I lost 40 pounds a few years ago simply by cutting my calories. I consumed half of what I would normally eat. If I would normally have a bagel at breakfast, I ate half a bagel. If I was going to have pizza for dinner, I would have 1 slice, instead of the 2 or 3 slices that I would normally eat. It took 3 months, but I lost the weight with no exercise. After I took the weight off, I decided I wanted to eat again because I like it, so now I run 20 miles a week, and have gone back (mostly) to the same level of eating I was at before.
I would suggest that security should be the top priority ahead of everything else.