Calories are burned by exerted effort. The total calories burned is determined by the duration of the effort. My husband burns more calories per hour because he weighs more, so just the number of calories it takes to fuel his body at rest is more than mine. It take more effort for the heavier ride to get from point A to point B (except on a descent), but then you have to factor in wind drag, rolling resistennce of tires, etc., etc., etc.
Blah-blah-blah.

So here, have fun. Don't ask me to explain any of it.

http://www.kreuzotter.de/english/espeed.htm

http://www.analyticcycling.com/