When I cycled 25 miles a day, Monday to Friday, I could eat /anything/ in huge quantities without a problem. It makes sense, but not when you add up the calories; I was putting in way more than the most optimistic calculators said I was spending.

Then I moved closer to work, and had a total of maybe 20 minutes on my bike every day - but this being a cheaper bike I could leave it locked up outside (with a decent lock, natch) so it was my primary form of transport for everything - going to the shops, commuting to work or meeting friends out and about in town. I was still eating whatever I wanted albeit in slightly smaller portions without putting on a pound.

Whilst it's interesting and valuable science to discover quite what on earth goes on when we eat things, if your biggest concern is not putting on weight, why not do exercise that makes you sweat for 20 or 30 minutes 5 days a week? Seems much easier to me - and satisfying because you don't have to deny yourself anything!