What is the link between sugar and behaviour in kids?

Now I’m all for calling out an unhealthy food source when it needs to be.

However I also believe we need to be clear on why something is not good for our kids.

Sugar has been one such food source which has caught a lot of flack for causing ALL sorts of issues in children.

In a second we are going to look at the evidence – however for the purpose of this discussion I’m defining sugar as refined simple carbohydrate such as those products made with white sugar and flour.

Also for the purpose of this discussion we are looking purely at behaviour, and whether cutting out sugar (as defined above) will make a measurable difference to your child’s behaviour.


The rationale for this link came from a study published in 1978 showing that children with hyperactivity had worsened behaviour after being given glucose solutions. To date this experiment has not be able to be replicated.

Several studies on sugar and child behaviour have been done since this 1978 study. They have been well controlled for by doing the following;

  1. They manipulated each participants diet so the researchers were sure of the exact amount each child was consuming
  2. They had a placebo in place – meaning some children got additional sugar and others got a non-sugar substance which looked and tasted the same
  3. Those providing observation were blind to which child received what. So teachers, parents, and researchers did not know which children received more sugar, and which received the placebo.

This is ‘double-blind’ and prevents bias from anyone involved in the study.


So why do parents believe sugar affect their child’s behaviour?

Well one key reason is expectation. We have been brought up believing that sugar makes a child hyperactive. So when we feed them something high in sugar we look for unusual behaviour. Running around, having hysterical meltdowns, fighting, or shouting. Anytime we notice our child doing something destructive, loud, or difficult…we go ‘ah sugar’.


But seriously – my kid becomes a crazed bongo ball every time he eats something with sugar in it! I know it is not my imagination!?

And you very much could be correct. Your child might go loopy after eating sugar. Scientifically we know this to be the case. Let’s instead investigate what could be going on.

The first culprit could be excitement. Now excitement could be caused by two factors. First, and most usual, is that high sugar foods are usually served in combination with an event. A birthday party, Christmas, Easter, school fair etc. Whatever the occasion, I imagine it is pretty exciting for a little kid…or any kid for that matter! They get to go on rides, or a bouncy castle, or there might be a clown riling them up even more.

Kids are not quite like adults when they get excited. Children, particularly those under the age of 8 years, find it hard to differentiate emotion, and regulate energy. Basically they’re all over the place. What we may perceive as difficult behaviour, is them feeling excited and not knowing how to channel it. I mean wouldn’t a fun event with lots of yum food excite you too if you were five?

The other part of the excitement equation is the food itself. Now icecream and cake is not an everyday affair (I hope). So for most kids, the idea of being able to eat these foods sends them wild with excitement. Again, controlling excitement is not a strong point of young kids.

What else could be going on?

Exhaustion is another biggie. I was over at a friend’s house the other day, our kids were playing. My daughter was on struggle bus. She was finding it hard sharing, or managing any sort of conflict.

I rolled my eyes at my friend and said “oh we had a family gathering yesterday afternoon, she just can’t handle it”.

My friend nodded “yeah there is just so much sugar at those events – turns my child into a little monster the next day”.

My response? “I doubt sugar had a role in it. More likely that she was running around with her cousins all afternoon and went to bed an hour later than usual!”

We conveniently forget the energy which would have been expended at these events, or the late bedtime…we do remember the food. Even so much as 30 minutes sleep debt can make a huge impact on a child’s ability to cope with everyday processes.


But what about in the moment? I hear you say. Sure they’re tired the next day – but what if it is just that they’ve gone to a run of the mill birthday in a park or to a friend’s house to play and got given candy popcorn?

Next time you go to your kids school assembly, or the local park, without being a creep I want you to observe how the children interact and play. A situation where no food is being served.

The kids shriek and squeal. They wrestle and run away from each other. They will get silly and ignore younger siblings, or go as far as to be a bit cruel to them. They’ll giggle, whisper inappropriate things to each other, or argue over silly things.

Simply having other kids to run around with ramps children up. Plus in order to make it amongst your peers there are social norms you have to follow. Unfortunately sitting quietly and listening to mum is not one of those norms.


Do the kids themselves have a bias?

There have been some interesting experiments done regarding placebo. If someone believes they are being given something, that they think should make them respond in a certain way, will they respond like that even with a fake stimuli?

There are two noteworthy examples of this. The first is with alcohol. If someone believes the liquid they are drinking is alcohol – they will report feeling drunk, and act drunk, even if the beverage was actually completely alcohol free.

Another example is with hayfever. Individuals with an allergy to roses, sneezed when given a fake rose to smell. You might see it yourself if you are allergic to dust or cats. If you went into an attic for example, and assumed it was dusty, you most likely would start sneezing, even if you’d not come into contact with any dust.

Perhaps this is the same with children and sugar? If they are told by an adult enough times that they only get sugar occasionally because it makes their behaviour bad – then they may subconsciously adapt their behaviour when they have sugar.


Finally there is a chance another substance is at play. The original sugar and hyperactivity hypothesis caught wind in relation to children having foods such as chocolate or soda/fizzy/soft drink. Problem is both these also contain caffeine, which is a stimulant. So the question remains is it more that caffeine is messing with their behaviour?


Furthermore I want to leave you with the following thought.

Many of the studies on sugar and hyperactivity in children found quite the opposite. That children fed diets with sugar tended to be more relaxed, and perform better on physical and cognitive tasks. It is hypothesized that this is because of the direct link sugar plays in fuelling the brain. So perhaps we shouldn’t be so tough on sugar.


Resources for further perusal





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