Eating cheap food can cause irreversible dementia, a study warns.

The research found the normal individual is eating an additional 650 calories daily contrasted with 1970s, which is the equivalent of a burger, soft drink and fries.

Australian National University’s teacher Nicolas Cherbuin and his team discovered strong evidence linking unfortunate dietary habits and practically no physical action to a decrease in brain function, for example, soft drink and fries.

‘People are eating away at their brain with a really bad fast-food diet and little-to-no exercise,’ says professor Cherbuin.

Many people who have dementia and other signs of cognitive dysfunction, including shrinking brains, have increased their risk throughout life by eating too much bad food and not exercising enough,’ he said.

Teacher Cherbuin clarified the most obvious opportunity of preventing brain problems in the future, such as dementia and brain shrinkage, is to eat well and keep active from a young age.

He said: ‘The damage done is pretty much irreversible once a person reaches midlife, so we urge everyone to eat healthy and get in shape as early as possible — preferably in childhood but certainly by early adulthood.

Professor Cherbuin said their research not only links type 2 diabetes and the rapid deterioration of brain function, but also shows a clear association between brain deterioration and unhealthy lifestyle choices.

He said: ‘As a society, we need to stop asking, “do you want fries with that?”

‘The message is simple, but bringing about positive change will be a big challenge. Individuals, parents, medical professionals and governments all have an important role to play.’

The research analysed the outcomes from 200 studies including The Personality and Total Health (PATH) Through Life venture that pursued the brain health and ageing of 7000 people.

It also found that 30 per cent of the world’s adult population are either overweight or obese.

While more than 10 per cent of all adults will suffer from type 2 diabetes by 2030.