Evening chronotype is associated with severe NAFLD in obesity

Chronotype, i.e., the individual attitude to carry out the daily activities at a certain time of the day, has been reported to play a role in metabolic diseases. Thus, the aim of our study was to investigate the association of non-alcoholic fatty liver disease (NAFLD) with chronotype categories in individuals with obesity.

In this cross-sectional study, participants underwent to anthropometric, biochemical, and the Visceral Adiposity Index (VAI) assessment. Chronotype categories were assessed by the Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ). The following indirect indices of NAFLD were calculated: Liver Fat Equation (LFE), Hepatic Steatosis Index (HSI) and Index of Non-alcoholic steatohepatitis (ION).

The study population consisted of 87 participants (40.3 ± 12.3 years; BMI 45.6 ± 6.3 kg/m²; 64F/23M). According to the chronotype score, 31.0% were morning (MC), 36.8% were intermediate (IC), and 32.2% evening chronotype (EC). Individuals with IC were significantly younger than those with MC and EC (p = 0.002 and p = 0.047, respectively). EC presented significantly higher BMI (p < 0.001), waist circumference (p = 0.007), and hip circumference (p = 0.001) than MC. Moreover, EC had higher BMI (p < 0.001) and waist circumference (p = 0.011) than IC. All participants presented NAFLD (HSI ≥ 36 and LFE ≥ 5). Nevertheless, only individuals with EC were above the threshold of non-alcoholic steatohepatitis evaluated as ION index (ION ≥ 50). Individuals with EC presented significantly higher VAI (p = 0.036), LFE (p = 0.034), HSI (p < 0.001) and ION (p = 0.014) than MC, also after the adjustment for age, gender, and BMI.

EC is associated with more severe NAFLD independently of age, gender, and BMI than MC and IC in individuals with obesity.