If you’re like most people, you might react to the title of this article with a hearty “Huh?” What, after all, could losing weight have to do with your memory? Well, recent research is starting to show that although it cannot be said for sure that overeating and obesity cause memory loss and hazy thinking, it can definitely be shown that both are as hard on the brain as they are on the heart and the kidneys.
In a study performed at the Mayo Clinic, patients over 70 who consumed diets containing more than 2,143 calories per day doubled their risk of memory loss and mild cognitive impairment. These conditions are considered possible precursors to Alzheimer’s disease, and indicated a state of mental decline far beyond those expected in people of that age. In comparison, subjects in the same study who ate a more reasonable diet showed no measurable mental decline over the 8-year length of the research.
Another study published in the journal Neurology found a strong association between obesity and the decline of cognitive function in middle-aged subjects, with an average age of 50. Study author Archana Singh-Manoux said, “Obesity, in mid rather than late life, is now an established risk factor for dementia. We looked at people who are obese and also have high blood pressure, high blood sugar and other risk factors called metabolic abnormalities, and found they experienced a faster decline in thinking, reasoning and memory over time.”
During the study, which extended for ten years, the obese subjects’ brains aged 3.8 years more than the brains of subjects who maintained a healthy weight. And the most obese subjects showed a 22.5% faster drop-off in their performance on tests used to measure cognitive functions than those who were not obese.
Losing large amounts of weight improved memory skills
In another study conducted at Kent State University and published in the journal Surgery for Obesity and Related Diseases, subjects being treated for obesity were given gastric bypass surgery. Although a drastic step, this procedure enabled them to lose an average of 50 pounds in as little as 12 weeks. The weight loss was reflected in many expected improvements to the subjects’ overall states of health, but an unexpected result was that those who lost this much weight showed marked improvement in measurable memory and organizational skills. The study authors suggest that similar results would be found in people who lost weight by traditional means, through lower-calorie diets and exercise.
In research published in Human Brain Mapping, neurologist and senior study author Paul Thompson found that the brains of obese subjects contained 8% less brain tissue than subjects at normal weights. The brains of overweight subjects in the same study contained 4% less brain tissue than non-overweight subjects. Thompson says about his findings, “That’s a big loss of tissue and it depletes your cognitive reserves, putting you at much greater risk of Alzheimer’s and other diseases that attack the brain.”
This research is being weighed against the results of other studies, which found that the researchers could predict cognitive impairment as the result of eating a diet high in calories and monounsaturated fats, and (in another study) that there is a strong association between metabolic syndrome and memory loss.
No one is quite sure what the mechanism is that controls this association between obesity and overeating and memory loss, only that such an association seems to exist. Taken together, all of these studies add more reasons to the many we’ve heard already to control our diets and maintain a healthy weight. Doing so may not just help us live long enough to enjoy our sunset years, it may also help us to be able to remember them.