While previous study had focused on the negative evaluations of obese people, often blamed for being lazy and not exercising self-control, the new findings published in the International Journal of Obesity suggests an explanation about negative emotional reaction towards obesity that can help understand why those attitudes toward obese people are resistant to change.

UNSW psychologist, Dr Lenny Vartanian suggests that moral judgement is not based on logic by an emotional reaction to obesity itself.

Although the scientific community acknowledges biological, behavioural and social contributors to body weight, a common belief in society at large is that one's body weight is almost infinitely malleable, said Dr Vartanian.

The problem with this idea of willpower is that we chalk it up to a moral weakness.

The recent research involved three studies, with the first being a survey completed by 300 American university students, asking how favourably the rated various social groups and how much they believed being part of that group was under an individual's personal control.

They were asked to rate obese people along with another 15 groups including African Americans, smokers, lottery winners, welfare recipients, drug addicts, homosexuals, the mentally ill, the elderly, homeless, rich and religious.

At the end, they were asked to rate the feelings of disgust they held towards each group.

The results showed the groups that were rated most negatively and with the highest level of disgusts were those perceived as having an element of personal control over being a member of the group.

Obese people were among the most negatively rated, on the same level as homeless people and politicians. Drug addicts and smokers were the only other groups rated more negatively and more disgusting.

A second study involving 125 different participants from the same university, with the only exception in using the term fat people instead of obese people revealed similar results.

A third study which involved 99 students from an Australian university with slightly different questionnaires, also revealed similar results as the two studies.

The findings provide strong evidence for disgust as a predictor of negative attitudes toward obese people.

According to Dr Vartanian, disgust is a basic emotion that promotes distancing from a perceived physical or moral contaminant. Such responses, he says, can be altered as a result of social influences. He refers to the attitudes toward smoking, which have moved from acceptance to disgust since the 1950s.

Attractive standards have shifted over time, with more curvaceous figures being preferred in the beginning of the 20th century and again in the 1950s, but more slender ideals being prominent in the 1920s and continually since the 1980s.

In parallel with this latter trend, attitudes toward obese individuals are worse today than they were 40 years ago.

It is possible that these body-type preferences over time have also become moral values, and that those who violate this moral value elicit a disgust response.

Efforts to change negative attitudes toward obese individuals, therefore, might work toward reversing this moralization process and reducing the moral value placed on leaner body types, said Dr Vartanian.