Your statement must be less vague if you are determined to change your diet. You should have a measurable statement, such as one that includes your number of pounds you hope to lose. You should also give a set end date, not just three months. Also, add how you are going to change your diet. Are you going to stop eating less junk food? Are you going to reduce food altogether? Or are you going to start eating veggies?
I hope I helped! :)