Summary: In a secondary analysis of a 12-month randomized trial of 165 adults with overweight or obesity, 4:3 intermittent fasting reduced binge eating and uncontrolled eating scores while these worsened with matched daily calorie restriction (p < 0.01 for between-group differences). Within the fasting arm, greater weight loss correlated with improved eating behaviors, but there were no between-group differences in fasting appetite hormones at any timepoint.
PICO Summary
| Element | Detail |
|---|---|
| Population | 165 adults with overweight or obesity (mean age 42 ± 9 years, BMI 34.2 ± 4.3 kg/m², 74% female); secondary analysis of a single-centre 12-month randomized controlled trial, USA. |
| Intervention | 4:3 intermittent fasting (three non-consecutive fast days per week) with a matched 34% weekly energy deficit, group behavioral support, and a prescription to reach 300 min/week of moderate aerobic activity (n = 84). |
| Comparison | Daily caloric restriction with the same 34% weekly energy deficit and identical behavioral support and activity prescription (n = 81). |
| Outcome | At 12 months, binge eating and uncontrolled eating scores decreased with 4:3 fasting but increased with daily restriction (p < 0.01 for between-group differences). Within the fasting arm only, greater weight loss correlated with lower uncontrolled eating (r = -0.27, p = 0.03), lower emotional eating (r = -0.37, p < 0.01), and higher cognitive restraint (r = 0.35, p < 0.01). There were no between-group differences in fasting leptin, ghrelin, peptide YY, BDNF, or adiponectin at any timepoint. No adjusted effect sizes, 95% CIs, or ARR/NNT were reported for this secondary analysis. |
Expert Commentary
This secondary analysis suggests that, at a matched energy deficit, a 4:3 fasting schedule is associated with more favourable eating-behavior trajectories than daily calorie restriction over 12 months, while leaving fasting appetite hormones unchanged between groups. The signal is consistent and the between-group contrast for binge and uncontrolled eating reached significance, which is reassuring given long-standing concern that fasting protocols might provoke disordered eating. The verdict, however, should be read as hypothesis-generating rather than confirmatory. These are exploratory psychometric and hormonal endpoints, not the trial’s pre-specified primary outcome, and the weight-loss association is a within-arm correlation that cannot establish that improved eating behavior drove the weight difference; reverse causation and shared confounding are equally plausible. The principal limitation is that a behavioral dietary trial cannot be blinded, so reporting of binge and uncontrolled eating on self-report questionnaires is open to expectancy and social-desirability bias that may favour the novel arm. No adjusted effect sizes or confidence intervals were provided, and the hormone panel was null. Can I use this with my patients? Cautiously yes, for motivated adults with obesity who find daily restriction psychologically burdensome and want a structured alternative, while screening for and excluding active eating disorders. Future trials should pre-register eating-behavior endpoints and test mediation against weight change directly.
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