Metabolic & Cardiometabolic
over-the-counter supplements cannot simultaneously build muscle and burn fat
In plain terms: Is there no over-the-counter supplement that both builds muscle and burns fat?
Essentially true — CLA, HMB, carnitine and green-tea extracts do neither meaningfully; the one partial exception is creatine, which nudges lean mass up and fat slightly down, but the fat effect is tiny and a byproduct of training, not real simultaneous fat-burning.
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
The evidence (8)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Whigham 2007 · Am J Clin Nutr | meta-analysis | supports | moderate | Meta-analysis found CLA produces only a trivial fat-mass reduction in humans and no meaningful muscle-building effect. |
| Talenezhad 2020 · Clin Nutr ESPEN | meta-analysis | supports | moderate | Meta-analysis of 37 RCTs found L-carnitine produced modest weight loss only, with no muscle-building effect. |
| Forbes 2019 · J Funct Morphol Kinesiol | meta-analysis | mixed | moderate | Meta-analysis found creatine plus resistance training reduced body-fat percentage by only ~0.55%, a marginal effect alongside lean gains. |
| Lin 2021 · Eur Geriatr Med | meta-analysis | supports | moderate | Meta-analysis found HMB effects on lean mass in older adults are small and controversial, not a reliable muscle-builder plus fat-burner. |
| Desai 2024 · J Strength Cond Res | meta-analysis | mixed | moderate | Meta-analysis found creatine plus training increased lean mass ~1.1 kg and reduced fat ~0.7 kg, but the fat change is small and secondary to training, not true simultaneous fat-burning. |
| Esmaeilnejad 2024 · Br J Nutr | meta-analysis | supports | high | Meta-analysis of 14 RCTs found CLA reduced body weight by under 1 kg with no evidence of simultaneous muscle gain. |
| García-Alonso 2025 · Nutrients | meta-analysis | mixed | moderate | Meta-analysis found HMB added to resistance training gave unclear/limited additional body-composition benefit over training alone. |
| Vázquez Cisneros 2017 · Nutr Hosp | meta-analysis | supports | moderate | Systematic review found green tea/EGCG yields modest fat/weight reduction only, with no anabolic muscle effect. |
Disagree, or know a study we missed?
We grade by evidence, not opinions. The way to weigh in is to point us to a study we haven't cited (check the evidence table above first), or to flag a problem with one we have. Every submission is reviewed; if it holds up, the grade updates and shows in Science Changes Its Mind.
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Educational only, not medical advice. Grades and scores reflect published evidence weighted by study design and quality; see the methodology.