I had a Slim Fast-type meal plan, purchased from my surgeon's practice. Didn't starve, snacks were built in, and I was eating something every few hours. Not liquid.
What I'd recommend is drinking A LOT of fluid. Also, chewing sugarfree gum, which I also use when I'm baking Christmas cookies, to keep my mouth busy so I don't eat dough. Sometimes you just gotta chew.
Yeah, I lost 19 pounds pre-op. Last time I dieted. Never again.