Does Melatonin Improve BMI and Reduce Body Fat in Menopausal Women?

Animal studies have shown melatonin reduces body weight, plasma leptin, adiponectin, triglycerides, cholesterol, insulin, and glucose levels beyond its effects on circadian rhythm. Melatonin may suppress peroxisome proliferator-activated receptor gamma thereby reducing fatty acid serum accumulation and bone marrow adipogenesis. There is a dearth of human research on melatonin’s effect on body composition, BMI, or markers of lipid and glucose homeostasis.

A team of researchers indicated that melatonin may reduce adipocyte mass and increase lean muscle mass in a study published in the March 2016 issue of Clinical Endocrinology.

The study was double-blinded, randomized, and placebo-controlled. It enrolled 81 postmenopausal osteopenic Caucasian women aged 56 to 73 years. Patients in the active treatment arm received 1 or 3 mg of melatonin nightly for 12 months, 800 mg calcium, and 20 mcg vitamin D₃ (with a 3-month run-in period of calcium and vitamin D if naïve). The researchers measured body composition with dual X-ray absorptiometry (DXA) at baseline and after 1 year.

Patients’ adipocyte mass fell an average of 6.9%. Their percentage body fat mass also fell by 7.2% and lean body mass increased 5.2%.

The researchers did not see any changes in lipid and glucose metabolism (although animal studies did). A previous study using melatonin and conducted in diabetic patients found no lipid or glucose metabolism changes either. The researchers explain this finding as expected since participants' levels were in the normal range.

The study's design is robust because the researchers double-blinded, controlled for confounders and randomized the participants, and used DXA to measure body composition. Nevertheless, the researchers did not collect serum and urine melatonin levels, bone marrow biopsies, and baseline markers of glucose homeostasis.

This study showed that low-dose melatonin (1 or 3 mg) reduced adipocyte mass and increased lean body mass in postmenopausal women. The authors speculate that melatonin drives an increase in osteogenesis resulting in decreased adipogenesis.