help me correct,please

Rently, most of the Hong Kong people become obesity. A group of people think that slimming centres can help them to reduce weight and keep their body shape. However, I do not this is the only way for them to oppose overweight.
First of all, I think the fee od the slimming courses, that are provided by slimming centres, are very expensive, some of them even need more than five thousands. I do not know the reason of some people to use nearly half of ther salaies to pay the slimming course, what are materials that slimming centres use , and are those materials are valuable, these question always in my mind because I think that there is another way for them to choose. At the same time, they can reduce their weight and save their money.
I suggest that they can try to set up a dietary meau with low fat and low oil, but one thing is very important, people must need minium energy requirement for a day. Moreover, they can try to do exercise everyday to speed up the efficiency. I recommond to choose swimming,because swimming can join with friends, they will not think that doing exercises are very boring.
Moreover, slimming centres may ask them to join other plans as those plans may have discount, but they need to pay more money, so they must check the contract carefully before they sign.

2007-07-19 23:48:00 補充：
i may not change yrs comp very well , but u can just looki can change the last part , i really daon't what u think .