A healthy diet and exercise doesn’t only keep your body in shape, it also boosts your brain health by protecting it from cancer. That’s according to a new study published in the journal Neurology, which found that being overweight or obese may increase risk of a type of brain cancer called meningioma.

In the U.S., 69 percent of adults age 20 and up are either overweight or obese, according to the Centers for Disease Control and Prevention. Being overweight is just a step away from being obese, which increases risk of life-threatening diseases, such as heart disease, diabetes, and certain cancers. A 2003 study of over 900,000 people found that, among people aged 50 and older, being overweight or obese accounted for 14 percent and 20 percent of all cancer deaths in men and women, respectively. This risk could be offset by losing as little as 12 pounds with exercise.

Gundula Behrens, study author from the University of Regensburg in Germany, and his colleagues sought to determine the influence weight and physical activity could have on the risk of developing meningioma and glioma — two of the most common primary brain tumors in adults. To do this, they looked at a meta-analysis of 18 previous studies involving more than 6,000 people, half of whom had meningiomas, while the other half had gliomas.

Some of the studies involved comparative analyses between people with brain tumors and their healthier counterparts. The findings revealed overweight people — with a BMI of 25 to 25.9 — were 21 percent more likely to develop meningioma than a healthy weight person, while obese people — with a BMI over 30 — were 54 percent more likely to develop one. However, when looking over all the studies, they found no relationship between excess weight and glioma. Despite occurring at about the same rate (five to eight of every 100,000 people), gliomas tend to come with a worse prognosis.

As you might expect, a high level of physical activity was associated with a decreased risk of meningioma, and those with the highest amount of physical activity were 27 percent less likely to have this type of brain tumor when compared to those who exercised less.

"This is an important finding since there are few known risk factors for meningioma and the ones we do know about are not things a person can change," Behrens said in the press release. "Given the high prevalence of obesity and the unfavorable prognosis for this type of tumor, these findings may be relevant for strategies aimed at reducing the risk of meningioma."

Behrens and his team warned that the analysis does not prove excess weight and lack of physical activity cause brain tumors, but that it only shows a link. They said several biological processes could be responsible, including higher levels of insulin commonly associated with excess weight, which could promote tumor growth.

Sources: Niedermaier T, Behrens G, Schmid D et al. Body mass index, physical activity, and risk of adult meningioma and glioma. Neurology. 2015.

Calle EE, Rodriguez C, Walker-Thurmond K et al. Overweight, obesity, and mortality from cancer in a prospectively studied cohort of U.S. adults. N Engl J Med. 2003.