Feeling full, hunger and appetite: why do we overeat?

Essen trotz Sättigungsgefühl?

Eating even though you already feel full – sound familiar? The fact that we often ignore the signals telling us we're full is partly to do with our genetic material. How can we manage to enjoy a balanced diet despite this?

Our digestive organs aren't alone in deciding whether we're hungry or full. Other factors, such as genetic predisposition, gender, age and activity also play a role in the complex processes taking place in our body. And that’s not all: in an environment where everything is available all the time and the temptation to eat could hardly be greater, we actually have to go ‘against human nature’, at least if we want to lose weight. Because the body doggedly defends its reserves of fat. Why does it do this?

Reserves of fat are synonymous with survival

“This is probably due to evolution, and specifically to the fact that our ancestors had better chances of survival in the dim and distant past if they were able to really eat their fill whenever they could," says Prof. Langhans of ETH Zurich. He has been studying the mechanisms of hunger and satiety for decades. “Preventing undernutrition and starvation was relevant for survival. From a biological viewpoint, being overweight was hardly a disadvantage.”

This also explains why we eat too much – even when we already feel full and know very well that gorging ourselves isn't good for our health. And more often than not we eat before we actually feel hungry. Simply because we have an appetite. Why does that appetite meddle with our feelings of hunger and fullness?

Appetite as an important signal

Appetite is essentially a very good helper. For example, once we’ve tasted a food that doesn’t agree with us, we rarely have an appetite for it again. It protects us from foods that are bad for us and makes us want to eat things that are good for us – if we listen to it correctly.

Appetite is very important. Like drugs, alcohol, sex, etc., good, tasty food activates the reward system in the brain. Nature intended it to be that way – if eating were a masochistic exer­cise, we would no doubt have long since become extinct.

Reading the body’s signals correctly becomes more and more difficult, the bigger the fat reserves we already have and the more abundant the lives we live. All of which makes it even harder to lose weight.

How to lose weight nevertheless

Thousands of books have been written about how to permanently lose weight. But people on diets often tend to put on even more weight. Prof. Langhans’s recommendation, on the other hand, may sound astonishingly simple, but it hits the nail on the head:

Eat mindfully and enjoy eating, but be sensible about it and get lots of exercise. That’s pretty much all you can do. As a society, we should take steps to ensure that as many people as possible are able to do just that despite the temptations all around us.

So, to achieve this, we would need to learn to get the right balance between our hunger and fullness cues. Is that possible? “Yes and no – we can learn to eat slowly and to savour what we’re eating. Strictly forbidding ourselves to do something doesn’t help, because sooner or later it will inevitably lead to the collapse of our self-imposed control,” explains Langhans. So he urges us to do something that actually sounds logical: develop a sense of what constitutes a healthy quantity and a healthy balance.

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