Stop and step and spin classes and start training like an athlete. Best thing you can do is get in the weight room and start building strength. Diet melts fat. Training builds lean muscle. Both have their place, but for fat loss, proper diet is all. Start slow, your gym probably has personal trainers that will help get you started with the weights. They also will recommend "cardio." Ignore that recommendation.

When I was training for the Boston Marathon Jimmy Fund Walk (26.2 miles, finished it in about 7 hours) I bet I walked more than any 3 people on this board and my weight never got much below 158. Note: I started at 202 lbs, and dropped to about 160 doing light dumbbell workouts and being LC-ish. After the walk, I hung up my New Balances and started lifting weights and watching carbs carefully and dropped 15 pounds of fat while adding lean muscle mass. I have stabilized at 149-150 and 9% body fat.