I would never use protein shakes as a meal substitute, I tend to take them post gym / rugby training as they can help your recovery time it also stops me snacking on carbs on the way home. There is a lot of well established science behind protein using protein when exercising, it is essential for muscle growth, and 215 calories per serving (based on the brand that I am currently using) I don't think is a vast amount of calories. The most important thing to note is that you have to be careful how much you take as large amount of protein can easily overload your kidneys causing them damage in the long run.
I would never use protein shakes as a meal substitute, I tend to take them post gym / rugby training as they can help your recovery time it also stops me snacking on carbs on the way home. There is a lot of well established science behind protein using protein when exercising, it is essential for muscle growth, and 215 calories per serving (based on the brand that I am currently using) I don't think is a vast amount of calories. The most important thing to note is that you have to be careful how much you take as large amount of protein can easily overload your kidneys causing them damage in the long run.