You already know being overweight isn’t healthy. It can cause tons of problems, especially later in life. But did you know a study done by the journal Neurobiology of Aging actually took brain scans of overweight and slim people, compared them, and found the overweight people’s brains showed signs of being 10 years older?

Let’s back up. Science proved a long time ago that the white matter in our brain shrinks as we age. This white matter contains connecting branches called axons. These connect neurons together, which is referred to as the “cerebral highway” because there are so many pathways going across your brain where electrical impulses travel as the different parts of your brain communicate.

The Study

Researchers recruited 527 volunteers aged 20 to 87. Each one was classified as either “lean” or “overweight” depending on their body mass. After scanning the brains of all participants, the study authors found that from middle-age onwards, the brains of overweight people tended to shrink more than those in the lean group.

Most of the overweight participants’ brains showed as much shrinkage as lean participants’ brains which were 10 years older.The study’s co-author, Lisa Ronan, explained in a statement that “it isn’t clear why people who are overweight have a greater reduction in the amount of white matter,” adding that “we can only speculate on whether obesity might in some way cause these changes or whether obesity is a consequence of brain changes.”

What Science Shows

Unfortunately, the researchers aren’t sure exactly what causes this effect. They think it may have to do with inflammation. As we get older, we experience higher levels of oxidative stress, which is the production of certain molecules that cause damage to body tissues. Previous studies have shown that this often leads to inflammation, which in turn causes the loss of white matter.

The buildup of fatty tissue causes inflammatory compounds called cytokines to release alongside inflammatory hormones like leptin. Researchers believe this may partially explain the reason behind obesity causing such extreme signs of aging.

Thankfully, despite the loss of white matter, overweight people didn’t appear to have lost any cognitive capabilities — meaning they had no problem thinking like everyone else. They also performed just as well as lean people of the same age on IQ tests.

So if you’re overweight, you may want to start thinking about changing your diet and getting proper exercise. Even without shrinkage of your white matter, there are many other consequences of remaining at a high weight. If you need some help getting started, Lifehack has a great goal-setting program to help motivate you to stick to your goals.