No Differences in Muscle Gains Between Trained Vegetarian and Non-Vegetarian Women
Baffling.
If you thought going vegan meant losing out on significant muscle gains, a 2026 study published in the Scandinavian Journal of Medicine & Science in Sports has some news for you. Researchers put strict vegetarian and non-vegetarian women through the same 16-week resistance training program without any protein supplementation, and both groups showed nearly identical muscle size and strength gains, even though the vegetarians ate significantly less protein throughout. So, while consuming mostly animal protein is certainly an effective path towards meaningful hypertrophy, this study suggests that for previously untrained women, what matters most may be showing up and lifting, not so much what's on the dinner plate.
Aim
To compare muscular and body composition adaptations between young strict vegetarian (VEG) and non-vegetarian (NV) untrained women following a 16-week resistance training program, without the use of protein or amino acid supplementation. The researchers specifically wanted to know whether real-world dietary differences, rather than laboratory-controlled protein doses, would produce measurable differences in hypertrophy and strength.
Methods
This was a non-randomised controlled trial recruiting women aged 20 to 40 years who had been untrained for at least six months and had followed their respective diets (strictly vegetarian or non-vegetarian) for a minimum of six months before enrolment. The final sample included 25 VEG participants (average age 28.7 years) and 20 NV participants (average age 30.9 years), all of whom trained twice per week on non-consecutive days.
Both groups completed the same full-body resistance training program based on a linear periodisation model. Sessions included 11 exercises targeting all major muscle groups, progressing from 2 sets of 12–15 reps in the opening weeks to 4 sets of 6–8 reps in the final block. All sessions were directly supervised, and training volume-load was recorded at every session.
Measurements were taken before and after the 16-week program and included:
Muscle thickness of six lower limb muscles via ultrasound (vastus lateralis, rectus femoris, vastus intermedius, biceps femoris, gastrocnemius medialis and lateralis)
Lean soft tissue of the lower limbs via DXA scanning
Maximum strength via 1-rep max testing for knee extension, knee flexion, and plantar flexion
Whole-body composition (total lean mass, fat mass, bone mass) via DXA
Dietary intake was tracked through 3-day food records at baseline, weeks 4, 8, 12, and post-intervention
