Melatonin supplementation, at a dose of 8 mg a day, may be useful in the treatment of obesity as it contributes to a significant reduction in body weight. This is the conclusion of the latest meta-analysis published this summer, even though the molecule has a long history of publications exploring its potential for treating obesity and intrinsic metabolic dysregulation.
As a pineal hormone, melatonin is a molecule associated in one way or another with all physiological systems, with integrative functional roles in central nervous system activity, sleep and wake cycles, energy metabolism and thermoregulation.
Several animal studies have provided insights into the roles of melatonin on brown adipose tissue (BAT) volume expansion and metabolic capacity. In humans, a first small but important proof-of-concept study was recently conducted: daily administration of 3 mg melatonin for three months increased Bat volume in the four patients examined, people who had a hormone deficiency due to radiotherapy or surgical removal of the pineal gland.
In a 2016 double-blind randomised clinical trial, a group of postmenopausal women diagnosed with osteopenia and treated with melatonin (1 and 3 mg/day) for 12 months showed an improvement in body composition, as measured by Dexa (dual-energy X-ray absorptiometry), compared to women who received placebo. The study’s investigators also found a 6.9% reduction in fat mass combined with a 5.2% increase in lean mass in the group receiving melatonin. It should be noted, however, that this study did not report the participants’ dietary patterns or physical activity levels.
In an investigation combining melatonin supplementation (10 mg/day 1 h before bedtime) in combination with a low-calorie diet (1,000 to 1,200 kcal/day for women and 1,400 to 1,600 kcal/day for men) in adult patients with obesity, the melatonin intervention was able to further increase weight loss, from 113.6 to 105.9 kg, compared with the group receiving placebo (114.4 to 109.8 kg). In addition, levels of malondialdehyde, a biomarker of oxidative stress, decreased more in the melatonin group, from 34.3 to 24.5 nmol/g Hb, than in the placebo group, from 30.1 to 27.4 nmol/g Hb. This is an interesting finding given that obesity-induced oxidative stress is correlated with an increased risk of insulin resistance and increased accumulation of abdominal fat.
Assessing the effect on sleep quality after menopause, researchers have found a significant reduction in body mass index in normal-weight and overweight women taking a combination therapy with melatonin supplementation (5 mg/day for 24 weeks) and a balanced diet of 1,500 kcal/day.
In another study in overweight postmenopausal women, melatonin supplementation at a dose of 5 mg/day combined with fluoxetine 20 mg/day for 24 weeks resulted in an improvement in sleep quality, as well as a reduction in appetite and Bmi, from 30.9 to 26.3 kg/m².
In the meta-analysis published in 2017, which covered seven clinical studies and a total of 244 participants, melatonin supplementation alone proved ineffective in inducing weight loss, but showed a positive effect when combined with other strategies. Furthermore, several studies have shown that supplementation does not improve body composition in obese women, nor in diabetic patients, nor in patients with metabolic syndrome, but these studies reported no data on dietary intake or physical activity levels and differed considerably in their methodologies. This is why, at present, the actual role of melatonin as an adjuvant for the treatment of obesity is far from being fully understood.
It may be possible that supplementation is an effective adjunct in obesity treatment in individuals who initially have lower levels of melatonin or are somehow unresponsive to their endogenous melatonin.
Bibliography
Melatonin supplementation and anthropometric indicators of obesity: a systematic review and meta-analysis. Nutrition. 24 June 2021.
Melatonin supplementation in the management of obesity and obesity-associated disorders: a review of physiological mechanisms and clinical applications. Pharmacol Res, 163 (2021).
Melatonin increases brown adipose tissue volume and activity in patients with melatonin deficiency: a proof-of-concept study. Diabetes, 68 (5) (2019), pp. 947-952.
The effect of melatonin supplementation on the quality of sleep and weight status in postmenopausal women. Menopause Rev., 13 (6) (2014), p. 334.
English