You know that maintaining a healthy weight may protect you against a variety of chronic diseases, including heart disease, stroke, type 2 diabetes, and some types of cancer. Now, a recent study in Neurology suggests there’s another reason to maintain a healthy weight: Being overweight in midlife may accelerate aging in the brain, according to the study, which included 1,289 middle-aged and older adults (average age 64).
Individuals with a higher body mass index (BMI) and waist circumference at the start of the study were more likely to have greater thinning in the brain’s cortex region than those with lower body weight, as assessed by an MRI scan six years later. Having a thinner cortex has been linked with an increased risk of Alzheimer’s disease. The more overweight the individual, the greater the average amount of thinning; that was especially true for obese people (BMI of 30 or higher), among whom every unit increase in BMI was associated with a 0.2 millimeter thinner cortex. (For context, the cortex thins between 0.01 and 0.1 millimeter per decade in normal aging adults.)
BMI and waist circumference were associated with cortical thinning even after the researchers controlled for other factors that can affect the brain, including high blood pressure, alcohol use, and smoking.
Keep in mind that this was an observational study, and, as such, it cannot prove that being overweight in midlife accelerates brain aging. Nevertheless, because of the well known health consequences of being overweight or obese, it’s hard to overstate the importance of losing excess pounds if you need to.