The 20-year-old was criticised by SkinnyGossip for her appearance in an ad for fast food company Carl's Jr, in which she can be seen eating a hamburger in the back of a limousine.
"I thought cannibalism was illegal?!? If that's not a very different species of cow, Kate could be in legal trouble!" the site wrote.
In addition, photos of Upton on the runway of several fashion shows were posted, with the author of the post claiming that the model was at least "30lbs too heavy" for the bra and underwear outfit she was wearing.
"Guess who?! Yes, it's the lovely Kate Upton, confidently lumbering up a runway like there's a buffet at the end of it," the article read.
"And I still ask: what the heck? Has fashion become this? Well - we know it hasn't, so let's not pretend this is fashion. She looks thick, vulgar, almost pornographic - and she is a solid 30lbs too heavy for this outfit."
The post continued: "Huge thighs, NO waist, big fat floppy boobs, terrible body definition - she looks like a squishy brick. Is this what American women are "striving" for now? The lazy, lardy look? Have we really gotten so fat in this country that Kate is the best we can aim for? Sorry, but: eww!"
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