Why We Grasp Instinctively to Junk Food and Not Healthy Food

Why is it so hard to choose healthy nutrition? And why do we almost instinctively get our hands on sweets and junk food? Leentje Vervoort researches these facts on the University of Ghent.

22-02-2016 -  by Kevin Van der Straeten

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Why is it so hard to choose healthy nutrition? And why do we almost instinctively get our hands on sweets and junk food? Leentje Vervoort researches these facts on the University of Ghent. 


Hi Leentje, welcome to our studio.  




Why is it so difficult: if we see a jar full of sweets and some apples, we instinctively grab the sweets and never the apples. Why is that?  


Well, it's because the sweets contain a lot of sugar and sometimes a lot of fat. Chocolate for example contains a lot of sugar and a lot of fat. And our body needs sugar, our body needs fat, to grow, to think, to grow our brains for example. And that's why it's so addictive. That's why our bodies ask for us to take it in.  


Okay, but I can understand that we need it. But I would think at a certain point our body would say: "okay well, now you have enough. Take the apple, because what you need now".  


In the early days, in the beginning of Mankind, fat and sugar were not readily available. So every time we saw it, we took it. To make a kind of reserve of it? Yeah, to make a kind of reserve and we couldn't take the chance of losing it, because when it was past and you never knew when it came back.  


Society has changed in the meantime.  


Yeah, now we have changed. Now sugar and fat is all around us. We have an obesogenic environment, is what we call it. There's a lot of sweets, there's a lot of sugar that is readily available, that you can just buy in the store. And everything that you buy is often very fat and often very sugar-full. That's not a good word, I think, but a lot of sugar in it.  


Yeah, but we understand what you mean.  


Yeah, there's a lot of sugar in it.  


It should be a word, though.  


Yeah, it should be a word, because it says what it has to say. And there are a lot of food items where you don't expect sugar to be in them, yet there is.  


But if you look at the reasons why we eat. There are multiple reasons, I did understand.  


Yeah, we do have to eat because we need food. We need to provide our body with energy. To grow, to run, to work, and that's what we call eating due to homeostatic reasons. We have to make an equilibrium with the energy that we take in and the energy that we spend just by living. And eating for homeostatic reasons is triggered by signals from the body, that warns us in cases of starvation or energy depletion. But starvation isn't something we face daily in our society anymore. No, not anymore, but we do have to replenish our energy levels, so it's not starvation but energy depletion. We need to fill up again with energy. That's one reason to eat. Another one is what we call hedonic eating, and that's triggered not by internal signals of the body but more by external stimuli, for example by the smell of certain food items or by just seeing something...  


Like walking on the market and smelling all the nice flavours and then getting hungry?  


Getting hungry. My example is always being in the cinema and smelling the popcorn, because that's very triggering for me.  


Yeah, that sounds familiar.  


Yeah, you probably have eaten, because when you go to the movies, you have taken it in or you're not hungry, but the smell of popcorn makes you want to eat it. So that's more from the hedonic side. You don't eat it because... You're not eating it because you want the energy, but merely because it gives you pleasure and it's a rewarding thing. And a third type of eating behaviour relates to habits. For example, we learn to eat in a certain environment or we learn to eat at a certain time. For example when finishing school at 4 o clock, it's easy to grab something to eat. Things like that.  


But if you want to start eating more healthily, maybe it's a good idea to change those kinds of habits.  


Yeah, being aware of a habit, and being aware of a bad habit, is a good starting point to change, to get that change. If you know that you're not eating because your body needs it, but because it's just the time of day or because of the fun you have from it, if you get insight on why you eat, you can alter your behaviour.  


So what about emotional eating?  


There are a lot of people who eat emotionally. Some people eat emotionally because they are sad, and they don't recognise the feelings in their bodies as sadness, but they have a certain feeling and they think: "it's hunger. I will eat something and then it will pass." Of course it doesn't pass, but they keep on thinking: "oh, it must be hunger. It must be hunger." And they keep on eating. But otherwise you can also eat emotionally because you think it is fun. For example, eating and partying is very closely connected. So that's also a kind of emotional eating.  


But then it's more about being aware of that kind of habits and then getting insight and reacting on the insights?  


Yeah, the awareness and the insight or the knowledge is the first step towards changing behaviour, towards a healthier eating behaviour. And what about tea, for example? If you're used to drinking tea, with sugar in it, and you then taste tea without sugar: ugh! The first sip is indeed very bitter and you wouldn't like it, but what we learned from the psychology of learning and behaviour, is that when you repeat exposures and repeatedly take your tea with a little less sugar, you become accustomed to the new taste and you start liking it. It should take 10 or 15 tries.  


That's even rather quick.  


That's rather quick. That's also a good one for parents of toddlers to have them eat vegetables, for example. They might not like it the first time, they might not like it the second time...  


But give it fifteen times... Not at the same day  


Not in the same day, not even the same week, but keep on repeating it and it's a well-known and an evidence-based technique on increasing liking in food.   


Okay, back to the jar with the sweets and the apples. How do we make sure we make the right choice, the healthy choice?  


Well, let me first say: you can eat sweets. It's okay to eat sweets. It's part of a good diet, but keep it for special occasions. Don't eat it every day. On Sunday for example. Take a small piece of candy on Sunday.  


But a small piece, you say.  


Yeah small, in moderation. In moderation is always better.  


Not the extra-large...  


Not the extra-large bag of crisps, just the small one. But you can eat sweets, you can eat candy, no problem. But keep it for a special occasion. But when you are there and you want to eat an apple or you want to eat sweets, how can you resist the sweets? Well, there's one rather easy thing to do, is putting the fruit in the basket on your kitchen table, and putting the unhealthy alternatives far away somewhere in the kitchen cupboard in the back. You need a chair to climb, to get it.  


So it's easier to take...?  


It's easier to take the healthy choice. Make it easier for yourself. But most of the time you more easily take the unhealthy choice, because it's easier. Yeah, but you can switch it around yourself a bit. It's indeed taking a cookie for example. To score it is easier than taking an apple, because the apple, you have to peel it and you have to wash your hands afterwards. But you can peel it in advance, for example. So make it also easy to make the healthy choice.  


Okay Leentje, thank you for all those insights.  




And you at home: thank you for watching our show. I hope to see you next week!