I am a huge sweater too... and I am not overweight anymore, but still sweat ridiculously! I sweat more quickly and more profusely than a lot of other people around me, my father also does, while my sister and mom for instance don't.
There are some things that trigger it more as well, like of course I sweat doing exercise (and often way more than others) but it is more of a problem when i go from a cold environment into a warm one.
I used to mind it a lot, and it is still a bit of a problem in wintertime when it gets cold and I start sweating as soon as I enter a bus/underground train/shop and therefore in my jumper and coat get quite smelly quite quickly. I had to carry a deodorant with me all the time in London winters.
I also have ice cold skin while I sweat (so I know the sweat is doing it's job very well), I guess my body just reacts like that. Today in dance I would at times sweat onto the floor when I had to stretch and bend over (which is gross) and there was at least 1 other person who had this problem as I saw wet spots in someone else's spot too. Usually it is not a very bg problem anymore though, I have just acceped that I am the way I am and it is not pathological yet I'd say, just more than average.
I also, by the way, get a very hot head and very cold limbs in the evenings when I am out with friends and therefore excitedly talking (it happens more in winter than in summer, and not at all if I am just with my boyfriend, or my family). I go red like a tomato and feel feverish, but have no fever. I guess my body is just nto that good at temperature regulating! Oh well, there are worse things!
Camy