Sources & method
Where our answers come from.
Every claim on this site comes from peer-reviewed evidence, established sports-science consensus, or named expert sources. Where a method has known limits, we flag them.
Evidence hierarchy
We weight evidence in this order:
- Meta-analyses and systematic reviews of randomised controlled trials. Used wherever the question has been answered at this level.
- Position stands from credible bodies (ISSN, ACSM, NSCA). Used for consensus on practical questions.
- Individual randomised controlled trials in trained populations. Used when meta-analyses don't exist yet.
- Observational and mechanistic studies. Used with appropriate caveats.
- Expert consensus from coaches and researchers with track records. Used where the evidence base is thin.
We name each source on the article it supports, with author, journal and year. Linked where a public abstract or full text is available.
How the calculators are built
Each calculator uses a published formula. We use the formula and the known error bars — no in-house tweaks designed to give nicer numbers.
- Calories & TDEE — Mifflin-St Jeor equation for BMR, multiplied by activity factor (1.2 to 1.9). The most widely validated equation for healthy adults.
- Protein target — based on Morton et al. 2018 meta-analysis (1.6–2.2 g/kg bodyweight for muscle building), adjusted within range by activity level.
- 1RM — Epley and Brzycki formulas. Both work best at 3–10 reps; Brzycki loses accuracy above 10 reps and we flag this on the result.
- Body fat — US Navy circumference method. Accurate to within roughly ±2–3 percentage points for most people. Less accurate at the extremes of bodyweight.
- Weekly volume — Schoenfeld 2017 dose-response meta-analysis ranges (10 to 20 hard sets per muscle per week as optimal).
Editorial process
- Every article goes through a structure check — answer first, key points, expanded sections, sources — before it ships.
- Numerical claims (rep ranges, calorie multipliers, protein doses, volume ranges) are cross-checked against the cited source before publishing.
- Articles carry a "Last updated" date in the page header. When a meaningful update happens — new evidence, corrected number, substantive rewrite — that date moves forward.
What we won't source from
- Influencer claims without an underlying study.
- Supplement company white papers.
- Hype-led training programmes without evidence of practitioner uptake or research backing.
- Anecdote presented as fact.
Conflict of interest
No affiliate links. No sponsored placements. No protein-brand or supplement deals. If we recommend a piece of equipment or a method, it's because we think it's useful — not because someone paid for the mention.
Corrections
Spotted something wrong? Email corrections@muscleclarity.com with the page and the specific issue. Corrections are made promptly and noted in the page's update history.
A note on medical advice
MuscleClarity is an information site, not a clinician or a replacement for one. If something hurts beyond normal training fatigue, or you have a health condition that interacts with training, see a qualified professional.