Stationary Bike Fat Burning

Dear Dr Darden
Do you burn more fat on a stationary bike at level 20 15 minutes or level 15 25 minutes?
Same speed.
Thank you.

What kind of stationary bike? Mine only goes to level 11.

Shwinn recumbant.
Goes to 30.

Hard to know what those resistance numbers mean, or if the scale is even linear. If you could get a watt reading from the bike, that might be a little more helpful. At least you could estimate the mechanical work being done. But calorie burn is dependent on the entire metabolic output of the body, which includes things other than the mechanical work transferred to the bike.

What kind of shape are you in? That can make a huge difference on the fat burn.