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Eating junk food every day impairs memory and appetite control

Photo by Pez González on Unsplash

Does what you eat change how you think and behave?

New research by psychologists in Australia, the USA and the University of Sussex in the UK shows how eating  ‘junk food’ affects the part of the brain that controls memory and appetite.

In a study conducted in Australia, the research team tested the effect of a ‘Western style’ diet rich in sugar and fat on tests of memory and appetite sensitivity that involve the hippocampus.  This small area of the brain is key for normal memory function, and previous research suggested that the activity of the hippocampus was altered in people who habitually consume a less healthy diet.

The researchers asked lean and fit volunteers, who normally ate a balanced diet, to eat one meal that was high in sugar and saturated fat every day for a week. They could choose between Belgian waffles and a meal from a fast-food restaurant. The fast-food group was compared with other volunteers who continued to eat a healthy balanced diet all week.

At the beginning and end of the week, all the volunteers performed simple hippocampal-dependent tests to assess their memory, learning and appetite control. Everyone was tested again three weeks later when they had returned to their normal diet.

The scientists observed a rapid decline in the fast-food group’s learning and memory abilities, together with a loss of appetite control. When they were re-tested three weeks later, after returning to their usual healthy diet, the volunteers’ memory and appetite had returned to their normal baseline at the start of the study.

Professor Martin Yeomans, who researches appetite and nutrition at the University of Sussex's Sussex Ingestive Behaviour Group helped structure the study. He explains:

“Our new study adds weight to growing evidence that habitual consumption of an unhealthy diet has a knock-on effect on the brain.  This change leads to a vicious cycle which might explain why people find it progressively harder to switch to a healthy diet even when they are aware that their diet is leading to weight gain and consequent health problems.”

The research  paper, Hippocampal dependent appetitive control is impaired by exprimental exposure to a Western-style diet, is published in Royal Society Open Science.

Listen to Prof Yeomans talking abou the work of the Sussex Ingestive Behaviour Group in this episode of the Impacted podcast. 

Last updated: Monday, 24 February 2020