they just don't look good

Because you were socialized to have that view. We are all just like robots being programmed by our environment.

On the other hand there are some basic things that are not based on your upbringing. An hour-glass figure is attractive (good for having children apparently) and a simetrical face is generally attractive because simetry means good genes in some way. But these basic things can be overridden by society so that you suddenly like hungry models or really fat women. Both very bad things from a health perspective. 

I agree with the OP's claim that we are mostly socialised into viewing fat people as ugly. I think it reflects the overabundance of food and the prominence of obesity in contemporary society.

Depictions of plump nude women characteristic of the premodern era, underline how bodily norms are dependent on the nature of our social context. In those times, a weighty figure was considered desirable amongst the upper classes, despite the fact that poverty was relatively prevalent. In contrast to today, obesity was rare and was an indication of wealth and high social status.

This contradicts the view that we are somehow biologically predisposed to be attracted to athletic bodies. Whilst I wont completely discount that there is some truth to it, IMO, our biological predispositions are overwhelmed by the values, beliefs and norms we pick up from everyday experience and our social surroundings. Human beings are learning creatures - this is what distinguishes us from animals. Our unique capacity for learning and adaptation makes it possible for us to overcome our genetic limitations.

Fat people are fat.

I'd never date a fat girl.

Cause they're ugly

[shallow but true]

Am I the only guy here that actually gets attracted to chubby girls?
There's a strange struggle there, I like the look of a thin (not skinny really) girl but when it comes to actually being with one, I do prefer a bit of fat under the skin. I guess it's my natural drive competing with my social imprinting. Really fat girls turn me off though. Middle is the way to go! (Words a swede lives by).

And the argument that 'fat girls eat and I don't want to pay for that' is quite absurd, I think. It's demeaning for women in general, completely irrelevant (dating costs, no matter the food expenditures) and this is the twenty-first century. Women can pay for themselfs, they do not need to be dependent on men anymore.

well therez two sides in the spectrum...most people want girls who are not too overweight or too skinny....both are very unhealthy...nowadays i think society looks at girls with "curves" at least a decent amount of meat as sexy....girls that are too skinny or too fat just dont cut out...

We as humans tend to go for the healthiest looking girl.

Too fat is unhealthy and it is instinct to back away because we don't want an unhealthy person to bear our children etc...

The same goes for stick thin girls, they are just as unhealthy and unatractive.

About a size 10 (UK) is a good size

Oh, so that's why a lot of the models are "underweight"? 

Actually you're right. Unfortunately I'm 23 and all I deal with is boys.

And honestly guys, someone who is slightly overweight does not look that terrible and its not like oh noes its the end of the world they arent PERFECT(I'm sure you guys are far from perfect yourselves). Because obviously, our purpose on this planet is to devote our lives to looking pretty for you and if we DON'T dedicate our lives to that, we are failures as women and should be shunned right? State your opinions but stop wording things in a way that is so disrespectful to women.

Also, as for my anti-man rants... I was raised to have self-respect. Male behavior doesn't sit well with me because most girls are actually still raised to just be gossipy and pretty so you guys still don't treat them with respect. The thing is, I actually do know that all of you being pigs here are all talk and trying to seem tough and cool etc. I know most of the guys in real life talk big all the time and talk so disrespectfully of girls they actually care for. I want you guys to actually stop and think about the fact that you are doing this. 

Also, I have a little grudge against "men" due to things like sexual assault. Some guys go a little too far to get laid. It doesn't leave a good impression of men in general when guys are willing to go to jail and traumatize a girl just to get their dicks wet.