Help me figure out my cat's behaviour

[Ladyof2025]

I have a 10-year-old neutered male cat. I keep a tin of dry cat food in a cupboard in my bedroom in case he gets peckish late at night or early in the morning before I come downstairs.

Now to the puzzling behaviour: if I go straight to bed he just comes to bed with me and goes to sleep. But if I give him a handful of dry cat food from the tin, which I lay out on top of a chest of drawers, he will eat roughly half and then leave the room and go out of the house via his cat flap and disappear for an hour or more. I go to sleep and then when I wake up he's on my bed.

I have tried this over and over and over again to test that he always does it, and he always does: he never eats all of the biscuits I give him, only ever half, and he never eats some biscuits and then comes to bed, he always always eats half and then leaves the building.

I'm trying to work out what evolutionary or instinctive thing is driving this behaviour in him and wondered if anybody has noticed the same sort of thing in their cat, or who at least has some kind of explanation.

Just because cat 😄lol

Is he outside for long ? Perhaps he's going out for a drink out of a puddle
( despite the fact that he , I am sure , will have plenty of water in his bowl. )
Perhaps he want to poo after eating before going to bed.

Or just because cat .

Perhaps I should have been a bit clearer. He eats about half of the biscuits, and then immediately jumps down and goes out. I don't think that if it was for a poo he would need to go instantly.

And yes of course he has a bowl of water available at all times. Luckily I have a wash basin with mains cold water in my bedroom.

I think dried food can give cats a burst of energy similar to humans having carbs so you've basically "woken" him up (dreamies are equivalent to sugar). What a thoughtful master you have that he leaves you in peace while he marches around the territory until the excess energy has dissipated.

As for only half, perhaps you offered the equivalent of two wafer thin mints and he couldn't possibly eat two in one go, he'd POP!

Or as pp suggested and he needs a dirty rain puddle to wash them down with. Or the blood of a thousand gnats 😬

I'd say it's because cats only really hang around for the food. If they've had the food they bugger off.
They never eat all the food as they are caching animals.

I reckon it’s the calories kicking in. We just had our beloved cat pts after a struggle with diabetes. While he was poorly we had to take a serious look at what we were feeding him, and discovered 90% of them are full of sugar, carb and other things that are not healthy. Dry food was the worst.