Melatonin helps to prevent obesity, studies suggest

Two international studies led by the University of Granada (UGR) have indicated that melatonin can prevent obesity. In addition, its effects are positive against visceral obesity — a particularly worrying fat that accumulates deep in the abdomen, close to vital organs, which can cause serious health problems.

As noted by UGR Professor Ahmad Agil, who led the two studies, “Problems of obesity, overweight and type 2 diabetes are becoming increasingly common in developed and developing countries.” This is a consequence of a bad adaptation of the human genome to factors including a sedentary lifestyle; the consumption of hypercaloric food and drink (with constant and unlimited access); isolation from the cold; industrial manipulation of food with additives such as sweeteners and flavour enhancers; and alteration of circadian biological rhythms due to excessive and chronic exposure to night light, which reduces endogenous melatonin levels.

In an experiment carried out in obese and diabetic adult rats of both sexes, UGR researchers found that chronic administration of melatonin (10 mg per kilogram of bodyweight per day, for three months) prevents obesity to a greater extent than acute treatment and reduces visceral obesity by around 3%. It also ameliorates the muscle-fibre atrophy caused by obesity and generates an increase in mitochondrial activity and content, which explains the reduction in weight gain in both female and male rats. The combination of melatonin administration with bathing in slightly cold water, around 17°C (the average sea temperature), further enhances weight reduction, according to the research.

The results of the team’s studies, published in the journals Antioxidants and Biomedicine & Pharmacotherapy, are in line with previous research which demonstrates that the pharmacological administration of melatonin constitutes a novel strategy in the therapeutic approach to diabesity (central obesity and its type 2 diabetes) and its complications, such as hepatic steatosis, hypertension, lipid alteration, etc. The results also point out that this substance curbs obesity and improves metabolic function through the activation of brown fat and the browning of subcutaneous body fat. Melatonin even promotes adipogenesis of beige mesenchymal stem cells in humans.

With melatonin therapy having helped to help treat visceral obesity in mice, this establishes the need to develop new clinical trials to prove its effectiveness in humans — with preclinical models already showing promising results. In the meantime, Agil recommends that we go about our days (and nights) choosing appropriate activities based on our internal biological clocks.

“During the day, it is good to expose yourself to natural light, do adequate physical activity, choose low-calorie diets loaded with unprocessed foods and replace ... additives with thermogenic spices and herbs, avoid eating between meals, do not wear insulating clothing and keep the heating at a comfortable and cool temperature of around 17°C, as well as showering with cool water,” he said.

During the night, Agil recommends sleeping in the dark, avoiding the use of blue light-emitting devices one or two hours before bedtime and fasting, which increases endogenous melatonin levels. He also advises the elderly to receive low doses of melatonin by physician prescription (because their endogenous melatonin levels are reduced by age), or even high doses in cases of obesity.

“Our main challenge is the application of melatonin and other strategies, such as intermittent fasting, in the field of medicine, especially to address the possibility from a treatment perspective of the aforementioned pathologies (diabesity and its complications) that involve increased oxidative-mitochondrial stress, mitochondrial damage and associated metainflammation (low-grade inflammation of metabolic origin),” Agil said.

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