Memory: Overweight Young Adults Have Poorer Recollection

The University of Cambridge conducted a study that showed a link between a high BMI (body mass index) and poorer episodic memory among overweight young adults. Episodic memory is the ability to recall past events, a skill many of us use in day-to-day life and conversation.

The study, although small, showed that among 18 to 35 year olds, body weight may influence the structure and function of the brain and its cognitive abilities. It was conducted with 50 participants with BMIs between 18 and 51 (a BMI of 18-25 is healthy, 25-30 is overweight, and 30+ is obese), and had them take a memory test, according to a news release. 

The test, known as the "Treasure-Hunt Task," consisted of the participants hiding items around "complex scenes" and backdrops. Then, they were asked to remember what they had hidden and where they had hidden those items. Overall among the participants, as BMI increased, recollection decreased.

"We're not saying that overweight people are necessarily more forgetful, but if these results are generalizable to memory in everyday life, then it could be that overweight people are less able to vividly relive details of past events - such as their past meals," Dr. Lucy Cheke, the lead author, said. "Research on the role of memory in eating suggests that this might impair their ability to use memory to help regulate consumption. In other words, it is possible that becoming overweight may make it harder to keep track of what and how much you have eaten, potentially making you more likely to overeat." 

In the UK, where the study was conducted, about 60 percent of adults are overweight or obese - a statistic that is on pace to be at 70 percent by 2034. Obesity, which can increase the risks for several health problems, is experienced by men and women all around the world, with several countries having high obesity numbers, according to World Obesity.

The research team believes that the results, which are supported by increasing evidence of a link between overeating and memory, suggest that the structural and functional brain changes found in those with higher BMIs may also be coupled with a reduced ability to retrieve memories - or to even form them in the first place.

"Increasingly, we're beginning to see that memory - especially episodic memory, the kind where you mentally relive a past event - is also important," Cheke said. "How vividly we remember a recent meal, for example today's lunch, can make a difference to how hungry we feel and how much we are likely to reach out for that tasty chocolate bar later on." 

The researchers, understanding that this study involved a small sample, warn that further research is necessary. Cheke says that it is, however, quite possible that being overweight could make it more difficult to keep track of what you've eaten, which could, in turn, result in more overeating.

Dr. Jon Simons, a coauthor, added that recognizing the psychological parts of overeating can allow us to understand obesity better, and could also lead to potential better ways to combat it. The team admits that overeating and obesity leading to poorer memory is concerning because of the health consequences - like poor appetite regulation - that it can cause.

"Understanding what drives our consumption and how we instinctively regulate our eating [behavior] is becoming more and more important given the rise of obesity in society," Cheke said. "We know that to some extent hunger and satiety are driven by the balance of hormones in our bodies and brains, but psychological factors also play an important role - we tend to eat more when distracted by television or working, and perhaps to 'comfort eat' when we are sad, for example."

The findings were published in The Quarterly Journal of Experimental Psychology.

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