The origins of fitness culture’s most persistent claim reveal a critical gap between initial research scope and lasting industry practice. Moore et al.’s 2009 study, which enrolled just 6 subjects and measured muscle protein synthesis during a narrow 4-hour post-exercise window, established the 20–25 gram protein threshold that later evolved into the ubiquitous 30-gram rule.
Over 14 years, this finding became nutritional dogma despite its limited experimental design. However, subsequent research has challenged these boundaries. Macnaughton et al. (2016) enrolled 30 resistance-trained men and demonstrated that a 40-gram whey protein dose produced significantly greater muscle protein synthesis than 20 grams. More recent work by Trommelen et al. (2023), involving 30+ subjects in whole-body exercise protocols, reinforced this dose-response relationship.
These findings highlight how early evidence with small sample sizes can disproportionately influence long-term industry practice, even when methodological limitations are considerable.
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