Evaluation of the effect of different intermittent fasting regimens on metabolic parameters in healthy male Wistar rats

This study aimed to evaluate the influence of different intermittent fasting regimens on metabolic parameters in healthy rats and compare them to caloric restriction. A total of 50 adult male Wistar rats (± 90 days old) were randomised into 5 groups: control group (CON); caloric restriction group (CR); time-restricted feeding group (TRF); alternate-day fasting (ADF) group; and alternate-day modified fasting group (ADMF). ADF and ADMF stood out for improving the metabolic parameters in healthy rats by presenting improvements in glucose parameters, greatest weight loss (ADF vs . CON: -16.50±6.16 g; effect size = -5.34; 95% CI: -7.05, -3.04; p < 0.001; ADMF vs . CON: - 21.88±6.66 g; effect size = -5.83; 95% CI: -7.66, -3.36; p < 0.001), and higher HDL (ADF vs . CON: 141.50±10.17 mg/dL; effect size = 3.03; 95% CI: 1.01, 4.45; p<0.001; ADMF vs . CON: 133.10±5.94 mg/dL; effect size = 3.37; 95% CI: 1.22, 4.86; p=0.004). Additionally, ADMF presented a smaller adipocyte area among the fasting regimens (13.92±2.06 area/µm 2 ; effect size = -4.20; 95% CI: -5.45, -2.66; p<0.001 vs . CON), in addition to presenting muscle fibre hypertrophy (71.20±5.16 area/µm 2 ; effect size = 2.93; 95% CI: 1.57, 4.05; p<0.001 vs . CON), followed by ADF (adipocyte area: 19.25±0.87 area/µm 2 ; effect size = -2.19; 95% CI: -3.12, -1.12; p=0.003 vs . CON; muscle fibre: 53.80±6.61 area/µm 2 ; effect size = 2.93; 95% CI: 1.57,4.05; p=0.566 vs . ADMF). The ADF and ADMF groups were more effective among the intermittent fasting regimens analysed in promoting improvements in metabolic parameters in healthy rats.