HIIT is good for increasing your metabolism, although I have no idea how it would work with the meds unfortunately, that is a question for your doctor.
If your gym has a prowler that will sort you out, load with weight you can sprint with for 30 seconds maximum and take 15 seconds rest and repeat, use a timer and aim for 6 sets of this, working up to 10 over time, that should start stripping fat off. If not follow the same protocol with hill sprints.
Other than that being in a kcal deficit is a must if you are to lose weight of any kind. Regardless of whether excess kcal are stored as muscle, glycogen, fat or anything else it means you are in a surplus regardless, what is your diet like? Because this would be as crucial as the exercise.