Hi Buddha! To answer your second question first, YES it's possible to lose a buddha belly! As you lose body fat, the excess fat will all come off - eventually even your trouble spot, which I'm guessing is your belly. But don't give up if it seems like your belly is the LAST place that the weight is coming off! Lots of us lose that horrible trouble fat last of all. I carried my fat in my butt and thighs and thought it would never
go away, but the last 20 pounds came off 100% from those areas.
But for a long time as I was losing weight, I was shaped like a bowling pin.
About heart rates and exercise - I'm not sure what you're asking? Are you wondering why your heart rate is higher in a class than on the treadmill? If that's the case, it's because you're working harder in the class than on the treadmill. Your heart rate is simply an indication of how hard your heart is working to get oxygen to your tissues. I can certainly imagine classes - especially with squats and sprints - that require a lot more exertion than the treadmill. Personally, I have a tough time getting my heart rate up at all on a treadmill unless I'm running or walking very fast on an incline. Even a 4 MPH walk doesn't do much at all for my heart rate, so I don't use it as cardio. Anyway, that's all heart rate is - an indication of how hard you're working at whatever exercise you're doing.
Could your higher heart rate on weekends be due to doing different exercises? Or could you be working harder on weekends because you have more energy than you do after work?
Congrats on the improvement in your heart rate (resting, I assume?) As your heart becomes more conditioned through exercise, don't be surprised if you have to work harder and harder in order to elevate your heart rate. It's a good thing for your heart to become more efficient, but you'll need to increase the intensity of your exercise in order to raise your heart rate into a cardiovascular zone.
It sounds like you're doing great with the exercise - keep up the good work!