How is it acceptable to have a go at someone due to them being 'thin'?

what i have yet to understand is why, whenever someone says something horrible about another person, they are automatically jealous?

Can't whatever they've said just be their opinion?

The average person knows that saying something horrible to someone to their face will hurt them.

If you're not doing it out of jealousy/spite, then you're some sort of sadist who gets pleasure out of seeing people upset and lowering their self esteem.

Size 4-6 at 5'9" must look bloody repulsive. Frankly below a 10 at any height is ugly. It's seen as you pandering into the popular cultural ideal; there has been a reaction against it lately amongst women, and men have always liked women with curves rather than protruding ribs.

nah i completely disagree, for example if i call someone 'orange gob' because they wear too much makeup it does not mean i am jealous of them wearing far too much makeup nor do i aspire to be them

there are more tactful ways of saying you're fat or you're thin.
for example you might want to tell someone who you think is too thin to 'eat some more' or maybe you could tell a 'fat' person to share their food? i dunno.
the only time i've been in this situation is when my friend goes on about dieting then i'll see her eating a chocolate bar, i then say "i thought you was on a diet" that usually makes her feel bad enough to give the rest of it away!

nah i completely disagree, for example if i call someone 'orange gob' because they wear too much makeup it does not mean i am jealous of them wearing far too much makeup nor do i aspire to be them

I do no exercise and overeat so they'd just laugh at my hypocrisy. I'm size 10 though. I think it's less healthy to be a bit thin than a bit fat. You can be about a size 16 and in healthy BMI range. Size 6s are usually below the recommended BMI.

That would mean you enjoy upsetting people. Why not tell them tactfully you think they wear too much make up and would look nicer with less? Rather than calling them 'orange gob'

well i can't say whether i enjoy upsetting people because fortunately i dont go round saying things like that...

but on the same rule what if someone calls someone fat? does that mean they're jealous?

Like I said, in my opinion people say horrible things to other people for two reasons:
1. Jealousy/envy
2. A enjoyment out of upsetting other people and lowering their self esteem.

I would say going around calling people fat falls into category 2. Going around making deragotory comments about thin people could fall into 1 or 2 because we know that a large portion of society does indeed strive to be slim.

No but you're doing it to make them feel bad. Why else would you say it? As a statement? Because if its just a statement then what is the point in it?

Size 4-6 at 5'9" must look bloody repulsive. Frankly below a 10 at any height is ugly. It's seen as you pandering into the popular cultural ideal; there has been a reaction against it lately amongst women, and men have always liked women with curves rather than protruding ribs.

so whats all the kerfuffle about then??? someone saying your slim/thin is surely complementing you given the fact that you think that most of society want to be like you!!!

I don't think BMI is the be all and end all of it though. There are much more associated health consequences of being fat (like high cholestrol, breathing problems, etc) than there are of being skinny I would say.

Stopping periods, losing hair and having potassium deficiency in the heart are worse, I'd wager.