Effects of Time-Restricted Eating on Circadian Cortisol Secretion and Obesity-Related Metabolic Markers in Cushing’s Disease: A Pilot Study

Purpose: The aims of this study were to evaluate the feasibility of time-restricted eating (TRE) in patients with Cushing’s disease (CD) and assess its effects on body weight and metabolic parameters. Methods: Twelve CD patients in remission with obesity were enrolled in a TRE program restricting food intake to 10:00–18:00. Anthropometric data, glycemic and lipid profiles, and circadian cortisol secretion were assessed at baseline and post-intervention. Serum cortisol levels were measured at multiple time points to evaluate diurnal patterns. Results: Nine patients completed the study. Over the 12-week period, participants showed a significant reduction in body weight, with median values decreasing from 93.8 kg 83.1–106.5 to 82.6 kg 76.9–100.3 (p = 0.011). Body mass index (BMI) also declined from 37.6 kg/m2 34.2–39.7 to 34.4 kg/m2 32.6–38.3 (p = 0.012). No statistically significant changes were observed in fasting glucose, HbA1c, or lipid parameters. Notably, 24 h urinary free cortisol levels significantly decreased (p = 0.01), and serum cortisol showed a downward trend at all measured time points, with the most pronounced reductions during mid-day and evening hours. No clinical or biochemical evidence of CD relapse was observed during the 12-month follow-up. Conclusions: Time-restricted eating is a feasible and well-tolerated dietary approach for patients with CD in remission, promoting weight loss and modest improvements in metabolic markers and cortisol rhythmicity.