Melatonin för viktnedgång? Vad säger forskningen?

What is melatonin?

‍Melatonin is a hormone your body produces naturally to regulate your sleep–wake cycle. Levels rise in the evening and signal to your body that it’s time to sleep. Melatonin is often used as a supplement when sleep needs extra support, such as with jet lag, difficulty falling asleep, or a disrupted body clock. Melatonin is not addictive, but it’s recommended for short-term use only.

Can melatonin be used for weight loss?

‍There’s growing interest in how sleep affects metabolism, hunger, and energy balance. Because melatonin influences sleep rhythms, it’s natural to wonder whether it could also affect weight.

Research looking at melatonin and weight shows mixed results. Some studies have seen a very small reduction in body weight, while others have found no effect at all. The limited research available does not show any effect that would be useful as a clinical treatment for weight loss, and there are many factors that influence weight change.

For people who want to lose weight, there are other forms of support and methods that have been shown to be more effective. At the moment, melatonin is not an approved or evidence-based treatment for weight loss.

That said, there may be indirect effects that can influence weight in some cases. Good sleep plays an important role in a healthy lifestyle and weight, and melatonin can help people who struggle with sleep.

Why is melatonin linked to weight?

‍The connection between melatonin and weight loss is mainly based on:

The role of sleep in weight regulation

‍When sleep is insufficient, the body’s natural appetite regulation is disrupted. The hunger hormone ghrelin increases, while the fullness hormone leptin decreases. This can make you feel hungrier even when your body does not need more energy.

At the same time, the brain’s reward system becomes more sensitive to sugary and high-calorie foods, and impulse control is reduced. Lack of sleep can also affect stress levels, which may increase cravings and make emotional eating harder to manage.

Together, this can lead to higher energy intake and make it more challenging to maintain a stable, sustainable weight.

That’s why good sleep and regular daily activity are important for supporting a healthy weight. Melatonin may help by improving sleep. It’s likely that better sleep quality, rather than melatonin itself, is what affects factors linked to weight regulation.

Can melatonin cause weight gain?

‍Existing medical conditions or other medicines can influence how your body responds to melatonin. Any weight gain that happens after starting melatonin is more likely to be due to indirect effects, which in some cases could contribute to weight gain, such as:

Daytime tiredness or drowsiness

‍Some people feel more tired the day after taking melatonin. This can reduce everyday movement or motivation to exercise. Less daily activity can, over time, 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 rather than improve sleep. Poor sleep in itself increases ghrelin, lowers leptin, and can affect appetite and cravings.

How can melatonin help?

‍Melatonin is not a tool for weight loss 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 craving levels
• reduce tiredness-related eating
• increase motivation and wellbeing
• improve recovery and ability to be active

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

Physical activity, diet, and medication

‍Physical activity is an important part of losing weight and maintaining a healthy weight long term. Moving your body increases energy use, which means 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 could be walking, cycling, swimming, going to the gym, or taking part in group classes.

Many people find it easier to stay motivated by varying their activity and trying new things. In general, it’s recommended to combine different types of exercise, such as 150 to 300 minutes of aerobic activity per week, strength training 2 to 3 times a week, and some balance training. This gives broader support for the body and reduces the risk of injury. That said, everyone has different needs and starting points, so it’s about finding what works for you.

It’s important to remember that sustainable weight loss is a long-term process that requires lasting changes to habits and lifestyle. 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 has been difficult despite changes to diet and activity. It’s always important to talk to a doctor before starting any medication. Medicines work best when combined with a healthy lifestyle, where regular movement and balanced eating are the foundation.

Summary
Melatonin is not a primary treatment for weight loss. For people who want to influence their weight, methods with stronger evidence are needed, such as lifestyle changes, nutritionally balanced food choices, 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 useful support for people with sleep difficulties.

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