If looking to lose weight longer time with constant intensity is a better way to go. I'd never look to be at 100% intensity. 100% is a number for safety reasons, and it should be 220-age in bpm. At 23 that would be 197 bpm! No one in their right mind would ever advise you to shoot for that. Over that your risk induced arythmia and a possible infarction. If you want to get that scientific with it get a heartrate monitor and shoot for like 160-170bpm. I've found that constant load over a long period is best for weight loss, FYI.

Pills breaking down to powder seems like they weren't pressed under enough force, or didn't have enough binders in them. If they are from an underground lab they might still be legit. If they are supposedly pharmaceutical grade I'd say bunk is more likely.