Fat burners
Little or no proven effect, and real risks, up to hidden drugs in the product
What it is
A catch-all name for supplements that promise to boost metabolism, curb appetite and reduce body fat. The contents vary: botanicals, caffeine, dietary fibre, minerals. One product can contain dozens of ingredients, sometimes more than 90.
Benefits
IOC: the evidence is far from conclusive, and for the vast majority of these supplements there is none. Green tea and CLA: a small to trivial effect (IOC). Garcinia: small short-term weight loss of uncertain clinical relevance. Synephrine: no significant effect on weight or body composition. Yohimbe: no effect on weight, very little research (NIH).
Dose
There are no recommended doses. Products are hard to compare: ingredients are not standardised and many products are proprietary blends, so the amounts of active compounds may differ (NIH).
When to take it
The sources give no advice on timing.
Who it's for
The sources name no one who needs fat burners. The basis of long-term weight loss is a healthy dietary pattern, fewer calories and physical activity (NIH).
Who can skip it
Talk to your doctor before taking one, and this matters most if you have high blood pressure, diabetes, or liver or heart disease (NIH). Athletes subject to doping tests: AIS places bitter orange and synephrine in Group D, not to be used.
Safety
FDA: many weight-loss products are likely to contain dangerous hidden ingredients, often sibutramine, a drug pulled from the US market in 2010 over safety. Synephrine raises blood pressure with longer use. 800 mg of green tea EGCG a day or more raised liver enzymes (EFSA). Yohimbine at 20 mg or more: significant concerns, with hypertension, tachycardia, heart attack and death reported. The FDA banned ephedra from supplements in 2004 (NIH).
This is a summary of public sources, not medical advice. If you have a health condition, are pregnant or take medication, talk to a doctor before taking a supplement.
Sources
- Dietary Supplements for Weight Loss — Fact Sheet for Health Professionals . NIH Office of Dietary Supplements, 2022.
- IOC consensus statement: dietary supplements and the high-performance athlete . International Olympic Committee / British Journal of Sports Medicine, 2018.
- Weight Loss Product Notifications . U.S. Food and Drug Administration, 2026.
- Scientific opinion on the safety of green tea catechins . European Food Safety Authority, 2018.
- The Safety and Efficacy of Citrus aurantium (Bitter Orange) Extracts and p-Synephrine: A Systematic Review and Meta-Analysis . Nutrients, 2022.
- The Use of Garcinia Extract (Hydroxycitric Acid) as a Weight loss Supplement: A Systematic Review and Meta-Analysis of Randomised Clinical Trials . Journal of Obesity, 2011.
- AIS Sports Supplement Framework — Group D . Australian Institute of Sport, 2026.
Other supplements
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