I think the main point is 'regular' exercise, which is more than once a week. You have to live an active lifestyle if you want to keep your metabolism high. That means not using lifts or escalators, walking down the shops rather than driving, taking the dog out every day, that sort of thing. Hey, maybe riding more than once a week.
By doing all these things say, on a daily basis, you keep your body in fat burning mode. If you live a slow lifestyle all week and then do a bit of riding on the weekend you're probably not making much difference, in fact you're probably doing more harm than good by subjecting your body to kick ass effort after a week of eating monster munch.
A friends (young)husband died recently from a heart attack, I met him once, chubby chap. By all accounts though he was 'quite fit' because he played badminton once a week which had every one shaking their heads at the funeral. Once a week of strenuous effort after 6 days of doing nothing. That's not quite fit, it's a suicide pact. Load up on cholesterol all week, shock your body into doing something difficult for 60 minutes, repeat…..
No wonder it handed it's cards in. At least if he'd have just bloated out all the time there would have been no stress on the poor thing.