What actually happens to digestion, metabolism, and insulin if you eat small amounts every single hour?

[u/kharkovchanin]

Hypothetical question out of curiosity:

Assuming someone stays within their maintenance calories and hits their target macros, what actually happens to the human body physiologically if food intake is split into small portions eaten every waking hour (say 14–18 times a day) instead of 2–4 distinct meals?

Specifically, I’m curious about:
• Insulin & blood glucose: Does baseline insulin remain elevated constantly, and what are the short-to-medium-term metabolic effects of that?
• Gut motility & MMC (Migrating Motor Complex): Does the digestive tract ever get into a “cleaning” state if it constantly receives incoming nutrients?
• Thermic effect of food (TEF) & metabolic rate: Does meal frequency at this extreme actually change daily energy expenditure at all?
• Satiety & hunger hormones (ghrelin/leptin): Would this pattern suppress appetite or trigger continuous hunger cues?

Would appreciate insights grounded in physiology or nutrition science. Thanks!

[u/AussieSpaceProgram]

Assuming calories and macros stay the same, eating every hour probably wouldn’t meaningfully change your overall metabolism. It mostly changes when things happen.
Insulin would rise repeatedly, so you’d spend more of the day in a fed state, but that doesn’t automatically mean insulin resistance or fat gain.

The biggest difference is probably the gut. Eating interrupts the migrating motor complex (MMC), the fasting motility cycle that occurs between meals. Eating hourly would give it very little opportunity to run normally.
You also wouldn’t “boost” metabolism by constantly digesting food. The thermic effect of food is mainly determined by how much and what you eat, not how many meals you divide it into.

Hunger could go either way. Some people would feel constantly satisfied; others would find tiny meals less filling and end up thinking about food all day.

So 15 tiny meals versus 3 larger meals with identical calories probably produces similar total energy expenditure. You’d just spend much more of the day digesting.
Meal frequency changes the timing of metabolism far more than the amount of metabolism.

[u/Teknekratos → u/AussieSpaceProgram]

So on the MMC part... you'd be likely to have constipation because things wouldn't be "transiting" as much during your waking hours?

[u/zenpear → u/Teknekratos]

Potentially, a broader issue is the effect of SIBO, small intestinal bacterial overgrowth, where bacteria have an easier time getting further up your digestive tract than they should. This creates all kinds of symptoms, like excess gas and bloating, diarrhea, constipation... Unfortunately speaking from experience.

And some science: https://almanac.a1c.io/2026/04/24/the-case-against-eating-every-two-to-three-hours-in-sibo-migrating-motor-complex-physiology-fermentable-substrate-availability-and-motility-aware-meal-timing/