I have lost about 40 pounds and I've always biked. When I was younger I did road riding and then started mountain biking when I moved to Colorado for college. So I didn't take up biking to lose weight. I gained my weight after I hurt my back mtn biking on a rigid frame. After that, I couldn't even road ride short distances let alone mtn bike. I was barely able to walk for a few months. Like missliz, I got depressed and just kept eating as I had when I had been active all the time. Not a good thing! While my back was still healing, I went out and laid down a big chunk of change on a full-suspension bike so that the moment I felt better, I would be able to ride. After many months, my back did get better so I got to ride again but the first season I didn't really lose any weight and really didn't realize how much I needed to lose. Then, as happens so often, I saw *the* picture! The picture that made me realize how much bigger I was. So I changed my eating habits to the Atkins program, added more regular running and lifting to my routine, and continued to bike. So, to answer your question, I didn't add biking to lose weight but just changed my diet and now when I bike I realize how much easier it is getting up those mountains without the extra weight.