A new study from Penn State University has found that adults over the age of 65 who lose weight or have weight that goes up and down frequently may experience faster decline in memory and thinking abilities.
The research, published in the journal Obesity, shows that keeping a stable weight could be important for protecting brain health as we age.
The team studied 11 years of data from more than 4,300 older adults who took part in the National Health and Aging Trends Study from 2011 to 2021.
These participants had their weight, waist size, and body mass index (BMI) measured each year, along with memory, orientation, and executive function skills. The researchers used these details to calculate an overall score for cognitive (brain) function.
Dr. Muzi Na, a senior author of the study and professor of nutritional sciences, said the connection was very clear. The more a person’s weight changed from year to year, the faster their brain abilities declined.
Even small fluctuations made a difference. People whose weight changed the least had the slowest decline in thinking ability, while those whose weight changed the most had two to four times the amount of cognitive decline.
In one part of the study, the researchers looked at people who lost at least 5% of their weight.
These individuals also experienced faster memory and thinking decline. The same was true for people whose weight kept going up and down by 5% or more.
On the other hand, people who gained weight but didn’t lose it did not show more decline than those who maintained a steady weight. Still, the researchers stressed that this does not mean gaining weight is good for brain health.
It’s already known that being obese in middle age can raise the risk of brain decline later in life. However, some studies have shown a puzzling link between being overweight in old age and having better brain function. This is sometimes called the “obesity paradox.” Experts believe this could be related to changes in muscle and fat that happen as people grow older.
Dr. Na explained that while their study supports the idea that stable weight is linked to better brain health in older adults, it doesn’t mean people should try to gain weight. Instead, the takeaway message is that sudden or repeated weight loss may be harmful to brain health, especially in later life.
The team also suggests that older adults should monitor their weight at home in a consistent way. This can give a clearer picture of changes than occasional doctor visits.
For example, people can weigh themselves each morning after using the bathroom, before breakfast, and wearing the same clothes or pajamas. If weight changes are noticed, it’s important to talk to a doctor.
Overall, this study shows how important it is to keep track of weight in older age, not just for physical health, but for brain health too.
The study is published in Obesity.
Copyright © 2025 Knowridge Science Report. All rights reserved.
