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 with caloric restriction. A total of fifty 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 v. CON: −16·50 (sd 6·16) g; effect size = −5·34; 95 % CI: −7·05, −3·04; P < 0·001; ADMF v. CON: –21·88 (sd 6·66) g; effect size = −5·83; 95 % CI: −7·66, −3·36; P < 0·001) and higher HDL (ADF v. CON: 141·50 (sd 10·17) mg/dl; effect size = 3·03; 95 % CI: 1·01, 4·45; P < 0·001; ADMF v. CON: 133·10 (sd 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 (sd 2·06) area/µm²; effect size = −4·20; 95 % CI: −5·45, −2·66; P < 0·001 v. CON), in addition to presenting muscle fibre hypertrophy (71·20 (sd 5·16) area/µm²; effect size = 2·93; 95 % CI: 1·57, 4·05; P < 0·001 v. CON), followed by ADF (adipocyte area: 19·25 (sd 0·87) area/µm²; effect size = −2·19; 95 % CI: −3·12, −1·12; P = 0·003 v. CON; muscle fibre: 53·80 (sd 6·61) area/µm²; effect size = 2·93; 95 % CI: 1·57, 4·05; P = 0·566 v. ADMF). The ADF and ADMF groups were more effective among the intermittent fasting regimens analysed in promoting improvements in metabolic parameters in healthy rats.