Before cancer, I was a reasonably healthy, reasonably active, very stable 135 pounds, meaning I could have stood to lose about 10-15 pounds, but not a really big deal (I am only 5'2''). With cancer treatments, post-treatment side effects, ostomy, and post-ostomy issues, I bounced around like a yo-yo, down to 114, back up to 135, back down to 120, up to 150 (considerably overweight!), and now slowly losing, currently at 147. I have a honking big peri-stomal hernia and way too much fat in the belly, but I am working back to my goal of 120 pounds. It's really tough! I ride a bike for 30 minutes a day during the week and longer on weekends (I usually end up with 5-6 days a week average, as life gets in the way). I eat healthy whenever I can, lots of salads, fruit, and vegetables (I don't have too much trouble with impaction, although it took probably close to a year to move from a post-surgery low-residue basically unhealthy diet to a healthier one). I think the biggest thing was reducing the sugar in my diet, along with most red meat, and moving to a mostly vegetarian with some chicken/turkey/fish. And it's STILL taking forever to lose weight! I have had doctors say: post-menopause, medications increasing my appetite, not enough exercise (what??!!!), portion control on eating - you name it, at some point they've said it! Which really means, there's no single magic bullet, and it's going to take a long hard slog to finally lose the weight.
So, unfortunately, my best advice has to be hang in there, keep making small changes, and don't get discouraged. It's not going to be easy, but even little changes can add up to another pound gone, and then, eventually, another. Keep going, and know that while some people on this list can eat anything and not put on weight, there are many more of us in your boat with you. I am DETERMINED to finally lose this extra weight; I have faith that you will, too.