I always assumed despite the slight laxative effect of coffee, the real reason is most people are just morning poopers and morning coffee drinkers.

I think it's because it pulls water into the intestines, which helps you poop easier.

As it's a diuretic I'd say it pushes water, but yeah.

I noticed years ago while feeding my newborn that she would chug some delicious warm milk and fill up that diaper. Since then I always figured the coffee phenomenon was related.

Drinking plain warm/hot water can trigger the same response so it is arguably not just coffee.

I vary my routine a lot, so I am pretty sure that it is the liquid coffee here that is the trigger. Not just caffeine because I normally use caffeine pills instead.

It's hard to discount other factors but I certainly notice a difference switching from water to coffee.

It's a pretty strong effect for me, but IIRC there are multiple causes, like that it's hot + acidic + caffeinated.

On some days I'm 8-10 times a day coffee drinker and on the same days I turn out to be 4-5 times a day pooper. I suspect there is some connection.

I can drink as much coffee as I want and I experience no laxative effects. But if I eat some chilli peppers next morning I feel like I am going to explode.

Correlation <> causation.

Most people tend to poop around the same each day. Largely because we tent to eat around the same time each day.

Most people tend to drink coffee at the same times each day. Naturally for a bunch of folk one will co-incide with the other, at least some days a week.

The added factor is that most people (who drink coffee) drink multiple times per day, allowing for more correlation opportunities.

But mostly what causes pooping is eating (he says, speculating, with no data to back it up.)

All stimulants cause this, it is well known.