does bike riding help? will i lose much weight?

[Plugger D]

if i bike ride for 2 hrs a day, and eat healthy, will i lose weight fast?
and how much weight would i lose if i do this for about 2 weeks? (i also will swap around activities that ill do, like walking, joging )
(im 13, 45kilos, girl )
and will this make me lose my baby fat?
:S and does bike riding make you lose weight only from your legs? or from everywhere?

thanks