A diet high in fat and sugar causes changes in gut bacteria, which could lead to significant loss of cognitive function compared to normal diet.
In the research conducted by the Oregon State University, it was concluded that such a diet reduces a person's power to adapt and adjust to changing situations.
Professor Kathy Magnusson said that it was increasingly clear that the gut bacteria or microbiota can communicate with the human brain.
She added that bacteria can release compounds that act as neurotransmitters which stimulate sensory nerves or the immune system and affect a wide range of biological functions.
Talking about the study, Magnusson said that it was done with young animals which ordinarily would have a healthier biological system.
What's often referred to as the western diet or foods that are high in fat, sugars and simple carbohydrates, has been linked to a range of chronic illnesses including the obesity epidemic and an increased incidence of Alzheimer's disease.
The researcher added that this work suggests that fat and sugar alters a person's healthy bacterial systems and that's one of the reasons why such products should not be consumed.
The research is published in Journal Neuroscience.