If you’ve ever had a ‘sugar rush’, then you’ll know sugar can affect your mood – but why and how? Our nutritionist explains.


We typically associate what we eat with our physical health and even appearance, but increasing evidence supports a link between the food on our plate and our mood or emotions. Likewise, how we feel can affect our food choices too – haven’t we all reached for that ‘feel-good’ slice of cake when we’re feeling low? Or perhaps noticed that stress can affect our appetite?

Some of the pleasure we get from eating foods – especially sweet treats like chocolate and cake – comes from associating these foods with the emotions and feelings they trigger. However, the role of food and our mental well-being goes beyond this and is intricately connected to our brain’s reward system, our inbuilt preference for all things sweet and to the two-way conversation that goes on between our gut and our brain, known as the gut-brain axis.

Bowls and spoons full of different types of sugar

What is sugar?

The sugar we are most familiar with is the white stuff, typically derived from plants including sugar cane and sugar beet; this is a simple carbohydrate and is broken down quickly by the body. We all know we should be eating less sugar but it’s important to remember that it’s this added ‘free’ sugar we need to focus on and not the sugar that occurs naturally in foods, like milk and fruit.

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When we eat sugar, we stimulate pathways in the brain that make us feel good. That ‘sugar rush’ feeling is actually a boost of feel-good brain chemicals including opioids and dopamine. It occurs as our blood sugar levels spike, but the effect doesn’t last long – about 20 minutes – and is followed by a rapid drop in blood sugar, which may leave us tired and in need of more sugar to stabilise levels and make us feel good again. Some scientists have likened this response to addiction, however there are mixed views on this and no conclusive opinion to date.

In conjunction with these effects, the health of our gut and the microbes within it also play a critical role in how we feel. There is still much for us to learn in this area but what we do know is that our food choices impact the types of microbes that thrive in our gut and these in turn influence our mood via the gut-brain axis.

Can sugar make me irritable?

Our brains are programmed to see sugar as something we enjoy and want, this is because eating sugar stimulates feel-good endorphins associated with reward, when this wears off we may become irritable, grumpy and perform less well at cognitively demanding tasks.

Why does sugar make me feel sad?

More than half of the calories in our Western diet come from ultra-processed foods. These are rich in sugar, refined carbs and salt. If we regularly eat this type of food, especially sugars, we are more likely to be diagnosed with mood disorders and depressive symptoms. This may be partly because high-sugar diets appear to decrease the production of the feel-good hormone serotonin, and reduces our response to it in the brain, where it influences our mood.

Does too much sugar cause depression?

Eaten regularly, added sugars promote inflammation and overtime this appears to drive changes in feel-good brain chemicals which can lead to depression and to problems with attention and memory. Men appear to be particularly susceptible to these effects.

Lots of yellow dice with a different emotion illustrated on each side with a cartoon face

Does eating sugar lead to anxiety?

The more calorific and sugary the foods we enjoy, potentially the more likely we are to feel anxious, and the longer we continue to consume these foods, the higher our risk of feeling like this is.

Why does sugar make me emotional?

Even for otherwise healthy young people, high levels of sugar in the blood appears to compromise their ability to process emotions.

Can sugar make me feel stressed?

For many of us, being stressed makes us dive for the cookie jar, this is because eating sugary food dampens our stress response. However, reliance on sugar in this way may make you more dependent on it, reduce your ability to manage stress and even make you more stressed in the long run.

Why does sugar cause tiredness?

Added sugar provides empty calories, meaning foods rich in them supply energy but have no other nutritional value. Studies now suggest that rather than these calories from sugar fuelling the body as you might expect, they actually hinder our production of energy and deplete nutrients from the other foods we’ve eaten. This means eating sugary foods may leave you feeling tired and fatigued.

There are a variety of ways in which sugar seems to affect mood – both immediately after eating a sugary snack and as a result of a longer-term high-sugar diet. If you’ve noticed you’re susceptible to mood changes after eating sugar, or if you’re looking to take action to improve your mental well-being, cutting down on refined sugar might be a good place to start.

Close-up of brightly decorated iced doughnuts

Enjoyed this? Now read…

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What affect does sugar have on your mood? Share your experiences in the comments below….

Kerry Torrens BSc. (Hons) PgCert MBANT is a registered nutritionist with a post graduate diploma in personalised nutrition & nutritional therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including BBC Good Food.


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