The best thing to do is to prepare and cook al your meals yourself. Don't use anything that is prepared because you don't know whats in it. If you'd like to eat a hamburger, thats fine but buy the meat and make it yourself. I used to make my own bread but I honestly have to say that I can not always find the time making home made bread.
Taking care of my mom takes a lot of our time and now and then we ordered a pizza but we do know thats not the healhty way.
I'm on some medication so I gain some weight too. Try your best watching what you eat, thats all you can do.