Your resting HR is elevated because you are overweight and out of shape. Your heart is having to work much harder than it should largely due to those circumstances. I dont mean that to sound like a personal attack just stating the facts. That alone should keep you motivated to stay on track. I would be very careful with the clen as well knowing this. If it were me I would drop it altogether and lose it through diet and cardio alone. That said, the 120-135 range should still work quite well for you, no need to jack it up faster than that. I would chart that resting HR and see how much it drop as you shed some of these unwanted lbs.