the only variable I would interject in the need for foods wtih high vitamin content
since this would facilitate a low calorie diet even further with more effect and safety
Thats not really true though. Protein for example requires more calories to burn and can suppress appetite. Sugar requires fewer to burn and doesn't have the same appetite suppressant abilities. 1000 calories of protein is totally different than 1000 calories from sugar in regards to how your body responds to them.
As for yogurt, one of the reasons it (and other dairy products) supposedly works for weight loss is because of something called calcitrol. Calcitrol is released when blood levels of calcium are low and it plays a role in fat storage. Large amounts of calcium can lower calcitrol levels. But like others have said this has come under scrutiny and it isn't exactly taken at face value yet. FTR, the original study on dairy & weight loss had nothing to do with weight loss, it was about blood pressure. They just found by accident that people lost 11 pounds in a year by eating more dairy and that is where it started.
I remember the name: Lite-n-Fit or something along those lines. Sugar (added) free. And no fat. Its decent for a snack but expensive and not many calories (which could be good or bad).