Obese and overweight young adults have worse memories than those who are thin, according to a new study.
Writing in The Quarterly Journal of Experimental Psychology, researchers from the University of Cambridge found that higher body mass index (BMI) is associated with “poorer performance on a test of episodic memory.”
The researchers said that while this study was small in size, other studies have shown that higher body weight affects both brain structure and the ability to perform cognitive tasks well, particularly “decision making, problem solving and emotions.”
According to the Centers for Disease Control and Prevention, 35 percent of Americans are obese and fully two-thirds of Americans are obese or overweight. Those numbers are expected to grow.
"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," said Lucy Cheke. "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."
She added that researchers are noticing that episodic memory, reliving a recent event, is another important factor.
“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," she said.
For the study, the researchers asked 50 participants aged 18 to 35 with varying BMIs to take a kind of memory test that measures episodic memory. The higher the BMI, the lower the scores on the test, researchers found.
The results, they say, could be caused by “structural and functional changes in the brain” among those with a higher BMI.
"We're not saying that overweight people are necessarily more forgetful," said Cheke. "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. 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, becoming overweight could make it harder to keep track of what and how much you have eaten, possibly making you more likely to overeat.