Just a short bookmark to note that since I upped my mileage
to 100miles/week, and two-a-day rides, my weightloss has
increased dramatically.
Initially I only had lost about 15lbs over 6 months at a
more modest 50miles/wk.
In the first 5 higher mileage weeks, I've lost 15lbs, the
second 2 weeks 10lbs more.
These last two weeks, I've ridden faster (from 11.7 mph,
average to 13.5 mph, average), and farther (from 10
miles/ride to 20 miles/ride average).
So, IMO, biking alone can help you lose weight if you are
doing enough mileage, and at a fast enough speed. Of course
you have to find your own 'threshold' for these.
Some people may find that threshold with less mileage, and
greater speed - gotta experiment.
In addition, I'm adding muscle to my legs, calves and yes, a
little to the upper body, although some of the apparent
'muscle' is just better defo, due to the loss of fat.
Thus 25-30lbs in 8 weeks has not resulted in any bad side-
effects for me, nor have I lost any significant muscle.
Energy and drive have increased markedly, as well.
Moral: When in doubt, bike a lot! ;-p
-B