I have been drinking a healthy fruit and yogurt smoothie everyday and have been losing weight. I've been using plain non-fat Greek yogurt because it has more protein than regular yogurt. It also doesn't have any sugar. SparkPeople has a lot of great smoothie recipes that I have been trying. I usually drink one before I work out and it gives me energy.
It's also a great way to get in fruits and veggies servings. (You can add spinach to the smoothies, you can't taste it but get great health benefits).