Lots of us do it: chow down on a sneaky chocolate bar or doughnut to get us through the afternoon. But it looks like the sweet-toothed among us might need to rethink our strategy: new research has found that scoffing sugary snacks doesn't improve mood, and can even make us feel worse.


Scientists in Germany and the UK analysed data from 31 previous studies, involving nearly 1,300 adults, to investigate the effects of sugar on aspects of mood such as anger, alertness, depression, and fatigue.

Previous research has been divided about the psychological effects of sugar - some studies have found improvements; others the complete opposite.

But combining the results from multiple studies, the researchers concluded that sugary treats have no positive effect on mood, regardless of how much is consumed.

In fact, people who consumed sugar tended to feel more tired and less alert in the first hour afterwards.

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"The idea that sugar can improve mood has been widely influential in popular culture, so much so that people all over the world consume sugary drinks to become more alert or combat fatigue," said lead author Dr Konstantinos Mantantzis at Humboldt University of Berlin. "Our findings very clearly indicate that such claims are not substantiated - if anything, sugar will probably make you feel worse."

A report published last year in the National Diet and Nutrition Survey produced by Public Health England based on figures collected from 2014 to 2016 found that many people are eating well over the recommended amount of sugar each day.

According to the study sugar makes up 13.5 per cent of 4 to 10-year-olds', and 14.1 per cent of teenagers' daily calorie intake respectively - almost three times the recommended amount. Adults fared little better with sugar accounting for 11.2 per cent of their daily intake. The main culprits for all ages were soft drinks, sugary cereal, and sweets and chocolate.

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The official recommendation from the government is to limit sugar consumption to no more than 5 per cent - around 30g or seven cubes of sugar per day for adults, 25g for 11 to 16 year-olds and 20g to five to eleven-year-olds.

With excessive sugar intake being linked to health issues including obesity, tooth decay, and type 2 diabetes, the authors hope that their results will discourage people from using sugar as a quick "fuel refill".

"We hope that our findings will go a long way to dispel the myth of the 'sugar rush' and inform public health policies to decrease sugar consumption," said co-author Prof Elizabeth Maylor at the University of Warwick.


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James Lloyd
James LloydStaff writer, BBC Science Focus

James is staff writer at BBC Science Focus magazine. He especially enjoys writing about wellbeing and psychology.