The way we’ve come to understand diabetes may be changing. According to a new study published in The FASEB Journal, you don’t have to be overweight to develop type 2 diabetes. In fact, the study explains that the condition may be caused more by what you eat instead of how much.

During the study, researchers compared how two people’s bodies broke down a fast food meal. One of the participants was lean, and the other was overweight. Researchers found that it didn’t matter how much the participants weighed–both of their bodies broke down the meal in the same way.

The study suggests that the type of bacteria in your stomach that breaks down food plays an important role in the development of diabetes. Sometimes, this factor is genetic. However, it is also possible for us to change the type of type of bacteria that lives in our guts. According to a study published in the journal Nature foods such as diet sodas and artificial sweeteners may alter the microbes in our stomachs in a way that increases our risk of developing glucose intolerance and type 2 diabetes.

What should you eat to prevent this from happening? The American Diabetes Association recommends a well-balanced diet that includes all major food groups. Fresh fruits, vegetables, and whole grains should be pantry staples. For protein, the ADA recommends choosing lean cuts of meat, such as chicken or turkey, in addition to fresh fish, beans, and lentils. The ADA also suggests limiting sugary or processed foods, such as candy, cookies, potato chips, and sodas.

The takeaway: Being overweight does increase your chances of developing type 2 diabetes, but an unhealthy diet may also play an important role, even if you’re at a healthy weight.

Photo courtesy of Marshall Astor on Flickr