top of page

The Effects of Melatonin on Weight (Explained)

Updated: Oct 10, 2021

The hormone melatonin has multiple effects on the body, in this article, I'll explain its effects on weight loss and weight gain. A common question is does it cause weight gain?

Melatonin does not cause weight; in fact, melatonin can actually help with weight loss by decreasing appetite and increasing metabolism, among other effects.

Some research suggests that it increases brown fat, similarly to what ursolic acid does. (1)

Table of Contents:

woman measuring waist circumference

What Does Melatonin Do?

Melatonin is a hormone that your body produces on a regular basis. It is involved in your body's circadian rhythm and helps regulate sleep.

It is produced by the body shortly after it becomes dark, increasing in the early hours of the morning and decreasing throughout the day. It acts on specific receptors in the body.

If you are having trouble sleeping for a short period of time, you may take a synthetic version of melatonin. It helps you fall asleep faster and lowers the chance of waking up throughout the night.

Various hormones are also regulated and altered directly or indirectly from melatonin, either by way of sleep and the circadian rhythm or directly by its effects within the body.

melatonin effects illustration

Melatonin binds to the MT1 and MT2 receptor, MT3 is found in some animals but not in humans.

Combined, the MT receptors are responsible for facilitating many of the effects of melatonin.

Does It Cause Weight Gain?

No, there is no research or study to indicate that melatonin can cause weight gain.

In fact, lower levels of melatonin secretion has been shown to increase appetite and contribute to weight gain. (2)

Melatonin deficiency has also been correlated to obesity and weight gain.

Can It Help With Weight Loss?

Melatonin has multiple effects on fat, it can help reduce weight gain in a few ways.

Promotes Brown Fat

Melatonin intake helps prevent weight gain, partly because it promotes the creation of brown fat, a kind of fat tissue that burns calories rather than storing them. (1)

This type of fat tissue boosts energy expenditure and has additional benefits on insulin resistance and glucose metabolism due to the higher numbers of mitochondria found in brown fat tissue.

brown fat vs white fat illustration

Reduces Appetite

Melatonin lowers food intake by suppressing appetite, it does this by increasing leptin and activating MC4R, a melanocortin system receptor. (3)

A reduced appetite will help reduce calorie intake and therefore weight gain.

Lowers the Production of Adipocytes

Melatonin seems to encourage mesenchymal cells (which grow into either adipose or bone cells) to convert into bone rather than fat. (4)

A lowered production of adipocytes will help reduce the accumulation of fat tissue.

Real-World Research

Interestingly, obesity has been shown to be associated with melatonin insufficiency. (5)

One study observed thirty obese individuals who were given a daily dosage of 10 mg melatonin or placebo along with a calorie-restricted diet for 30 days.

Only the melatonin group saw significant weight loss. The findings from the study also indicate that a calorie restricted diet causes an increase in oxidative stress. (5)

Melatonin supplementation benefitted the participants of the study in a variety of ways, including the following.

  • Helped with weight loss.

  • Increased antioxidant defence.

  • Controlled adipokine secretion.

The results clearly indicate that melatonin should be explored in the treatment of obesity.

Melatonin has been proven by this study to help with weight loss, it seems to be able to control adipokine secretion, reduce oxidative stress and reduce body weight.

Melatonin and Sleep

Sleep is regulated and modulated by melatonin and its effects, it may even reduce the effects of jet lag and insomnia. (6)

It is believed that melatonin is the primary modulator of sleep, it works by changes in light. As it gets dark, melatonin is produced and secreted, as it gets lighter, the opposite happens. (7)

melatonin sleep cycle
Sleep cycle which is largely modulated by melatonin.

It's well-known that melatonin plays a critical role in obtaining high-quality sleep, supplementing with it, like mentioned before, may help reduce the effects of jet lag an insomnia.

When the MT1 and MT2 receptors are activated, the body begins to slow down and prepare itself for sleep.

The typical dosage of melatonin is around 1 mg for adults, though sometimes people take 3, 5 and even 10 mg. The recommended dosage is around 500 mcg to 3 mg.

Melatonin's effects are not dose-dependent; which means that consuming more will not help you fall asleep quicker or better. Taking it about 30 minutes before going to bed will help with sleep.

Interestingly, growth hormone seems to rise slightly higher at a dosage of 5 mg than it does at a dosage of 500 mcg. Though this is likely not a noticeable difference.

The Effect of Sleep on Weight

Sleep deprivation is associated with unfavourable metabolic alterations. Sleeping four hours per night, as opposed to ten hours per night, seems to increase appetite in adults. (8)

Observational studies also point to a connection between sleep deprivation and obesity.

This may be due directly to sleep or due to changes in melatonin levels, this is not clear.

Either way, melatonin helps improve sleep and has direct benefits on weight loss, and sleep itself also seems to have benefits for weight loss and metabolism, as well other health benefits.

Therefore, sleep deprivation can contribute to weight gain, high-quality sleep with adequate melatonin can help reduce weight gain significantly.


Anyone who is taking any medication should speak with their doctor before taking melatonin since it is involved in many bodily systems and interactions are likely.

Melatonin does not cause weight, it can actually help with weight loss via multiple mechanisms and effects in the body.

However, it is not just melatonin that can help with weight loss, getting enough high-quality sleep can help massively.


Written by Billy White

Billy White is a qualified Kinesiologist and Personal Trainer. He is an aspiring bodybuilder, fitness enthusiast, and health and fitness researcher.

He has multiple years of experience within the fitness, bodybuilding and health space. He is committed to providing the highest-quality information.


Further Reading

> Is Exercise Variation Important?

> Is Beta-Alanine & Creatine a Good Combo?



This section contains links to research, studies, and sources of information for this article, as well as authors, contributors, etc. All sources, along with the article and facts, are subjected to a series of quality, reliability, and relevance checks.

Real Muscle primarily uses high-quality sources, such as peer-reviewed publications, to back up the information in our articles. To understand more about how we fact-check and keep our information accurate, dependable, and trustworthy, see more about us and our process.

This evidence-based analysis of melatonins effect on weight features 8 references, listed below.

1. Bruno Halpern, Marcio C.Mancini, Clarissa Bueno, Isabella P.Barcelos, Maria Ednade Melo, Marcos S.Lima, Camila G.Carneiro, Marcelo T.Sapienza, Carlos Alberto Buchpiguel, Fernanda Gaspardo Amaral, José Cipolla-Neto. Melatonin Increases Brown Adipose Tissue Volume and Activity in Patients With Melatonin Deficiency: A Proof-of-Concept Study. Diabetes. (2019, May) (Government Authority) ✔

2. Walecka-Kapica E, Klupińska G, Chojnacki J, Tomaszewska-Warda K, Błońska A, Chojnacki C. The effect of melatonin supplementation on the quality of sleep and weight status in postmenopausal women. Prz Menopauzalny. (2014, Dec) ✔

3. Piccinetti CC, Migliarini B, Olivotto I, Simoniello MP, Giorgini E, Carnevali O. Melatonin and peripheral circuitries: insights on appetite and metabolism in Danio rerio. Zebrafish. (2013, Sep) ✔

4. Kamal Patel, Team. Melatonin. Sleep. (2019, Sep) ✔

5. Szewczyk-Golec K, Rajewski P, Gackowski M, Mila-Kierzenkowska C, Wesołowski R, Sutkowy P, Pawłowska M, Woźniak A. Melatonin Supplementation Lowers Oxidative Stress and Regulates Adipokines in Obese Patients on a Calorie-Restricted Diet. Oxid Med Cell Longev. (2017) ✔

6. Costello RB, Lentino CV, Boyd CC, O'Connell ML, Crawford CC, Sprengel ML, Deuster PA. The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature. Nutr J. (2014, Nov) ✔

7. Gooley JJ, Chamberlain K, Smith KA, Khalsa SB, Rajaratnam SM, Van Reen E, Zeitzer JM, Czeisler CA, Lockley SW. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. J Clin Endocrinol Metab. (2011, Mar) ✔

8. Katherine Zeratsky, Mayoclinic. Sleep and weight gain: What's the connection? Healthy Lifestyle. (2020, April) (Non-Profit Scientific Organisation) ✔

Citations with a tick indicate the information is from a trusted source.


The information provided in this article is not intended to replace professional medical advice, diagnosis, or treatment. Always seek the guidance of a physician or other competent professional before following advice or taking any supplement. See our terms and conditions.

Real Muscle leads the way in terms of transparency and privacy, which is why we want to let you know that some of the outbound links in this article may be affiliate links in which we may earn a small commission through. Despite this, our product recommendations are completely unbiased.

Give Your Feedback

How would you rate this article?TerribleNot greatSatisfactoryGoodPerfectHow would you rate this article?

Get Your Free Workout Guide

Sign up to receive your free guide to workouts, including 5 of our best tips guaranteed to help you achieve your goals! Sign up now.

Great! Check your inbox.

Our Promise

Real Muscle is a fitness, health, and bodybuilding information publishing company working to make honest, accurate, and evidence-based information easy to find. We are working hard to improve the health and fitness of everyone.

Our evidence-based articles are based on the latest, most trustworthy studies and research, every statement is cited. Read the policy here.

Our evidence-based articles are regularly updated, scientifically reviewed, and fact-checked by subject matter experts. Meet the team here.

All of our articles are put through the most rigorous of editorial standards to ensure the highest-quality article possible. See our process here.

bottom of page