Association Between Obesity and Serum Leptin Levels in Brazilian Female Shift Workers

Leptin is a hormone that plays a crucial role in regulating energy homeostasis and it is associated with adiposity. Women engaged in work shifts are often exposed to circadian disruption and metabolic changes that may contribute to increased adiposity and hormonal imbalance. Thus, this study aimed to investigate the association between general and abdominal obesity and serum leptin levels among female shift workers.

This cross-sectional study included a sample of 302 female employees from a group of plastic manufacturing industries in southern Brazil. Serum leptin levels were measured, with values > 15.2 ng/mL classified as elevated. General obesity (body mass index ≥ 30 kg/m²) and abdominal obesity (waist circumference ≥ 88 cm) were assessed. Associations were examined using Poisson regression with robust variance.

The mean age of participants was 35.4 ± 10.1 years. The mean serum leptin concentration in the sample was 33.6 ng/mL (95% Confidence Interval [CI]: 30.6-36.6), and the prevalence of altered serum leptin levels was 78.1% (95% CI: 73.5-82.8). After adjustment for potential confounders, women with obesity showed a 63% higher probability of having elevated leptin levels (Prevalence Ratio [PR] = 1.63; 95% CI: 1.32-2.02; p < 0.001) compared with those without obesity. Additionally, significant associations were observed with work shift and physical activity. However, abdominal obesity was not statistically significant after adjustment.

Obesity was independently associated with elevated serum leptin levels among female shift workers, suggesting that excess adiposity remains a key determinant of leptin dysregulation in this population.