If you are both at 100w exactly and assuming you are both riding the same distance:
- She would finish first (lower body weight)
- You’re ride will take a bit longer, and you would burn more calories
In actuality, you are probably both riding the same distance and same speed. So your power can’t be identical. You would have to be putting out a bit more power, and correspondingly you would burn a bit more calories.
So you would burn more calories, but only because of body weight differences (not general fitness or FTP)