Patients ask me about supplements constantly. They have seen an ad promising fast results from something natural and want to know whether it is worth a try. The answer is duller than the advertising. The evidence behind most weight loss supplements is thin, and the safety problems are not.
Paul R. Thomas at Columbia University’s Institute of Human Nutrition has reviewed this literature. What he and others find is that these products mostly do not work. The studies that exist tend to be small, short, and funded by the companies selling the product. Where a benefit shows up, it is small. Garcinia cambogia came in at under a kilogram of difference against placebo. That is not what patients are hoping for when they buy it, and it is not remotely close to what lifestyle change or an FDA-approved medication will do (Thomas, 2022).
The marketing claims sort into a few categories. Appetite suppression is credited to hoodia, glucomannan, and saffron. Metabolic or energy boosting gets attributed to caffeine, green tea extract, and bitter orange. Fat absorption blocking is the pitch for chitosan, and reduced fat synthesis for CLA and garcinia cambogia. The proposed mechanisms sound reasonable. The measured effects are close to nothing.
Safety is the more serious issue. Supplements do not have to be proven safe or effective before they are sold, because they are regulated closer to food than to drugs. The FDA can generally act only after harm is documented, which leaves a wide window. Independent testing has repeatedly turned up quality failures, including heavy metal contamination and doses that do not match the label. Some products have been found to contain banned or genuinely dangerous drugs, among them sibutramine, pulled from the market over cardiovascular risk, and phenolphthalein, a carcinogen (Tucker et al., 2018).
The harm is documented rather than theoretical. Roughly 23,000 emergency department visits a year in the United States are attributed to supplements, and weight loss and energy products account for most of them. The usual presentations are palpitations, chest pain, and tachycardia, and the patients are disproportionately young adults in their twenties and early thirties (Geller et al., 2015).
When patients ask what to do, I tell them to be careful. If they are going to use something, single-ingredient products from established national brands are the safer end of the pool, ideally with third-party verification such as USP or NSF. Avoid proprietary blends that will not disclose what is in them. Be suspicious of anything promising to melt fat. If they have a reaction, stop the product, keep the bottle, and report it to Poison Control and the FDA’s MedWatch program.
Supplements are everywhere and the evidence does not support them. Nutrition, physical activity, behavioral support, and where appropriate FDA-approved medication remain both more effective and considerably safer than whatever is currently being advertised.
References
Thomas PR. Weight Loss Supplements. Columbia University Institute of Human Nutrition, 2022.
Geller AI et al. Emergency Department Visits for Adverse Events Related to Dietary Supplements. NEJM. 2015;373:1531-1540.
Tucker J et al. Unapproved Pharmaceutical Ingredients Included in Dietary Supplements Associated With US Food and Drug Administration Warnings. JAMA Network Open. 2018;1(6):e183337.
Board Certified in Obesity Medicine and Family Medicine
This blog is for educational purposes only and does not constitute individual medical advice. Always consult your own physician before making changes to your health, medications, or treatment plan.
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