Dietary Intake and Body Composition of Fixed-Shift Workers During the Climacteric: An Intervention Study with Exogenous Melatonin

Poor sleep quality is associated with unhealthy dietary choices and worse body composition among night-shift workers and women during the climacteric period. This study aimed to evaluate the effect of exogenous melatonin administration on the dietary intake and body composition in healthcare workers exposed to fixed-shift work during the climacteric period. A phase II randomized, double-blind, placebo-controlled clinical trial of climacteric women working fixed morning, afternoon, or night shifts was conducted. Baseline data collection included sociodemographic information, sleep parameters, dietary intake, and body composition using bioelectrical impedance. Participants received either 0.3 mg of melatonin or a placebo for three months. Baseline total caloric and carbohydrate intake was higher among night-shift workers than afternoon-shift workers, though afternoon-shift workers a had higher body weight and fat percentage. Post-intervention, caloric intake differences dissipated due to reduced intake among night-shift workers and increased intake among afternoon-shift workers, independent of melatonin or placebo administration. However, differences in body composition persisted. Postmenopausal participants showed reduced fat mass, while premenopausal participants experienced an increase, regardless of intervention. The results suggest that physiological nighttime melatonin doses, administered on non-consecutive nights for three months, were ineffective for changing dietary intake or body composition.