Eli5: Why do we still feel hungry even if we’ve had enough calories for the day?


For example, if I was to drink my daily calorie intake in like smoothies or coffee, why does my stomach still rumble with hunger and feel empty?

What’s the difference between feeling full and calorie requirements?

In: 3

Our bodies are still in caveman mode. They are worried that we won’t have enough food at some point due to a famine, and want us to store as much food as possible as fat so that in case there’s nothing to eat for months, we can use the fact to survive.

That was fantastic back in caveman days. It’s not very good now though when we don’t worry about famines, since we end up just getting fat.

Now, if you have gotten used to eating a large amount of food everyday, your body sort of accepts that as normal. It will take time for your body to adjust.

People confuse appetite and hunger. Appetite is triggered by outside sources, such as images and smells, amd by low blood sugar. Eating strategically to release protien and blood sugar over time can combat this, but very few people actively do this and instead eat foods which break down to glucose rapidly, which causes the body to dump insulin to counteract it which causes a dangerous cycle which can lead to diabetes.

Your hunger-signal is not based on the calorie density of the food in your stomach. We have changed our diet to foodsources with a lot of calories that are taken up more easily. That means to fill our stomach we need more of the food for us to feel full. We then take up the calories but they might not be needed because all of them enter our system at the same time. The excess of nutrients are stored for worse times. Then when we get hungry again because we are low in energy our instinct isn’t to use those reserves if there are foodsources available, they are stored in case there aren’t any sources available.

Burning fuel in your body happens all day at different rates and you cannot really easily anticipate when you’ll need more or less. This is why we have a built in mechanism to always make sure there is enough energy to go around in order to prevent certain organs that use a lot (like the brain) from getting too little

It’s also based on what you eat.

If you consume a healthy amount of protein, it takes longer to digest, keeping you fuller.

If you consume mainly simple carbs, they’re absorbed fast and cause blood sugar to spike. Your body releases insulin to combat the spike, and often it releases too much. Your blood sugar crashes and you get hungry again because your body releases the hunger hormone because it thinks you’re out of gas.