Tammay, there is a newish study that the media keeps hyping somewhat incorrectly but it talks about the effects of whole grains on body weigh. You'd have to wade through the hype to find the details. Whole grains should be part of a healthy, balanced diet.
Initially, it was said the study proved potatoes were evil but that was not the case. The actual study is something to ponder though and has some interesting data.
Here is a NYT article but I'd recommend finding the actual study