30 in 5

I am new to this site but have used the I phone app for a few months. 8 years ago I lost 70 pounds in a year and a half, in the last 4 years I have gained 40 back. My goal is 30 pounds in 5 months on a 1200 calorie diet. I will achieve this by eating 4-6 small meals a day and 5 hours a week exercise.