Eating junk food can actually change the brain, spurring symptoms of anxiety and depression if you stop consuming it, according to a new study in mice.
Researchers from the University of Montreal found that mice fed diets high in sugar and fat had different chemical activity in their brains and exhibited more signs of withdrawal if they stopped eating it, compared with those fed more healthy foods.
"The chemicals changed by the diet are associated with depression," study researcher Dr. Stephanie Fulton said in a statement. "A change of diet then causes withdrawal symptoms and a greater sensitivity to stressful situations, launching a vicious cycle of poor eating."
The study, published in the International Journal of Obesity, included mice that were fed a diet low in fat for six weeks (where fat comprised 11 percent of calories in the food), and mice that were fed a diet high in fat for six weeks (where fat comprised 58 percent of calories in the food).
By the end of the study, those fed the high-fat diet experienced an 11 percent increase in waist size (but in mouse terms, this was still not enough to actually cause obesity in the mice). Researchers then analyzed the brains of the mice, as well as their emotions and behaviors, after having been on the diet.
They found that the mice fed the high-fat diet were more anxious at the end of the study, and also had higher levels of the CREB molecule, which is known to play a role in dopamine production (dopamine helps promote feelings of reward).
"CREB is much more activated in the brains of higher-fat diet mice and these mice also have higher levels of corticosterone, a hormone that is associated with stress. This explains both the depression and the negative behaviour cycle," Fulton said in the statement.
"It's interesting that these changes occur before obesity. These findings challenge our understanding of the relationship between diet, the body and the mind," Fulton added.
This is certainly not the first time junk food has been linked to negative effects in the brain. A Neurology study published last year showed a relationship between having high blood amounts of trans fats and decreased performance on brain functioning tests, as well as decreased brain volume.
"It's clear that trans fats are bad -- both for your heart and now, we see, for your brain," the researcher of that study, Dr. Gene Bowman, of Oregon Health & Science University, told HuffPost Food. "So I would recommend that people stay away from all trans fats. If you aren't sure whether something has them, just look at the ingredients; if there's vegetable shortening, partially hydrogenated anything... just put it down. That's the big message here."