Overeating makes it harder for your hippocampus to recall your most recent meal
My kids have been taught that at meal time, they need to “listen to their tummies,” and know when they feel full or not. Our goal is that the kids are aware of what they’re eating and don’t try to compulsively clear their plates, although sometimes their stomachs become miraculously empty if dessert is brought up after they’ve eaten. Hopefully by declaring that they’re sated, the kids are taking note of the meal for themselves as well, because it turns out that memory may be intertwined in our appetite in more ways than one.
One of the key structures in the brain that helps process memory is the hippocampus. Among other duties, the hippocampus helps regulate the creation and retrieval of new memories. If its impaired at all, it may be harder to keep track of recent information, such as where you placed your keys 10 minutes ago. In mice with hippocampal damage, researchers have noticed that this forgetfulness seems to be applicable to appetites as well. The mice didn’t forget where they left something, but forget when they’d last eaten. Unlike the control mice, the mice with impairments to their hippocampus repeatedly picked up food and nibbling before putting it down, as they weren’t sure if it was time to eat yet or not.
In humans, this relationship between appetite and the hippocampus reveals symptoms surrounding memory. Multiple studies of spatial, item and temporal memory found correlations between obesity and poorer memories, as well as signs of premature aging in the brain. The cause and effect is still a bit unclear though, as high sugar diets that lead to obesity may play a factor in degrading the hippocampus, which then might cycle into more unnecessary eating. As such, simply paying attention to your meals, versus eating while otherwise distracted, may make more of an impression, and therefore let you avoid acting like the continually snacking mice. Being aware of our meals may help you remember when you’ve already eaten, as well as where you left your keys.
Source: Another Reason to Eat Well: Your Brain Will Thank You by Alan Yu, KQED Future of You