Originally Posted by
The_woo
...
Just in general the machine runs more efficiently when it's lean.
The more efficient metabolism gets fat with the fewest calories. The fattest for the same intake and output are the most efficient. Ask Indurain.
For this thread, I'd wager all things being equal (and they are not) that the fatter person puts out more watts longer. I think we'd agree the typical fatter person is less trained, so that would skew thing. Many (for <1 hour) fatter have higher power and over single digit body fat composition cyclists.