How much weight can i lose doing this for 5 months?

If that's all you eat, your body will go into "starvation mode" by slowing your metabolism and you will start burning calories VERY slowly. Also, it will cause your body to start eating muscle instead of fat to conserve as much energy as possible. I know it's logical to think eating almost nothing will make you lose weight, but there's more than that. Metabolism is what needs to be controlled. Eat enough food to keep your metabolism burning calories throughout the day. It takes calories to burn food. You should eat something at lunch in order to lose weight. Good luck.