Why do slim people dislike those who are fat? Researchers at the University of British Columbia discovered that it may actually be an immune system response:
From the taunting of the chubby child in the playground to cruel jibes at fat people in work and social settings, few could doubt there is widespread prejudice against the overweight. However, according to research reported in Evolution and Human Behavior some people suffer abuse because being too fat is mistaken by the brain for a sign of disease.
Researchers say the immune system can be triggered into action at the sight of obesity because it doesn't like the look of what it sees, and associates it with infection.
Just as it orchestrates attacks on viruses and bacteria and triggers nausea at the hint of bad food, so it sends out signals of disgust in some people at the sight of an obese body that is designed to encourage avoidance and survival.