I agree that eating correctly is your number one bet.
However, I would also work with your doctor on strengthening exercises. Walking and swimming are also good "easy on the back" ideas.
Increasing fruits and veggies, cutting down on fat intake and certainly eating
smaller portions are a great way to start to lose weight. Unfortunately,
many restaurants in the USA serve large portions and many of us feel guilty leaving food over.
Check with your doctor prior to doing stretching or back exercises because you don't want to overdo it. Healing takes time, diligence and patience.
Good luck!