I understand that most of the time you are required to take a fitness test and have your weight and what-not taken, I am overweight and want
to know what would happen if they find that you are over-weight, will they not take you in? will they require you to do anything about it? I've
been working on my weight and don't expect to immediately fix it but i just wanted to know if it was going to be a huge problem for them?
You are required to take a medical test, but I think calling it a "fitness test" is a tad misleading. They are testing for "narcotic drugs, communicable diseases, HIV, AIDS, physical and/or mental illnesses. After entering Korea, applicants must submit themselves to a medical check at a government approved hospital, public health clinic or general hospital."
This pretty much means you have to submit one test before getting your visa and another one when you are applying for your Alien Registration Card (ARC). The test is certainly trying to ascertain if one is fit to teach in a school, but it's not asking if one is "fit" or in shape. As long as your weight isn't hindering your ability to teach and walk around a classroom for a few hours a day, then there will be no problem. They will not require you to lose weight.
However, some schools (hagwons mostly) have been known to cut teachers loose for some silly reasons. As you might have read, hagwons don't operate like educational institutes, but rather as small companies that value the opinion of customers (or mothers in the case) above all else. This means that some teachers get canned for superficial reasons, i.e., "too dark", old age, visible tattoos, unkempt appearance, refusal to shave long facial hair and even having a prosthetic leg. Of course, those traits have little to do with teaching ability, but in the end, it's the boss who has the final word.
I did not list weight above because I have personally never heard of such a dismissal. On a simple stroll around the block it is not uncommon to run into a plus-size teacher of either sex. Some heavy-set teachers might have trouble finding clothes and perhaps a few extended glares might come their way, but it will not affect the status of your employment.
Of course, being in great shape is always the healthy option and it sounds like you're on your way!
If anybody has any questions, just send me an email at firstname.lastname@example.org or leave a comment