From what I've seen, a natural would need more like 10-12 weeks to drop that many % points if everything went right, but you might get 5-6% leaner. If you can't find Bronkaid, you could also use Primatene tablets. It's a minor change (Sulfate vs. HCL) and you'll have to 2 Primatene vs. 1 Bronkaid, but there than that, the average cost is close enough.