Nutrition - When you eat sugary foods, do you struggle to stop?

People regularly share that once they start eating something sweet it feels impossible to stop. Or that when they try to reduce their sugar intake their tastebuds have other plans. Often they feel ashamed of this, and berate themselves after eating more than they intended to.

But it’s not a lack of willpower driving this.

There are biochemical reasons why sugary foods and drinks are so desirable, and why it can feel so hard to stop after a small taste.

Humans have evolved to love the sweet stuff. This is partly because historically the bitter foods we would find when hunting and gathering were more likely to be poisonous and partly because sugar is rich in energy (calories) and provides fuel that our brain uses (glucose).

For many of us in more recent decades, food is abundant. Yet it wasn’t that long ago that food shortages were a key threat to our survival. In a world where food may be scarce, it makes sense that we would be drawn to, seek out and eat more of the sugary quick energy-fuelling foods. Plus these ‘foods’ weren’t available from a supermarket shelf – they could be hard to get our hands on. Yet, this evolutionary quirk can bite us in the modern world where there is an abundance of food on offer—particularly lots of ultra-processed foods containing highly concentrated sugars.

Sweet foods and drinks give our brain a great big hit of a chemical called dopamine. This activates our brain’s reward system, essentially communicating that this is definitely something we want to experience again. When we consistently overconsume sugar, we are activating this reward system again and again—and so our brain starts to adapt. It’s like we build up a tolerance and you may find yourself desiring more and more to get the same feel-good response.