Eating A Junk Food Diet Quickly Undermines Your Memory And Self-Control

A new study has found that consuming a Western-style diet rich in junk food can subtly yet rapidly impair brain function in your hippocampus. By no coincidence, this is a brain region associated with memory and appetite regulation. Any impairment of this region's function could result in people experiencing a greater desire to eat junk food even if they are full.

“Junk food may then act to undermine self-control by increasing desire,” the researchers explained in a press release. 

“When we see cake, chocolate or crisps, for example, we remember how nice they are to eat. When we are full the hippocampus normally suppresses these memories, reducing our desire to eat,” they added. “We found that lean healthy young people exposed to one week of a junk food diet developed impaired hippocampal function and relatively greater desire to eat junk food when full.”

Reported in the journal Royal Society Open Science, researchers from Macquarie University and Griffith University in Australia gathered 110 “lean, healthy” people in their twenties. Half simply ate their normal diet for a week, while the other half were fed a so-called “Western-style diet,” including super-sugary cereal, fast-food meals, and Belgian waffles. Before, during, and after the human guinea pigs had eaten these diets, they were all subjected to tests that looked to assess their cognitive skills and everyday memory, as well as a “wanting and liking test” that assessed their cravings and appetite.

The findings showed people on the fatty high-sugar "Western-style diet" had decreased memory and cognitive function just a week after taking up the diet. The specific tests they used pointed towards the hippocampus, which plays a major role in learning and memory, as the possible culprit. The “wanting and liking test” also showed that the people on the Western diet tended to crave more junk food and remained hungry, despite eating a similar number of calories.

Promisingly, however, the “wanting and liking” tests were repeated three weeks later after volunteers returned to their regular eating pattern, showing that cravings and hunger levels had returned to normal. This suggests that the effect of the Western diet on appetite control was only short term and could be promptly reversed. 

This is far from the first piece of research to see how junk food affects your brain. A study released last month showed how sugar influences the brain in ways similar to those seen if you have an addiction. Even after just 12 days of high sugar intake, the researchers could see major changes in the brain's dopamine and opioid systems – just like an addictive drug.