If I drink 3 protein shakes a day will I gain weight?

I am a 40 year old woman trying to lose weight, I have been told that more protein you take in the more you lose. I am also drinking the protein hot cocoa drinks from medical weight loss. I walk on the treadmill about 45-60 minutes a day and I lift a little weight but not much. I am not losing the weight that I thought I would lose, is it because I am drinking the shakes? I also only eat like 1200 calories a day. Thank You Tracy