Hi. I was diagnosed with this too and it did not develop into osteoporosis (yet) and got better. I used to be very VERY thin and drank a lot of pop. I am no longer thin (rats) and cut down on the caffeine. My doctor said it is probably related to having less of a worry about my bones. But, that's just my situation. How old are you? How did they diagnose it? Did you do a bone scan? Here's an easy to read article on treating osteopenia. (to prevent full blow osteoporosis). https://www.webmd.com/osteoporosis/guide/osteopenia-treatments-medications#1 In all seriousness, lifestyle things are supposed to really help. Exercise regularly, cut back on salt and caffeine, eat a diet rich in calcium and vitamin D (since you put this on the vitamin D forum, you probably know that), do you like sardines? Eat sardines (nope, not me) and salmon. Give up smoking and drinking.
Then supplements. Calcium and Vitamin D are important. Do you take this? Most adults should get between 1,000 and 1,200 milligrams of calcium and 600 to 800 international units (IU) of vitamin D every day. I would not be surprised if your doctor doesn't recommend extra vitamin D than that amount.
And there are medications that can be prescribed too.
What is your doctor suggesting?