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Why you love unhealthy food

29. February 2016 in

Why can’t cake be healthy? Or broccoli more yummy? There is a painful gap between the treats you are craving for and that rabbit food your doctor wants you to call ‘dinner’.

It makes you wonder: What went wrong with nature? How did it spawn an advanced species that loves exactly the kind of food that is bad for its organism? These are justified questions. Evolution will give some answers.


Sunday brunch vs. prehistoric savannah

Let’s have a brunch. An imaginary brunch (I know, they are probably not your favorite kind of brunch).

Imagine a huge buffet with fluffy buns, cheese, ham, salmon and a fine assortment of cakes. And, yeah, also a bit of salad, back there. Done?

Okay. Now imagine prehistoric savannah: We have some dried up berries behind that hill. Ah, and yeah, there is a famished gazelle calf a few hours south. And a half-rotten bird carcass at your feet. But that has already started to smell…

Trick question: Can you spot the differences?

why you love unhealthy food - savannah vs. buffet


Well, we might not live in prehistoric savannah anymore. However, our bodies and instincts still do. And then you send them to brunch. That cannot work, can it?

Evolution is slow. Very slow. Human bodies and instincts changed with the way our ancestors lived and ate. These transformations, however, took place over the course of millions of years. Even if you just look at the last few centuries, humankind changed its menu pretty radically. From evolution’s point of view, prehistoric savannah guys blinked – and found themselves facing today’s all-you-can-eat buffets. No wonder they are confused!

So, you love unhealthy food because brunches are very different from the prehistoric menu that is enrooted in our genes. Don’t worry if this answer does not really satisfy you yet. It will become clearer when we have a closer look at a few things at our buffet. How about some cheese, bacon and cake?


why you love unhealthy food -  cheese

1. Yummy cheese: Why you love fat

It is no coincidence that some food tastes better to us than other. Much of our preferences have to do with how we grew up and personal (food) experiences we made. However, there are also taste preferences we share as humans. These innate likings have developed through evolution: People who preferred certain kinds of food had better opportunities to survive and procreate. Like that, they passed on their food preferences. One of them has to do with that creamy cheese on our buffet.

Fat things are calorie bombs. You can derive more energy from them than from any other substance. For someone who hunts and collects food in a meagre environment, this is a good thing. Also, fat is great for storing energy for later. Nowadays, you do not want fat you eat become fat on your hips. This trend, however, is pretty recent. Look at Botticellian paintings or, in fact, even Marilyn Monroe!

Fat pads were en vogue for a very long time. And for a good reason: They are not only a reserve for hungry days but also boost your immune system. Famished people often die of infections due to the weakened immune system, not directly of hunger. Fat pads only get dangerous when they grow too heavy for the body and their effect on the immune system backfires. This is quite easy in a world full of cheese buffets. But it was nearly impossible for our active ancestors in that brunch-free world.


why you love unhealthy food - sugar

2. How about some cake? Why you love sugar

What is great about cake? Right: sugar. Our love for sugar is innate and it is most evident in children. Already newborns show signs of content when you feed them a sweet solution. Sour and bitter, however, makes them wrinkle their little noses. Do you remember some sweets you loved as a kid, but which turned out disgustingly sugary once you had grown up? This is because children need a lot more sugar in it until something tastes sweet to them. But what is this love for sugar good for?

Firstly, it seems to have been a pretty effective protection against poison. While a lot of poisonous things taste sour or bitter, only few sweet things contain toxins. Especially for children – who love to stuff everything into their mouth -, this poison protection makes sense. Unfortunately, nowadays, it also makes your offspring have rage fits at the supermarket check-out and act as if your brussel sprouts are going to kill them.

There is another advantage to sugar. It contains a lot of energy that the body can easily use. Well, at least this was an advantage for our prehistoric ancestors. They got a lot of physical activity in an environment with rather little sugar. So it made perfect sense to stuff their faces with anything sweet they could find. For many modern people it is exactly the other way around: We get comparably few physical activity in an environment that has sugar in abundance – just look at that imaginary cake buffet! As a result our body converts the spare sugar to fat pads for worse times. This leads us back to point number one: We only create but never use fat pads in the hunger-free environments many of us live in.


why you love unhealthy food -  bacon

3. Any fried bacon left? Why you love salty and crunchy food

While scientists agree that too much sugar and (especially animal) fat are harmful, salt is somewhat controversial. It seems difficult to prove that high salt intake is dangerous for us. However, at least it is rather evident why you love salt. Your blood needs a certain amount of sodium and chloride that it gets from salty food. You only need to look back at the Middle Ages. Salt was so precious then – it was obviously a lot harder to access back in the days. If you had stumbled over a plate of fried bacon in the prehistoric savannah, binge eating would have totally made sense.

But probably, you love fried bacon not because it is salty but rather because it is crispy. There are several hypotheses why we are into crunchy food. It might even have to do with the fact that we cannot only taste but also hear it. It is also plausible that evolution gave us a liking for fried food. After all, it has played a big part in our development. Once, our ancestors had invented barbecues, they discovered a huge energy source. Especially fried meat – but also cooked vegetables or baked grain – is easier to digest than the raw material. Our bodies can use the energy inside this processed food much easier and quicker. Most likely, this was one of our big evolutionary advantages: While other apes had to use a lot of their energy on digesting raw leaves and fruits, humans had found a rich power source that allowed them to invest more energy in growing those big brains we carry around nowadays.

The problem with fried food today is very similar to the one with sugar and fat. In our modern life, fried treats are not nearly as scarce as they were for our early ancestors. And most of us need a lot less energy than those people who spent their days on the move, looking for the famished gazelle calf a few hours South. For us desk workers and brunch lovers, it is often not such a bad thing to give our stomach some hard-to-process food, such as carrot sticks and wholewheat bread.


4. A third helping? Why we eat even though we are full

With everything we have established by now, it might already be obvious, why you do not stop eating at a brunch once you are full. Would your ancestors have counted calories and stopped after half a piece of cake? No, they would have tried to turn the food abundance of a buffet into some handy fat pads. And they would have been aided by psychology: Just looking at food – even if just on an advertisement – can already produce hormones that make you hungry.


Bad news: Evolution will never be quick enough to either make your body thrive on cake or crave for broccoli. You will have to carry the burden of your prehistoric heritage. However, sometimes knowing the mechanism behind it helps.

And if not, there is always comfort food!



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Susanne Krause

About the Author

Susanne Krause
Researcher and author. As a graduate of psychology and philosophy as well as an experienced journalist, she knows not only where to find the information but also how to put it into words best.

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