The Study
The Effect of 4:3 Intermittent Fasting on Weight Loss at 12 Months
This study is like a fair race between two diets — one where you eat less 3 days a week, and one where you eat less every day. It found that the 3-days-a-week diet helped people lose a little more weight, but only because everyone got lots of help and coaching. It doesn't prove that one diet is better for everyone, just for people in this special program.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
People who ate very little on 3 random days a week and ate normally the other 4 days lost more weight than people who ate a little less every single day — even though both groups were supposed to cut the same total calories per week.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 570 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Losing nearly 3 kg more over a year is meaningful — it’s like losing a small suitcase of weight, and more people stuck with the plan, which matters for long-term success.
- 2The 3-days-a-week group lost 2.89 kg more than the daily-restriction group; 58% lost at least 5% of their body weight vs.
- 347% in the daily group; fewer people quit the 3-day plan (19% vs.
- 429.6%).
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Annals of internal medicine
Year
2025
Authors
V. Catenacci, Danielle M. Ostendorf, Zhaoxing Pan, Laura K Kaizer, S. Creasy, A. Zaman, A. Caldwell, Jared H Dahle, Bryan Swanson, Matthew J Breit, Kristen Bing, Liza T Wayland, Shelby L Panter, Jared J Scorsone, Daniel H. Bessesen, Paul S. MacLean, Edward L. Melanson
Related Content
Claims (10)
Adults with overweight or obesity in Japan who use a brief web and mobile program based on intermittent fasting and meal support lose weight.
In a 12-month behavioral weight management program, adults with overweight or obesity who followed a 4:3 intermittent fasting schedule were less likely to drop out than those who followed daily caloric restriction.
In adults with overweight or obesity following a 12-month behavioral weight loss program, intermittent fasting with 80% energy restriction on three nonconsecutive days per week led to 2.89 kg more weight loss than daily calorie restriction at 34% deficit, and 58% of participants lost at least 5% of their body weight compared to 47% in the daily restriction group.
Among adults with overweight or obesity who receive intensive behavioral support, those following a 4:3 intermittent fasting schedule reduce their calorie intake by 4.11% more on average over 12 months than those following daily caloric restriction.
In a 12-month weight loss program for adults with overweight or obesity, a pattern of eating that involves severe calorie restriction on three nonconsecutive days per week led to slightly more weight loss and a higher rate of achieving at least 5% weight loss compared to daily moderate calorie restriction.
People who complete a 12-week intermittent fasting program maintain their weight loss for at least one year after stopping the program.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.