Originally posted by: Red Dawn
I need to lose a lot of weight and also work on my coordination
You sound like a perfect person for instructors and other students to take out their aggressions on.
I'm not sure where you get your impression about marshal arts schools, but at my school the people who had more natural talent or were better helped out those who needed extra help, often after class for no money, even the instructors did that. And the vast majority of the people there took into account the skill and strength of their opponent when sparring.
That being said, for your purposes I would stay away from the more hardcore schools. I would go to one that is more oriented towards families or people who don't want to become the next Bruce Lee. Go visit them, watch a class, get a feel of the atmosphere. Two things to watch out for. Schools that emphasize competition (competition skills are different and less useful in real life than "normal" karate, so unless that's what you're looking for...), and schools that encourage arrogance and attitude about marshal arts. I don't want to generalize, but I've been to a lot of competitions and the biggest pricks are usually from a hardcore school where they are told that they are badasses. This is probably not what you are looking for for two reasons. First of all, since you need to work on general physical fitness before you can get good, I doubt the more hardcore schools will have the supportive atmosphere you are looking for. Secondly, those kinds of schools miss the entire point of marshal arts in a big way, and I can't recommend arrogance and marshal arts as a good mix.
To be fair to some hardcore schools, I've met people from schools where you train 6 hours a day and such, and some of them of really good schools. Arrogance and hardcore doesn't have to go hand and hand, but it seems to more often than at other schools. That's why I would go take a look.