Posted on Jun 08, 2020, 6 p.m.
Maintaining a diet that is full of high fat and highly processed junk foods that are filled with added sugars, such as the typical Western diet, has been found to impair brain function and lead to overeating in as little as one week.
The typical Western diet has previously been connected to a number of health issues such as obesity, cardiovascular disease, and a lower sperm count in men. A recent study from researchers from the UK, USA, and Australia suggest that they have identified why changing from the typical Western diet is so difficult- it disrupts proper function of the hippocampus which is important to memory and regulation of food intake.
When otherwise healthy young adults followed the typical Western diet for one week they were found to perform worse on memory testing as well as craving more junk foods, even after having consumed a full meal.
"After a week on a western-style diet, palatable food such as snacks and chocolate becomes more desirable when you are full," study author Richard Stevenson, a professor of psychology at Macquarie University in Sydney, told The Guardian. "This will make it harder to resist, leading you to eat more, which in turn generates more damage to the hippocampus and a vicious cycle of overeating."
According to Stevenson a properly functioning hippocampus blocks memories related to food when we are full so we are not as tempted to snack, but when impaired food becomes more appealing as memories related to it flood in.
This study involved 110 lean and healthy students between the ages of 20-23 who were divided into 2 groups: one consuming their normal diet and the other consuming a typical Western diet full of fast foods for one week while keeping a food diary, as well as providing receipts and photographs of their food intake.
Participants consumed breakfast in the lab at the beginning as well as at the end of the week. Before and after their meals the participants took a word memory test and were asked to rate how much they wanted to consume 6 foods which included sugary cereals; and after eating each sample they also indicated how much they enjoyed the item and if they could consume more of it.
"Across these pre- and post-meal tests, wanting ratings declined far more than ratings of taste liking," the researchers concluded. "This manifestation of appetitive control — that is the expectation that food is less desirable than it actually tastes — changed in participants following the Western-style dietary intervention.”
Those on the typical Western diet reported finding the samples more appealing even when they were already full, and they were found to do worse on their testing than they did on the other tests. Throughout the next 3 weeks after their diets returned to normal the group that was on the typical Western diet showed results that resembled the control group. Findings suggest that maintaining a healthy well balanced diet may help to reverse some hippocampal damage related to food intake.
Findings support others that suggest a link between hippocampal function and junk food as first demonstrated in animal research. The researchers suggest that more studies are needed to strengthen the links, but that these findings "should be a worrying finding for everyone," and they can envision public health officials someday calling for restrictions on processed junk food in the same way they have done for tobacco.
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