I have used SlimFast (SF) with this. I have never used it in the past, but my thinking was I could use IT as an in-between snack thinking my snacks were old "diet foods". I love how they have those better flavored drinks too. And they really ARE filling as the cans say. The granola bars are especially filling as well. I feel it much better than eating other types of "snacks", but hope it's not contributing too many calories. The idea of using SF sounds great, but I don't know if it's positive or not. Anybody know?