Cycling has been a success story for me as well, but only as long as it lasts.
in 1996 I became a catholic vegetarian, or as some say, a pescarian. At the same time I took up cycling in the weekends in addition to commuting. Then, I happened to get a 5-mo. stint for which I had to cycle a total 40K/day to/from 2 railway stations, broken up in 4 fractions.
Unfortunately, I was not able to find a job that offered a similar commute later on, though the typical 2x10K commute to the railway station remained (the other station was mostly close to the job). However, in 1997 I stepped up the distance by cycling more in the weekends and finally cycle-touring for 4,5 mo. in NZ and Oz and lost even more weight and also had to give up my pescarian lifestyle for lack of proteins.
Since then I haven't cycled as much and probably for wasted muscles gained weight rapidly.
My main problem has been the too large difference between weekly distances in summer vs. winter, when everything is dark and gray and there are no organized bike rides being done..
summer distance are hence extreme caused by the randonneuring I started to do in 1996 and kept doing until 1999 when I participated in Paris-Brest-Paris.
However, when I DNFed for that one in 1999, I rapidly gained weight to my pre-cycling weight and up till now have not been successful to keep it off, despite a full year of cycle-touring in 2000-2001 and some other largish bike tours since then..
Why? The tours are for a specific period, after which the weight piles back on in frightening speed.
The only solution is year-round cycling.. and for lack of a suitable commute, it's got to be the spinning classes.. but even these take a winter break around X-mas (put on 5 kg in just 2 wks)..
Sigh! Now I'm going to try the Cyclic Ketogenic Diet as I'm still 12 kg overweight, despite 3 mo. of cycle touring (only net loss of 5 kg).
Fietser