegans | 1.2 ± 1.0 kg | significant PRE-to-POST increases | #2 |
resistance training program | increase | rectus femoris cross-sectional area | young men who were habitual vegans | 1.0 ± 0.6 cm2 | significant PRE-to-POST increases | #3 |
resistance training program | increase | vastus lateralis cross-sectional area | young men who were habitual vegans | 2.2 ± 1.1 cm2 | significant PRE-to-POST increases | #4 |
resistance training program | increase | vastus lateralis muscle fiber type I cross-sectional area | young men who were habitual vegans | 741 ± 323 µm2 | significant PRE-to-POST increases | #5 |
resistance training program | increase | vastus lateralis muscle fiber type II cross-sectional area | young men who were habitual vegans | 921 ± 458 µm2 | significant PRE-to-POST increases | #6 |
resistance training program | increase | leg-press 1RM | young men who were habitual vegans | 97 ± 38 kg | significant PRE-to-POST increases | #7 |
resistance training program | increase | leg lean mass | young men who were omnivores | 1.2 ± 0.8 kg | significant PRE-to-POST increases | #8 |
resistance training program | increase | rectus femoris cross-sectional area | young men who were omnivores | 0.9 ± 0.5 cm2 | significant PRE-to-POST increases | #9 |
resistance training program | increase | vastus lateralis cross-sectional area | young men who were omnivores | 2.8 ± 1.0 cm2 | significant PRE-to-POST increases | #10 |
resistance training program | increase | vastus lateralis muscle fiber type I cross-sectional area | young men who were omnivores | 677 ± 617 µm2 | significant PRE-to-POST increases | #11 |
resistance training program | increase | vastus lateralis muscle fiber type II cross-sectional area | young men who were omnivores | 844 ± 638 µm2 | significant PRE-to-POST increases | #12 |
resistance training program | increase | leg-press 1RM | young men who were omnivores | 117 ± 35 kg | significant PRE-to-POST increases | #13 |
dietary protein source | no change | leg lean mass | healthy young men undertaking resistance training | - | no between-group differences | #14 |
dietary protein source | no change | rectus femoris cross-sectional area | healthy young men undertaking resistance training | - | no between-group differences | #15 |
dietary protein source | no change | vastus lateralis cross-sectional area | healthy young men undertaking resistance training | - | no between-group differences | #16 |
dietary protein source | no change | vastus lateralis muscle fiber type I cross-sectional area | healthy young men undertaking resistance training | - | no between-group differences | #17 |
dietary protein source | no change | vastus lateralis muscle fiber type II cross-sectional area | healthy young men undertaking resistance training | - | no between-group differences | #18 |
dietary protein source | no change | leg-press 1RM | healthy young men undertaking resistance training | - | no between-group differences | #19 |
BACKGROUND: Acute protein turnover studies suggest lower anabolic response after ingestion of plant vs. animal proteins. However, the effects of an exclusively plant-based protein diet on resistance training-induced adaptations are under investigation. OBJECTIVE: To investigate the effects of dietary protein source [exclusively plant-based vs. mixed diet] on changes in muscle mass and strength in healthy young men undertaking resistance training. METHODS: Nineteen young men who were habitual vegans (VEG 26 ± 5 years; 72.7 ± 7.1 kg, 22.9 ± 2.3 kg/m2) and nineteen young men who were omnivores (OMN 26 ± 4 years; 73.3 ± 7.8 kg, 23.6 ± 2.3 kg/m2) undertook a 12-week, twice weekly, supervised resistance training program. Habitual protein intake was assessed at baseline and adjusted to 1.6 g kg-1 day-1 via supplemental protein (soy for VEG or whey for OMN). Dietary intake was monitored every four weeks during the intervention. Leg lean mass, whole muscle, and muscle fiber cross-sectional area (CSA), as well as leg-press 1RM were assessed before (PRE) and after the intervention (POST). RESULTS: Both groups showed significant (all p < 0.05) PRE-to-POST increases in leg lean mass (VEG: 1.2 ± 1.0 kg; OMN: 1.2 ± 0.8 kg), rectus femoris CSA (VEG: 1.0 ± 0.6 cm2; OMN: 0.9 ± 0.5 cm2), vastus lateralis CSA (VEG: 2.2 ± 1.1 cm2; OMN: 2.8 ± 1.0 cm2), vastus lateralis muscle fiber type I (VEG: 741 ± 323 µm2; OMN: 677 ± 617 µm2) and type II CSA (VEG: 921 ± 458 µm2; OMN: 844 ± 638 µm2), and leg-press 1RM (VEG: 97 ± 38 kg; OMN: 117 ± 35 kg), with no between-group differences for any of the variables (all p > 0.05). CONCLUSION: A high-protein (~ 1.6 g kg-1 day-1), exclusively plant-based diet (plant-based whole foods + soy protein isolate supplementation) is not different than a protein-matched mixed diet (mixed whole foods + whey protein supplementation) in supporting muscle strength and mass accrual, suggesting that protein source does not affect resistance training-induced adaptations in untrained young men consuming adequate amounts of protein. CLINICAL TRIAL REGISTRATION: NCT03907059. April 8, 2019. Retrospectively registered.