You’ve said dieting does not work for you, and that you exercise. But, really… this doesn’t sound like much of an exercise program.
Now, I’m male, taller, and only now 42, but when I was turning 30 I weighed 230lbs. Not obese, but definitely overweight. Dunno if diets might’ve worked for me; I was simply uninterested in them. However, I committed to an exercise program that included cardio and swimming for 1-2 hours, 4-5 days a week.
I lost 50 lbs in about six months. It was hard and probably required as much (or more) willpower as dieting. But after that time I cut back to maintenance levels of 3-4 times/week… and I’ve kept the weight off for 12 years.
The only real diet change I did was to cut back from a soda a day to only a couple a week; I still went to lunch at McDonalds, for example, fairly regularly. Since then, as I’ve gotten older, I’ve gradually adjusted my diet even more – no more fast food lunches – but for other reasons (my chloresterol was also 230; now it’s 140).
Anyway, I live without all the restrictions someone who’s had bypass surgery must live with for the rest of their lives. All I have to do is make exercise part of my weekly routine – and a bypass patient probably has to do that, too.
Before having yourself cut open, I think it might be wise to try a more intense exercise program than just biking and walking everywhere. Something where your heart rate is elevated for an extended period of time – cardio, aerobics, running, swimming, etc.
If you combine it with a sensible diet, all the better.