Nightly fasting duration is not associated with the prevalence of metabolic syndrome among non-shift workers: The Furukawa Nutrition and Health Studymx.

Objectives: While several experimental studies in animals and humans have suggested the protective effect of nightly fasting duration (NFD) against cardiometabolic risk factors, few population-based studies have been conducted. This study aimed to investigate the association between NFD and metabolic syndrome (MetS) among Japanese non-shift workers.

Methods: A subset of 1054 non-shift workers from the Furukawa Nutrition and Health Study were included in this analysis. Participants completed dietary and lifestyle surveys during a periodic checkup. NFD was defined as the time between dinner and breakfast and was categorized into four groups (ie, ≥12 hours, 11 hours, 10 hours, and ≤9 hours). MetS was defined as ≥3 of the following components: high waist circumference (≥90 cm [men] and ≥80 cm [women]), high triglycerides (≥150 mg/dL), low high-density lipoprotein cholesterol (<40 mg/dL [men] and <50 mg/dL [women]), hypertension (systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥85 mm Hg), and high fasting glucose (fasting plasma glucose ≥100 mg/dL or hemoglobin A1c ≥5.6%). A multivariable logistic regression model was used to examine the association between NFD and MetS.

Results: The odds ratios (95% confidence intervals) of MetS for the highest (≥12 hours) through lowest (≤9 hours) NFD categories were 1.00 (reference), 0.83 (0.51-1.35), 0.83 (0.48-1.43), and 0.80 (0.43-1.48) (P for trend = 0.50) after adjusting for covariates. Further analyses on the relationship between NFD and each MetS component found no significant associations.

Conclusions: We did not find any evidence of a significant association between NFD and MetS among non-shift workers in Japan.