Creatine for Muscle Gain
When paired with resistance training, creatine reliably produces modest gains in lean body mass and meaningful gains in strength. On its own, without lifting, it does not build muscle.
Why this grade7-layer evidence engine
Four recent high-quality meta-analyses point the same direction, which is why this rates as moderate (Grade A) rather than weak or definitive evidence. Pooling 35 trials (n=1,192), creatine added about +0.68 kg of lean body mass overall and +1.10 kg when combined with resistance training, with men responding more than women (PMID 35986981). For strength, gains were larger and highly significant: roughly +4.43 kg upper-body and +11.35 kg lower-body 1RM in adults under 50 (PMID 39519498), and a smaller but significant +2.12 kg 1RM in older adults (PMID 41062952).
The grade is held at moderate rather than higher because the effect on actual muscle size is small. A meta-analysis of regional hypertrophy found only a trivial standardized effect (SMD 0.11), larger in younger than older lifters (PMID 37432300). The benefit is also strongly conditional on concurrent training and varies by sex and age, so it is an amplifier of a training stimulus, not a standalone muscle builder.
Regulators and major clinics align with this picture. The US FDA raised no objection to creatine's GRAS status, and EFSA concluded a cause-and-effect relationship has been established for creatine plus resistance training improving strength in adults over 55. NIH ODS, Mayo Clinic, and Cleveland Clinic all describe gains in strength and muscle size, while Harvard Health cautions that creatine alone does not build muscle, and a sports-nutrition position statement calls creatine monohydrate the most effective ergogenic supplement. People with kidney disease should consult a clinician first.
Scoring transparency
All scores computed by a 7-layer evidence engine — fully auditable▸View the full decision path (audit trail)
- compute_raw_score — 加權公式: L2×0.30 + L3×0.25 + L5×0.25 + L11×0.10 + L1×0.10 = 0.705
- tier_from_score — 依分數區間映射至 tier letter
- apply_hec_rules — 高階證據未達主導 (1 positive vs 1 negative)，由 raw_score 決定
- tier_strict_requirement_check — Tier 條件達標，未降階
- detect_disputes — 偵測到 0 個 hard + 0 個 soft dispute
- decide_status — 依 tier + dispute 結果決定 status