Help me with my weight issue!?

Ok so I have been trying to lose weight. I start off EVERY MORNING as the same weight EVERYDAY!! I sometime starve myself for the day but it doesnt matter what I do because at the end of the day I gain at least 3 pounds but when I wake up, I'm back at my starting weight. I must excerise with weights and cardio for 2 hours everyday but at the end of the dai I still gain 3+ pounds even if I dont eat that much that day. HELP!!