Does Melatonin Cause Weight Gain? Exploring the Effects on Metabolism and Sleep Quality

By Jessica Migala, Sep 13, 2025

Overall, “melatonin supplements may lead to weight loss,” says Alex Dimitriu, MD, who is double-board certified in psychiatry and sleep medicine and the founder of Menlo Park Psychiatry & Sleep Medicine in Menlo Park, California. One big caveat: “Most of this research is from rat studies, and the doses of melatonin tested have been quite high,” Dr. Dimitriu says. What this tells us is that melatonin is not a supplement that should be used for weight loss. However, preliminary research suggests that you don’t necessarily need to worry that melatonin itself will cause weight gain, if this is a supplement you choose to take under your doctor’s recommendations.

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