People can be so bitchy. In order to avoid bad form, take care with your terms.
Just because people around you talk crudely of 'slim people', doesn't mean you have to stoop to their level. That doesn't make it okay.
In order to be a kind and nice person, call 'slim people', people with slim-PWS. They are people first, you remember that.
Calling folks 'slim people' degrades their humanity. The fact of their slimness isn't more important than their personhood. They are more than just slim. They are people with lives, jobs and a feisty attitude you wouldn't believe.
They are special, they are normal. Some of them are freaky, but we won't let on. Slim people are not what people say they are. They are good peopole, living with slim, and I really think they deserve some respect for that.
So please, if you see a with slim, be sure to help them out, whether they ask you for it or not.
And if you're a slim person reading this, never forget: You have slim, you are not slim.