The Western Pattern Diet (WPD) or also known as the Standard American Diet (SAD) is a modern-day style diet that mostly contains high amounts of processed foods, red meat, high-fat dairy products, high-sugar foods, and pre-packaged foods, that increase the risk of chronic illness. Now, a new study shows that eating a western diet may be messing with the brain function.
A team of researchers from Macquarie University and Griffith University in Australia, the University of Sussex in the United Kingdom, and Yale University and American University in the United States has found that eating highly processed foods like junk foods, which are part of the western diet, could impair the part of the brain tied to self-control, which can induce overeating.
The research demonstrates that a WS-diet can rapidly impair appetitive control in humans—an effect that could promote overeating in consumers of a WS-diet. Image Credit: Martin Rettenberger / Shutterstock
In the study published in the journal Royal Society Open Science, the team has shown that in as little as one week, eating a western diet can significantly alter brain function, with the participants of the study doing worse on learning and memory tests. Further, the Western diet was tied to overeating and craving for sugary treats after consuming a regular meal.
To arrive at their findings, the researchers recruited 110 students between the ages of 20 and 25 at an Australia university. All the students had a healthy weight and consumed a healthier-than-average diet. They were divided into two groups – the western-style diet and the control group.
For the western-style diet group, they were given a breakfast that consists of a toasted sandwich and a milkshake, which is high in fat and sugar. They were instructed to eat this breakfast, and between the second and seventh day, they were asked to eat two Belgian waffles for four days and eat the main meal and a dessert or drink from a fast-food chain on the other two days.
On the other hand, the control group was provided a low-fat, low-sugar milkshake, and a toasted sandwich on the first day. For the rest of the study period, they were asked to consume their regular diet. Both groups were asked to take tests, including the wanting and liking test, and the Hopkins verbal learning test of learning and memory skills.
The wanting and liking test involved a wide range of snacks, while the respondents were asked to rate how much they wanted to eat them. The researchers also asked the respondents to eat the food and report how much they liked the food items.
Further, the researchers asked the participants to keep a diary of their food intake, and they collected measurements of cholesterol and blood sugar levels.
Changes in the brain
The researchers of the study found that eating a high-fat, high sugar diet even for just a week may impact the part of the brain called the hippocampus, which is responsible for emotions, learning, memory, and motivation.
In the study, the team found that even if a person is slim and healthy, eating a western diet for a week has impacted brain function, making it difficult for people to control their appetites. Also, it turns out, palatable food such as sweets, snacks, and chocolates become more desirable when they’re full. As a result, people find it hard to resist overeating.
The scientists say that the more desirable the participants find the palatable food when they’re already full, while in the western-style diet, the more impaired they were on the hippocampal function test.
Also, the western diet group performed worse on learning and memory tests after a week, compared to the control group who had their normal diet.
Interestingly, when the participants repeated the tests three weeks later after the participants returned to their normal dietary eating patterns, their abilities returned to normal. The findings of the study suggest that though there are changes in the brain related to eating a western diet, the damage can be reversed once the person eats a well-balanced diet.
The researchers emphasize the importance of eating a well-balanced diet, and that highly processed, high-fat, and high-sugar foods can negatively impact a part of the brain that is responsible for self-control. That explains why when people eat fast food, sugary treats, and highly processed food, they can’t seem to control their appetite, and they tend to overeat.
Stevenson, R., Francis, H., Attuquayefio, T., Gupta, D., Yeomans, M., Oaten, M., and Davidson, T. (2020). Hippocampal-dependent appetitive control is impaired by experimental exposure to a Western-style diet. Royal Society Open Science. https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.191338