Same things for me, but I was already "normal" weight, but fixed my lower back pain was... exercising. Back exercises, not just walking. Go to a gym and get a plan made out.

You don't need to become the next hulk. If you sit all day, as you get older you can get away with less and less, at some point you need to start exercising (and not just 1 type, a range), your bones don't just hole up your body on their own, building muscle around them fixes a surprising amount of Aches and pains you get as you age.

Maybe it's just me but I always saw gym people are the crazy bodybuilder people, but in this modern day in age most people need some level of gym (a lot of it you can do at home too with minimal gear).

*Talking to people sedentary lower back pain people.

The alignment of the lower stomach muscles (and them being out of alignment due to weight-related issues) is not talked about enough when it comes to low back pain