If you haven't tried this fast-growing cycling sport, you should.
You can burn up to 1,500 calories an hour—or nearly 25 calories per minute.
It entails pedaling heavy, hard-to-turn monster bikes and tackling all types of terrain, all year round, says Mike Curiak, record holder for the 1,000-mile Iditasport Impossible, a fat tire biking race.
Reality check: that kind of calorie burn depends on your fitness and strength levels, and your skill.
But regardless, it's sure to be one hell of workout.