Summary: In this secondary analysis of a 12-month randomised trial in 165 adults with overweight or obesity, 4:3 intermittent fasting improved binge eating and uncontrolled eating scores while daily calorie restriction worsened them (between-group p<0.01). Fasting appetite-related hormones did not differ between the two strategies at any time point.
PICO Summary
| Element | Detail |
|---|---|
| Population | 165 adults with overweight or obesity (mean age 42 years, BMI 34.2 kg/m2, 74% female); secondary analysis of a 12-month randomised controlled trial conducted in the USA. |
| Intervention | 4:3 intermittent fasting (n=84): three non-consecutive fasting days per week, within a prescribed weekly energy deficit of 34%, plus group behavioural support and 300 min/week of aerobic activity. |
| Comparison | Daily calorie restriction (n=81): the same prescribed 34% weekly energy deficit applied evenly across all days, with matched behavioural support and activity prescription. |
| Outcome | At 12 months, binge eating and uncontrolled eating scores decreased with 4:3 intermittent fasting but increased with daily calorie restriction (between-group p<0.01). Within the fasting arm, greater weight loss correlated with reduced uncontrolled eating (r=-0.27, p=0.03), reduced emotional eating (r=-0.37, p<0.01) and increased cognitive restraint (r=0.35, p<0.01). There were no between-group differences in fasting leptin, ghrelin, peptide YY, brain-derived neurotrophic factor or adiponectin at any time point. Effect estimates with 95% confidence intervals and absolute risk measures were not reported in the abstract. |
4:3 Intermittent Fasting vs Daily Calorie Restriction
RCT secondary analysis · overweight/obesity · 12 months
Over 12 months, 4:3 intermittent fasting improved binge and uncontrolled eating while daily calorie restriction worsened them (between-group p<0.01). Fasting appetite hormones did not differ, so the benefit is not explained by the leptin-ghrelin-PYY axis.
Expert Commentary
This secondary analysis offers a measured signal rather than a definitive verdict. The reported finding is that 4:3 intermittent fasting was associated with improved binge eating and uncontrolled eating scores at 12 months, whereas these behaviours deteriorated under daily calorie restriction, and that the two approaches did not differ in fasting appetite-related hormones. The hormonal null is informative: it suggests that any behavioural advantage of intermittent fasting is unlikely to be explained by the classical leptin, ghrelin and peptide YY axis, and the within-arm correlations between weight loss and eating behaviour, while consistent, are associational and cannot establish that improved eating behaviour caused the greater weight loss. The principal limitation is that this is a pre-specified secondary analysis of self-reported questionnaire outcomes in an unblinded, open-label dietary trial, so expectation effects and reporting bias cannot be excluded, and absolute effect sizes with confidence intervals were not provided. Can I use this with my patients? Cautiously, yes, for a motivated adult with overweight or obesity who finds daily restriction psychologically punishing and is considering a structured fasting schedule, while being clear that hormone changes are not the mechanism. Larger trials with objective behavioural endpoints should test whether these eating-behaviour gains are durable beyond one year.
References
Breit MJ, Caldwell AE, Ostendorf DM, Pan Z, Creasy SA, Swanson B, et al. Effects of 4:3 intermittent fasting on eating behaviors and appetite hormones: a secondary analysis of a 12-month behavioral weight loss intervention. Nutrients. 2025;17(14):2385. doi:10.3390/nu17142385
