Research Methodology

Evidence Hierarchy

Not all evidence is equal. We apply a structured hierarchy when evaluating any claim about a supplement or training protocol:

Tier 1 — Meta-analyses and systematic reviews: Pooled analyses across multiple randomized controlled trials carry the most weight. We look at effect sizes, heterogeneity and publication bias in each meta-analysis, not just the headline result.

Tier 2 — Randomized controlled trials (RCTs): Well-designed human RCTs with appropriate sample sizes, placebo controls and pre-registered outcomes are our primary individual study source.

Tier 3 — Position stands and consensus statements: Statements from bodies such as the International Society of Sports Nutrition (ISSN), the American College of Sports Medicine (ACSM) and the Academy of Nutrition and Dietetics are treated as strong secondary evidence when based on the above.

Tier 4 — Observational studies and mechanistic data: These can inform plausibility and generate hypotheses but do not establish efficacy on their own. We label these clearly when cited.

Not used as primary evidence: Animal studies, in-vitro research, anecdotal testimonials and industry-funded studies without independent replication. These are noted when relevant for context but never used to justify efficacy claims.

Study Selection

Sources are identified through PubMed and PubMed Central database searches using the relevant compound or training variable as the primary search term. We also review reference lists of major meta-analyses to identify foundational studies.

We apply the following filters when selecting studies for citation: human subjects, published in peer-reviewed journals, available in full text, and not solely funded by the manufacturer of the product being studied without independent replication. Studies retracted or flagged for data integrity concerns are excluded.

For supplements with a large research base (creatine, caffeine, protein), we rely primarily on the most recent meta-analyses and update when new ones are published. For emerging compounds with limited data, we describe evidence strength explicitly and avoid efficacy language until the research base matures.

Product Testing Protocol

All products reviewed on this site are purchased independently using our own funds. No brand provides free samples in exchange for a review — if a product was received at no cost for any reason, it is disclosed prominently at the top of the page.

Product testing panels run for a minimum of 90 days. Testing groups consist of trained individuals matched for age, training experience and relevant baseline measures (strength levels, body weight). Outcomes tracked include strength performance (1RM and multi-rep maxes on compound movements), body composition changes where applicable, and subjective measures including digestive tolerance, mixability and taste.

Label accuracy is verified by comparing stated doses against the published clinical literature. Products claiming doses below the threshold used in clinical trials are noted. We contact brands for clarification on proprietary blends where relevant.

Rating Criteria

Each product is scored out of 100 using five weighted criteria:

Ingredient quality (30 points): Correct form, full clinical dose, no unnecessary fillers or underdosed actives.

Evidence strength (25 points): How robust is the evidence base for this specific compound at this specific dose?

Third-party testing (20 points): Certification by Informed Choice, NSF Certified for Sport, Labdoor or an equivalent body.

Value for money (15 points): Cost per clinically effective dose, not cost per serving or cost per container.

Real-world performance (10 points): Panel testing results including taste, mixability, digestive tolerance and consistency.

Scores are recalculated whenever a product formula changes or a significant new study is published that alters our assessment of the ingredient's efficacy. Rankings are updated accordingly. Every review page shows its last updated date.

Transparency Commitments

We distinguish clearly between what is established fact, what is a well-supported hypothesis and what is speculative. These labels appear throughout our content:

Strong Evidence: Multiple RCTs, confirmed by at least one meta-analysis, consistent effect across populations.

Emerging Evidence: Promising but limited human data. Findings not yet confirmed by systematic review.

Weak or Conflicting Evidence: Research exists but results are inconsistent, effect sizes are small, or the evidence comes primarily from lower-quality study designs.

If you identify an error, a missing citation or a claim that does not reflect current evidence, contact us at the address on our contact page. We treat corrections seriously and update content promptly.