Who hasn’t stumbled upon an ad for some ab exercise contraption that “guarantees a flat stomach!”But does doing a hundred of these crunches really help in burning away belly fat?

According to a recent study published in the Journal of Strength and Conditioning Research, simply performing sit-ups, crunches, and other ab exercises won’t do much to reduce your belly blubber.

One group of study subjects performed ab exercises 5 days a week while the control group did nothing. At the end of 6 weeks, there was no significant change in stomach fat in either group. Everyone was told not to change their diet. In the end, those countless crunches were proven to be ineffective in flattening people’s stomachs.

“Aerobic activity must be a part of the exercise prescription. Crunches and such are great to increase abdominal and core strength, but just performing these alone will not increase caloric expenditure above that which is needed to facilitate sizeable fat loss,” says study researcher John Smith, PhD., HFS, an assistant professor at Texas A&M University-San Antonio.”

So basically, while ab exercises can make your abs look great, the only way to see it is to remove the layer of fat on top of them.