Researchers in Australia have found that a high-fat, high-sugar ‘junk food’ diet can change the brain and reduce your appetite control. A team from Macquarie University and Griffith University in Australia determined that study participants scored worse on memory tests and experienced a greater desire to eat junk food after indulging in a high-fat, high-sugar diet for a week. The details of the study have been published in Royal Society Open Science.
For the study, the researchers recruited 110 people in their twenties that were lean and self-reported fairly healthy diets. During the experiment, they were all subjected to tests that assessed their cognitive skills and everyday memory. They also participated in a “wanting and liking test” that assessed their cravings and appetite.
For the duration of the study, half of the participants were told to eat their normal diet for a week, while the other half were instructed to eat a high-fat, high-sugar diet that included two Belgian waffles at least four times and two fast food meals on at least two occasions. On the first day and the last day, participants were given a toasted sandwich and a milkshake in the lab. By the end of the month, eight people had dropped out, leaving a sample of 102 participants.
The tests showed that those who consumed a high-fat, high-sugar diet declined in cognitive skills and everyday memory. They also showed that the high-fat, high-sugar diet resulted in increased cravings for junk foods and a bigger appetite, despite consuming a similar number of calories. Three weeks after returning to their normal diets, when the group returned for follow-up testing, the differences had disappeared.
The results appear to show briefly impaired function of the hippocampus, a region of the brain that supports memory and helps to regulate appetite. Impairment in this region could result in a greater desire to eat junk food, even if the person is full. Over the long term, a high-fat, high-sugar diet contributes to obesity and diabetes, both of which have been linked to declines in brain performance.