I've been lurking for a while, but this topic brought me out of the woodwork.
I'm in almost exactly the same boat as blubikegirl. Vastly overweight, doctor on my case, blah, blah, blah. Heck, 250 is my next interim weight loss goal.
What I have found to be effective is controlling the fat in my diet. I've been using FitDay (Google on it) on the recommendation of this list. It helps simply by making me aware of the "shape" of my diet. There are some foods I simply don't buy anymore 'cause I can't afford the fat.
As for biking - ride every day. 3 miles a day is close enough to 100 miles a month. My point is that getting out and riding is much better than staying home close to the oatmeal cookies.
I also make sure I ride to the drug store for any prescriptions, bank for quick deposits, that sort of thing. The miles add up, I get a workout and the scale thanks me.
Don't forget to have fun. We've been known to ride to a swimming pool, swim, ride to dinner, then ride home. It's our version of a triathelon
If you are careful of dinner, it works.
Good luck. (I need it too!)
Give big space to the festive dog that make sport in the roadway. Avoid entanglement with your wheel spoke.
(Sign in Japan)
1978 Raleigh Gran Prix
2003 EZ Sport AX