SUPPLEMENTS · MYTH BUSTED
MYTH BUSTED
This is the myth that has kept more women under-fuelled than almost any other. It gets repeated in gyms, on social media, and by well-meaning friends. The research is unambiguous — and has been for years. Here is what the evidence actually shows.
A 2018 systematic review and meta-analysis published in the British Journal of Sports Medicine, analysing 49 studies and over 1,800 participants, found that protein supplementation significantly improved muscle mass and strength in adults performing resistance training — and was equally effective in males and females (Morton et al., 2018).
Critically, the same analysis found that benefits plateaued at around 1.6g of protein per kilogram of bodyweight. Beyond that threshold, additional protein produced no further muscle gains. A scoop of whey protein after training moves you toward an evidence-based target — it does not trigger uncontrolled growth.
The primary driver of the large-scale muscle hypertrophy seen in male bodybuilders is testosterone. Women produce roughly 10–20 times less testosterone than men — a biological reality that fundamentally limits the rate and ceiling of muscle growth regardless of protein intake.
A 2024 pilot study published in Nutrients examining women performing resistance exercise found that protein supplementation improved lean mass and body composition — without producing the bulk that the myth predicts. The outcome was a stronger, leaner physique, not a larger one.
“The 2018 BJSM meta-analysis of 49 studies found protein supplementation equally effective in men and women — with gains plateauing at 1.6g per kg. Not bulk. Recovery.”
Significant muscle hypertrophy requires a sustained caloric surplus, high-volume progressive resistance training over months or years, and favourable hormonal conditions. Most recreationally active women are not in a caloric surplus, are not training at hypertrophic volumes, and do not have the testosterone levels required to produce the size associated with the myth.
A 2025 systematic review with multilevel meta-analysis in Frontiers in Nutrition confirmed that protein supplementation combined with exercise in women improved muscle fitness — defined as strength and lean mass — without adverse body composition outcomes. The conclusion: protein supports performance adaptations, not bulk.
Whey protein is derived from milk. It contains the same amino acids found in chicken, eggs, and Greek yoghurt — just in a more concentrated, convenient form. A standard serving provides approximately 25g of protein and 110–130 calories. It does not contain hormones, it does not override your physiology, and it does not cause muscle growth independently of training.
The 2023 research on protein requirements for trained women (Mallinson et al., 2023, PubMed) confirmed that hitting protein targets after repeated bouts of resistance exercise is essential for muscle protein synthesis — and that supplementation is a practical and effective way to achieve this on training days.
Protein powder will not make you bulky. The fear around it is not supported by evidence — it is supported by a misunderstanding of how muscle growth works, and by decades of imagery associating supplements with extreme male physiques.
What protein supplementation will do, according to the research: support muscle recovery, reduce soreness between sessions, help maintain lean mass during fat loss, and make hitting your daily protein targets easier on busy days. For active women consistently falling short of 1.6g per kg, it is one of the most evidence-backed additions you can make.
SOURCES & RESEARCH
Morton RW et al. (2018). A systematic review, meta-analysis of protein supplementation on resistance training-induced gains. British Journal of Sports Medicine.
Mallinson JE et al. (2023). Protein dose requirements to maximise skeletal muscle protein synthesis in young trained women. PubMed 37787091.
Zhou C et al. (2025). Effects of multi-ingredient protein supplementation combined with exercise in healthy women: systematic review. Frontiers in Nutrition.
Ballesteros-Torres JM et al. (2024). Impact of protein supplement source on body composition in women practicing resistance exercise. Nutrients, 16(2), 321.