For most people, losing muscle mass as they get older is as natural as going gray. But unlike the silver streak in your hair, reduced strength and muscle mass may signal a dangerous risk—especially if you’re carrying extra body fat.

Background: We’ve long known that loss of muscle mass (a condition known as sarcopenia) is bad for our health, increasing our risk for falls and a loss of physical independence. It’s also widely known that being overweight or obese sets us up to develop heart disease, diabetes and other chronic ailments.

When it comes to brain health, research has also shown that sarcopenia and obesity are independently linked to cognitive impairment. Exception: In people over age 70, extra body weight seems to protect against dementia, for reasons that aren’t fully understood.

With this evidence in hand, researchers wanted to learn how the combination of sarcopenia and obesity affects one’s risk for various forms of dementia, including Alzheimer disease.

To study this question, researchers took precise body measurements and performed a thorough cognitive assessment on 353 adults, with an average age of 69. The researchers then determined which of the participants had sarcopenia and were also obese based on their percentage of body fat mass—a condition known as sarcopenic obesity or “skinny fat.” Interestingly, the “skinny” term comes into play because people with sarcopenic obesity tend to look less overweight than those who are simply obese.

In analyzing the data, researchers had to contend with some tricky definitions that are used for both sarcopenia and obesity. Traditionally, sarcopenia has been defined as low muscle mass. Now, some experts also include low muscle function in the definition—as determined, for example, by grip strength. Obesity, too, has been defined various ways. The conventional definition is tied to body mass index (BMI), which is the ratio of a person’s weight-to-height…or it can be defined based on the percentage of body fat.

Study results: Adults who could be described as “skinny fat”—that is, they had sarcopenia, defined by the combination of low muscle mass and low muscle strength, along with a high percentage of body fat—were the most likely to have lower cognitive function. The combination of those features was more strongly linked to cognitive decline, followed by sarcopenia alone and then obesity alone.

Takeaway: Maintaining muscle strength while preventing excess body fat may help protect your cognitive ability as you get older.

If you want to build muscle strength, read here for simple ways to get started. It’s easier than you think!