# The effect of melatonin supplementation on the plasma levels of 2-arachidonoylglycerol, ghrelin and hedonic eating intensity in overweight/obese females: A study protocol for a pilot randomized controlled trial

## TL;DR

This study explores whether melatonin can reduce reward-driven eating in overweight/obese women by affecting certain brain chemicals.

## Contribution

This is a pilot trial investigating melatonin's effect on endocannabinoids, ghrelin, and hedonic eating in overweight/obese females.

## Key findings

- Melatonin may lower plasma levels of 2-arachidonylglycerol and ghrelin in overweight/obese women.
- The study will assess if melatonin reduces hedonic eating intensity over an 8-week period.
- Secondary outcomes like dietary intake and body weight will be monitored for changes.

## Abstract

Hedonic eating, reward-driven eating rather than out of biological needs, has been proposed as one of the important causes of overweight and obesity in recent years. Dopamine, endocannabinoids, opioids, and ghrelin are among the physiological factors associated with hedonic eating. Since the results of some previous animal studies have indicated the effectiveness of melatonin supplementation on the levels of endocannabinoids, and ghrelin, therefore this pilot study will investigate the effect of melatonin supplementation on plasma levels of endocannabinoid 2-arachidonylglycerol, ghrelin, and the intensity of hedonic eating in overweight/obese females.

In a randomized, double-blinded, placebo-controlled study, forty-six women with overweight/obesity and high hedonic eating intensity (total score of power of food scale > 2.5) will be recruited. They will receive either a 5 mg/day melatonin supplement (n = 23) or a placebo (n = 23) for 8 weeks. The primary outcomes, including the plasma levels of 2-arachidonylglycerol and ghrelin, and the intensity of hedonic eating will be assessed at the baseline and end of the study. Additionally, the secondary outcomes (dietary intake, and body weight) will be evaluated at the study’s onset, after four weeks, and upon completion of the intervention. A one-way analysis of covariance (ANCOVA) will be used to detect the effect of melatonin supplementation on outcome variables.

Considering the positive effects of melatonin supplementation in reducing endocannabinoid levels, the expression of the ghrelin hormone gene, the level of ghrelin, and the cannabinoid receptor type 1 gene expression in animal studies, it is possible that in human subjects, it could impact the intensity of hedonic eating by lowering endocannabinoid and ghrelin levels.

The trial was registered with the Iranian Registry of Clinical Trials in June 2023 under the ID number IRCT20080904001197N22.