Question: How might my muscle mass and bone density change as I get healthier, and how will that affect my weight?
Answer: As you begin to exercise you want to focus on maintaining the muscle mass and increasing the strength. Under the age of 30, you might be able to build muscle mass and bone mass, but over the age of 30 we gradually start to lose both muscle mass and bone mass. So it is important to strength train. And you definitely want to be able to do that once or twice a week at the minimum.
As far as weight loss goes, it's awful hard to gain muscle mass while you're losing weight and we don't see that a lot. So make sure that you're focusing on your strength training more for maintaining that muscle mass and focus on the cardio exercise for your weight loss.