Junk food consumption may cause spatial memory loss that worsens as poor-diet days add up, a recent animal study has found.

Rats were fed a diet alternating between foods high in fat and sugar (such as pies, cakes, cookies and potato chips) and their regular, healthy diet. Not only were they significantly less likely to notice when familiar objects had been moved in their environment, but their memory problems worsened progressively the more days a week they had access to junk food. 

“Anything over three days a week of eating [poorly] impacted memory in these animals,” reported senior author Margaret Morris, Ph.D., University of New South Wales, Australia.  

“We all know that a healthy diet with minimal junk food is good for our overall health and performance, but this paper shows that it is critical for optimal brain function as well.”

The problem may originate in the hippocampus, a part of the brain that’s related to finding things and navigating spaces, Morris explained. Her team’s prior research has shown that this region changes physically in relation to diet.

The results also suggest that small dietary changes may make a big difference in cognitive health, the authors wrote. The rats on a five-day-per-week junk food diet were heavier, longer and had greater fat mass than those on the three-day-per-week schedule. 

“We want to live and enjoy life, but we do need to temper it with healthy eating most of the time,” said Morris. “This study certainly confirms this.”

The study was published in Scientific Reports.