Victorian perceptions of fat children as slothful and stupid have influenced the way obese pupils are viewed today.
This has led to efforts by schools to improve children's diets and decrease their weight - from government healthy-eating initiatives to Jamie Oliver's high-profile war against fast foods.
Sander L Gilman, professor of psychiatry at Emory University in Atlanta, Georgia, has studied historic and contemporary attitudes to excess fat. In Fat: A Cultural History of Obesity, he argues that fatness is now seen as a question of public morality. "The moral panic about obesity seems to have filled a gap left by the restructuring of the moral panic about Aids," he said.
But he says this link between obesity and moral depravity is not new. For example, he quotes William Wadd, surgeon to the Prince Regent, who announced: "If the Goddess of Wisdom were to grow fat, even she would become stupid." Similarly, Fredrick Douglass, the 19th-century abolitionist and campaigner for women's rights, argued that skin colour did not affect intelligence. But, he said, "gross obesity" tended "to induce mental stupidity ... coarseness of feeling."
And in his novel The Pickwick Papers, Charles Dickens created Joe, the overweight servant boy defined by his huge appetite, blank expression and his ability to avoid work by falling asleep. It is, Professor Gilman points out, a description of "almost medieval sinful sloth and stupidity".
Fat children also served as the public symptom of a middle-class ill: overindulgence. The reasonable, hardworking man is contrasted with the overfed, overpampered boy. "The reward for the thin man is life," said Professor Gilman. "The fat man dies young and unhappy."
This culture of condescension survives. Last year, a survey of 80 7- to 10-year-old showed they almost all made a connection between being slim and being happy, popular and academically successful. The overweight were seen as miserable, unsuccessful and likely to be bullied.
But in recent years, obesity has also been equated with illness. The term "epidemic", usually applied to contagious diseases, is now used to refer to obesity.
This, too, has its origins in history. One of the first uses of the term "obesity" appears in a 1620 health handbook. Its author notes that "a fat and grosse habit of body is worse than a leane, for besides that it is more subject to sicknes."
This perception of obesity persisted through the centuries. Dickens' fat boy was seen as suffering from a chronic illness. "Obesity for the Victorian is an illness unto the death," Professor Gilman said.
And these perceptions prevail. In 2004, the Government warned today's children would be "the first generation to die before their parents as a consequence of obesity". It also predicted obesity would lead to more children developing diabetes, which would, in turn, lead to blindness and amputations.
In 2007, researchers in Massachusetts said having obese social contacts could increase a person's tolerance for their own weight. The New York Times reported that obesity could "spread from person to person, much like a virus".
"It was all cobblers, scare tactics on a lunatic scale," Professor Gilman said. "Yet, in spite of these regular revelations of hyperbole and poor science, we remain in the middle of an obesity epidemic."
So talk of an epidemic, along with healthy eating initiatives and replacing breaktime biscuits with fruit and yoghurt, are the legacy of centuries of anti-fat prejudice.
"Childhood obesity comes to hold a special role in defining the dangers, to society as a whole, that the perception of increased bodily weight implies," Professor Gilman said. "Fat children signify a base change in society for the worse."
'Fat: A Cultural History of Obesity' by Sander L Gilman is published by Polity
DIFFERENT FOCUS ON BEATING THE BULLIES
Pupils who bully classmates because they are overweight or different in any other way are the focus of this year's Anti-Bullying Week.
The annual event, which provides schools with resources to tackle bullies, will focus on the fact that prejudice and difference are often used as reasons to single out victims. For example, pupils may be picked on because they are brighter than others or from a different background. And increasingly - with the public demonisation of obesity - children are bullied for being overweight.
This year's Anti-Bullying Week runs from November 17 to 21. It is accompanied by a resource pack for teachers and includes a DVD, posters, lesson plans and a tip sheet for teachers. It also includes cards and games to help pupils express their emotions and a list of external agencies that can provide additional support and advice.