Find a gym that can offer a metabolic assessment - we do ours at our Lifetime Fitness. We can do it on a treadmill, spin bike, or our own bike (so I've lugged the trainer up to the second floor along with our single bikes). $50 one-time for mask plus $95 (I think) per test, and you get a report of YOUR heart rate zones along with YOUR percentage of fat burn in each zone. I burn more fat in Z1 than any other, so I have to think about my goals very carefully. Consider also a resting metabolic assessment - this helps you determine your baseline caloric intake, so you can manage the dietary stuff around a personalized value.