Classic vs. High-Fat Intermittent Fasting: Impacts on Body Composition, Eating Behaviour, and Diet Satisfaction

This study aimed to examine the effects of two different intermittent fasting protocols, distinguished by macronutrient distribution (classical intermittent fasting versus high-fat, low-carbohydrate intermittent fasting), on body composition, eating behaviour, and diet satisfaction. The study was conducted at a single centre and included 44 adult women who consulted a dietitian. Participants were randomly assigned, in a single blind manner, to one of two groups. The diet interventions were applied for six weeks; all participants completed this period. Body composition, eating behaviour, and diet satisfaction were evaluated. Data were analysed using SPSS version 21.0. The dietary interventions resulted in significant improvements in body composition in both groups (p < 0.05); however, no significant differences were observed between the groups compared to baseline (p > 0.05). Participants' eating behaviour improved across all subscales in both groups (p < 0.05). Importantly, the classical diet group showed significantly greater improvements compared to baseline in cognitive restraint (adjusted post-intervention mean: 19.66 vs. 17.38; p = 0.006) and emotional eating (adjusted post-intervention mean: 9.66 vs. 12.97; p < 0.001) compared to the high-fat group. Satisfaction with the diet did not differ significantly between groups (classical: 41.0; high-fat: 34.0) (p = 0.063). This study demonstrated that classical and high-fat intermittent fasting models led to improvements in body composition and eating behaviour compared to baseline measurements. Further research with longer durations and diverse populations, including men, is needed to fully understand the impact of macronutrient distribution within intermittent fasting.