An 18lb weight loss will probably remove the need for a functional flight test since it puts you from being class 2 obesity into being class 1 obesity, see:
Obesity - Wikipedia, the free encyclopedia
If you increased your exercise and reduced your calorie intake down to between 1500 and 1700 per day, and then fine tuned your food intake to give you a weight drop of on average 2lb a week, you could get this sorted in only 9 weeks.
A handy online BMI calculator can be found at
Calculate Your BMI - Standard BMI Calculator