Nutritional Psychology: Can a 1-Week Junk Food Diet Change Your Brain and Lead to Overeating?

Researchers are zeroing in on whether high-fat, high-sugar foods can impact our brain, and influence our eating choices. It turns out that they can and do, and the Hippocampus, a major structure within our brain, is one of junk food’s favorite targets.

We were excited when we heard about this recently published study. We knew it belonged in the CNP Diet and Brain Research Category, and would be the perfect flagship study for our first Diet-Mental Health Break (DMHB). CNP’s DMHBs are quick 2-3 animated cartoons that take cutting-edge research studies and turn them into highly palatable (no pun intended) animations that support conceptualization in the field of Nutritional Psychology (NP).

This animated series is designed for inclusion within CNP’s Nutritional Psychology curriculum and can be used by educators, mental health professionals, dietitians, and other interested individuals to develop an understanding of how diet affects mood, behavior, and mental health. This increased understanding can lead to tools to better support our Diet-Mental Health Relationship (DMHR).

The lead author of this study, Dr. Richard Stevenson from Macquarie University in Sydney, Australia, has been investigating the effects of what are called “highly-palatable foods” on a part of our brain called the hippocampus. Investigation in this area had been done before, but this study was only the second to demonstrate whether exposure to a western-style diet actually causes hippocampal impairment (the first study on this topic can be found here).

Study Methodology

Dr. Stevenson’s study included 102 healthy university students, all who regularly ate a healthy, balanced diet. For the duration of the experiment, half of the group ate their regular balanced diet, while the other half ate their balanced diet plus additional portions of junk food each day.

At the end of the week, both groups’ hippocampal functioning was tested to see whether the junk food added to their diet changed their desire for these foods. The hippocampus is the part of our brain that helps us to learn, remember, and control our appetite.

Study Findings

The participants’ desire to eat the highly palatable foods was significantly increased to the point that they continued to eat even after they were full. This study showed that when we eat junk-style foods – foods high in processed sugars and fats – the high-sensory experiences of anticipation, pleasure, and reward are encoded into our memory. This memory influences what we like and want to eat, and how much. It sets us on a path to want and like more highly stimulating junk foods, and to eat more of them. In the end, this study demonstrated that just one week of added junk food significantly impaired the ability to control one’s appetite. Food for thought…

The full research study by Dr. Stevenson and his team, entitled “Hippocampal-dependent appetitive control is impaired by experimental exposure to a Western-style diet,” can be found here. Watch CNP’s animated Diet-Mental Health Break (DMHB) video on this study here.

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