There are plenty of shakes, powders and other drinks on the market for use by dieters looking to lose weight. They can help you shed some pounds if you follow the main rule of dieting: if you burn more calories than you eat, the weight will come off.
If the shake you drink helps you cut down on calories, then you'll lose weight. The problem is that shakes are digested and absorbed more quickly than whole foods.
Drinking 200 calories will leave you hungrier a lot quicker than eating 200 calories worth of whole food. A better alternative is eating whole foods that are low in calories and will keep you full such as fruits and vegetables.