Evidence Base

The studies behind every answer.

Original papers. Full analysis. Every finding linked to its DOI so you can check our work.

The protein gap nobody told you about after 40 Researchers found that the per-meal protein dose that maxes out muscle building in younger adults only gets older adults 60 percent of the way there. But the peak building rate? Identical. Moore et al. · 2015 · Journals of Gerontology - Series A Biological Sciences and Medical Sciences · n=108

The Creatine Tub You Stopped Using Researchers pooled 143 trials to answer the creatine question: real muscle or just water? The answer involves an MRI scanner, a price comparison, and a myth about loading. Pashayee-Khamene et al. · 2024 · Journal of the International Society of Sports Nutrition · n=3,655

14,600 days of stable metabolism — the age-30 crash never happened The largest metabolic database ever assembled shows your metabolism holds from 20 to 60. The real decline starts 33 years later than the myth claims, and it is cellular. P et al. · 2021 · Science · n=6,421

151 Trials Say Your 75-Minute Workout Is Triple the Volume for Half the Result The largest network meta-analysis ever conducted on training volume in older adults found a 2.22-to-1 advantage in muscle growth for shorter programs. The data doesn't just suggest doing less — it identifies exactly how much less. Radaelli et al. · 2025 · Sports Medicine · n=6,306

McMaster Called It 'Hype.' Three Evidence Domains Explain Why Hormones Don't Predict Muscle Growth. A narrative review from one of the world's most respected exercise science labs examined whether hormones drive muscle growth across three independent evidence domains: post-workout spikes, sex-based testosterone differences, and menstrual cycle periodization. The answer was the same from all three. Every et al. · 2024 · Exercise and Sport Sciences Reviews

Same Weight Lost, Different Body After 50 20 trials show the protein threshold that determines whether weight loss after 50 costs you muscle — or preserves it. Kim et al. · 2016 · Nutrition Reviews · n=20

The Test That Can’t See Its Own Cure A meta-analysis of 24 studies found that the standard screening tool for sarcopenia is the least responsive measure of whether exercise actually works. The leg strength test told a completely different story. Yan et al. · 2025 · Aging Clinical and Experimental Research · n=951

Her Scale Said Nothing Changed. 101 Studies Showed Why. Researchers pooled 5,697 postmenopausal women and found that one exercise type rewrites body composition without moving the number on the bathroom floor. The data also revealed why age is irrelevant to the result. Khalafi et al. · 2023 · Frontiers in Endocrinology · n=101

The Creatine Evidence Was Built on People Who Don't Buy It A meta-analysis of 1,093 adults revealed that 69% of the creatine evidence base is women over 55 — the demographic least likely to use the supplement. The strength benefit landed where aging hits hardest, with a safety record the kidney concern doesn't survive. Sharifian et al. · 2025 · European Review of Aging and Physical Activity · n=1,093

Muscle Memory After 60: The Comeback Was Faster Than the Original Build Men aged 58 to 77 lost just 5 to 15 percent of their strength after three months off. When they returned, the comeback took a third less time and ended at a higher peak. The movement they'd trained most came back fastest. Blocquiaux et al. · 2020 · Experimental Gerontology · n=0

Studies

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