Hale Handbook

Weight-Loss Supplements: What Works (Not Much)

Green tea, garcinia, berberine and "nature's Ozempic." We don't sell any of it, so here's what the evidence really says.

2 min readUpdated November 2026Not reviewed by a doctor

The short version

  • No supplement has good evidence of producing meaningful, lasting weight loss.
  • Supplements aren't FDA-approved before they're sold, and some weight-loss products have been found to contain hidden drugs.
  • Some have caused real harm, including liver injury.
  • Tell your clinician everything you take, since interactions are common.

Why this market is so messy

In the US, dietary supplements don't need FDA approval before they go on sale, and makers don't have to show they work. The FDA generally acts after a problem arises. Over the years it has found many weight-loss products with undeclared drug ingredients, including sibutramine, a prescription drug that was pulled from the market because of heart risks.

The common ones

SupplementClaimEvidenceSafety
CaffeineBoosts metabolismSmall, short-lived effectJitters and poor sleep, and risky at high doses
Green tea extractBurns fatLittle to no meaningful effectLinked to liver injury. Drinking the tea is fine
Garcinia cambogiaBlocks fatLittle to no effectReports of liver injury
ChromiumReduces cravingsVery small effect at bestGenerally well tolerated
CLAReduces fatVery small effectDigestive problems
GlucomannanFills you upMixed, and weakCan cause choking if not taken with water
Bitter orangeFat burnerWeakPossible heart risks
Apple cider vinegarMelts fatVery limitedCan harm teeth and irritate your throat
Berberine"Nature's Ozempic"Small trials, small effects, and quality variesStomach upset, and it interacts with many drugs
Raspberry ketones, white kidney bean, forskolinVariousLittle or no good evidenceUnclear

Nothing on this list comes close to what lifestyle change or prescription medication can achieve in trials. Anything sold as a "GLP-1 booster" or "natural Ozempic" doesn't work like those drugs.

What can be worth taking

These don't cause weight loss, but they may fill a real gap:

  • Vitamin B12 if you're vegan, or if you're older or take metformin and your levels are low.
  • Vitamin D if a test shows you're low.
  • Fiber if you can't get enough from food. More here.
  • Protein powder for convenience. More here.
  • A multivitamin if your diet is restricted or very low in calories.
  • Specific vitamins after bariatric surgery, as directed by your care team. These are essential and lifelong.
  • Folic acid if you could become pregnant.

If you decide to try one anyway

  • Look for a third-party seal such as USP, NSF or ConsumerLab. It verifies what's in the bottle, not that it works.
  • Avoid products with "proprietary blends" or promises of rapid weight loss.
  • Be wary of anything sold through ads on social media.
  • Stop if you get yellow skin or eyes, dark urine, belly pain, a racing heart or severe fatigue, and call your clinician.
  • Report side effects to the FDA's MedWatch program.

Sources

  1. NIH Office of Dietary Supplements: Dietary Supplements for Weight Loss (consumer)
  2. NIH Office of Dietary Supplements: Dietary Supplements for Weight Loss (health professional)
  3. FDA: Contaminated Weight Loss Products, Questions and Answers
  4. FDA: Questions and Answers on Dietary Supplements

This guide is general information, not medical advice. Please check with a clinician before making big changes, especially if you have a health condition, take medication, or are pregnant. Read the full disclaimer.

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