Melatonin for weight loss? What does the research say?

What is melatonin?

Melatonin is a hormone that your body produces naturally to regulate your body clock. Levels rise in the evening and signal to the body that it is time to sleep. Melatonin is often used as a supplement when sleep needs extra support, for example with jet lag, difficulty falling asleep, or a disrupted sleep–wake rhythm.

Melatonin is not addictive, but it is usually recommended for short-term use only.

Can melatonin be used for weight loss?

There is growing interest in the role sleep plays in metabolism, hunger, and energy balance. Because melatonin affects sleep patterns, it is natural to wonder whether it could also influence body weight.

Research on melatonin and weight shows mixed results. Some studies have seen a small reduction in body weight, while others have found no effect at all.

Overall, the limited number of studies available do not show an effect that would be useful in clinical weight loss treatment. Weight loss is influenced by many different factors. For people who want to lose weight, there is other support and other methods with much stronger evidence. At present, melatonin is not an approved or evidence-based treatment for weight loss.

That said, there may be indirect effects that can influence weight in certain situations.

Good-quality sleep is important for achieving a healthy lifestyle and weight, and melatonin can be helpful for people who struggle with sleep.

Why is melatonin linked to weight?

The connection between melatonin and weight loss mainly comes down to the importance of sleep in weight regulation.

The role of sleep in weight regulation

When sleep is insufficient, the body’s natural appetite regulation is disrupted. Levels of the hunger hormone ghrelin increase, while levels of the fullness hormone leptin decrease. This can make you feel hungrier even when your body does not actually need more energy.

At the same time, the brain’s reward system becomes more sensitive to sweet and high-calorie foods, and impulse control is reduced.

Lack of sleep also affects stress levels, which can increase cravings and make emotional eating harder to manage. Together, this can lead to higher energy intake and make it more difficult to maintain a stable, sustainable weight.

This is why good sleep habits and regular daily activity are important for supporting a healthy weight. Melatonin may help by improving sleep. It is likely the improved sleep quality, rather than melatonin itself, that affects factors linked to weight regulation.

Can melatonin cause weight gain?

Existing medical conditions or other medicines can affect how the body responds to melatonin. Any weight gain that happens around the time melatonin is started is more likely to be due to indirect effects, which in some cases could contribute to weight gain.

Daytime tiredness or drowsiness

‍Some people feel more tired the day after taking melatonin. This can reduce everyday movement or motivation to be active. Less daily activity over time can affect energy balance. Feeling tired during the day can also lead to eating more than usual.

Changes in sleep patterns

‍For a small number of people, melatonin can disrupt sleep rather than improve it. Poor sleep on its own increases ghrelin, lowers leptin, and can affect appetite and cravings.

How can melatonin help?

Melatonin is not a weight loss tool and should not be used for that purpose. However, better sleep can be an important part of a sustainable weight journey.

Good sleep can help to:

• stabilise hunger and cravings
• reduce tiredness-related eating
• improve motivation and wellbeing
• support recovery and ability to be physically active

If the goal is weight loss, approaches that are developed, tested, and approved to influence hunger, appetite, and energy balance are needed.

Physical activity, food, and medication

Physical activity is an important part of losing weight and maintaining a healthy weight in the long term. When you move your body, energy use increases, meaning you burn more calories.

There are many ways to be physically active, and the most important thing is finding something you enjoy and can do regularly. This might include walking, cycling, swimming, going to the gym, or joining group classes.

Many people find it easier to stay motivated if they vary their activities and try new things. General guidance often suggests combining different types of movement, such as around 150–300 minutes of aerobic activity per week, strength training 2–3 times a week, and balance exercises. This gives the body broader support and may reduce the risk of injury. That said, needs and abilities vary, so it is about finding the type and amount of activity that works for you.

It is also important to remember that sustainable weight loss is a long-term process that involves lasting changes to lifestyle and habits. Food choices play a key role. Choosing lower-calorie, nutrient-rich foods with plenty of fibre and enough protein can make a real difference.

For some people, medical treatment can be a helpful addition to lifestyle changes, especially if weight loss is difficult despite changes to food and activity. It is important to always speak with a doctor before starting any medication. Medicines work best when combined with a healthy lifestyle, where movement and balanced eating are the foundation.

Summary

Melatonin is not a primary treatment for weight loss. For people who want to change their weight, approaches with stronger evidence are needed, such as lifestyle changes, nutritionally balanced food, regular physical activity, and, when appropriate, medical treatment.

Good sleep is still an important part of a sustainable weight journey, and melatonin can be a helpful option for people who have difficulty sleeping.

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