dumb questions that we should have asked a long time ago: how far is your commute, how long is it taking you, and what kind of bike are you on?

if you're doing a 20 mile commute in 1 hour on a single speed cruiser, your weight loss makes sense because that would require a LOT of energy.
if you're doing a 5 mile commute in 1 hour on a triathlon bike, your weight loss numbers would be scary.