On a city bike a completely inexperienced cyclist can easily do 20 for hours. That means that in 2 days it spent less than 9 hours actually biking. At a leisurely pace. I'm in no way a skilled cyclist but on my sports bike I can do that in 6 hours. And yes, landscape matters a lot. 180 km of alpine roads is hard to do in 6 hours. 180 km of normal roads is well doable. Biking 3 hours a day for 2 days is not losing weight. Especially since you need to eat a lot to do that