What happens between two meals
Once a meal is digested, the digestive tract switches to a pattern of its own: a wave of muscle contractions runs from the stomach through the small intestine at intervals and, according to the usual explanation, pushes leftovers along. Specialists call it the migrating motor complex. It only runs while you're not eating. Every meal, even a small snack, interrupts it.
The strongest phase of this wave is triggered by, among other things, the hormone motilin. A 2021 review from the University of Leuven describes motilin as the main trigger for hunger returning after a meal. So when your stomach growls a few hours after eating, that's part of this pattern. It doesn't mean you're missing something right away.
Fewer or more meals: what studies find
The most recent meta-analysis of randomised trials (2023, 16 trials) compared three or fewer with four or more meals a day. It found no discernible advantage for either pattern, not for weight, blood lipids, blood sugar or similar metabolic markers. The authors rate the certainty as very low: 15 of the 16 trials had a high risk of bias.
A network meta-analysis from Freiburg (2020, 22 trials, same calorie intake in each) goes a little further. With two meals a day, participants lost about 1 kilogram more on average than with three, with moderate certainty. For even fewer meals the results were uncertain. A meta-analysis in JAMA Network Open (2024, 29 trials) also found small weight effects for fewer meals and for eating windows, and itself calls their importance uncertain.
Snacks: when and what matter more than how often
The ZOE PREDICT study took a close look at around 850 adults, three quarters of them women. 95 per cent ate at least one snack a day, on average just over two. How often someone snacked was not linked to their blood markers. Snack quality showed a link with less favourable blood lipids and insulin, but it no longer held after correcting for the many comparisons. Timing was clearer: people who snacked from 9 pm had slightly higher long-term blood sugar (HbA1c) than with snacks at other times.
This is an observational study, it shows associations, not causes. For the question of whether a snack does harm, that means: an apple in the afternoon is probably something different from crisps at 11 pm.
And the cycle?
A small study had 12 premenopausal women eat only within a four- to six-hour window for eight weeks. Testosterone, androstenedione and the binding protein SHBG did not change, DHEA fell. Oestrogen and progesterone were not measured in these women. All of them had obesity, and twelve is too few for a general statement. There's no indication that normal breaks between three meals disturb the cycle.
When longer breaks aren't a good idea
People who try longer breaks often feel hungrier at first. A 2025 meta-analysis found slightly more hunger with an eating window than with the same calorie intake and no time limit, in adults with overweight.
Different rules also apply in pregnancy and while breastfeeding, for teenagers who are still growing, with a lot of training and when medication belongs with set meals. Then the question belongs with a doctor or a clinical nutrition service.
Our suggestion and what Rhythmus does with it
We think three meals with 4 to 5 hours in between is a sensible starting point. The gut gets its fasting phase, hunger is allowed to come back, and snacks out of boredom tend to drop away. It isn't backed as a rule. If four meals or an afternoon snack work well for you, you're doing nothing wrong.
Under Nutrition there's a timer that counts up from your last meal. It's off until you turn it on, sets no goal and counts no streaks. After a few days it shows how long your gaps are on average. The times stay on your device and are deleted after 14 days.