effect of intermittent fasting on appetite and dietary intake

Background: the role of 5:2 intermittent fasting (if) in influencing appetite to improve dietary compliance and sustain long-term weight loss is unclear. this study aimed to evaluate changes in appetite on fasting days for an if group and to compare dietary intakes between the if and continuous calorie restriction (cr) groups.methods: a three-month longitudinal study was conducted using data from the iranian national obesity registry. eligible participants (body mass index (bmi) ≥25 kg/m², 18-65 years old) were assigned to a 5:2 if group (n=40) or a cr group (n=42) for 12 weeks. to evaluate appetiterelated variables on fasting days, we used a validated visual analog scale to measure hunger, fullness, estimated eating capacity, and other factors related to appetite. these measurements were taken at the beginning and the end of fasting days. to assess dietary intake, we conducted 3-day food recalls at baseline and after three months.results: both groups showed significant reductions in macro- and micronutrient intakes compared to baseline values, but no significant differences between the two groups were observed (p>0.05). hunger and estimated eating capacity significantly decreased on fasting days (p=0.02 and p<0.001, respectively), and fullness significantly increased (p=0.03).no significant changes were observed in satisfaction (p=0.88) or eating desire intensity (p=0.41).conclusion: these findings suggested that the 5:2 if regimen effectively reduced hunger and estimated eating capacity; while increasing fullness on fasting days. these effects may contribute to the efficacy of if as a weight loss strategy over a 12-week period.