Its a great form of exercise to burn fat and if it gets to intense your instructor will let you back off for a little bit. So there is nothing to be scared about.
Your diet and exercise is like they are saying it is probably just muscle and water weight. Stick with it and you will see some results before you know it.
If you are asking if that is a good meal before a workout I would say yes except the milk just because drinking milke before a wokout could make you sick.