If the findings of a recent study on obesity are to be believed then the movie portrayal of obese people as Lazy and less sharp indeed reflects the societal perception.
Above: In the recent movie,Shallow Hal, Gwyneth Paltrow plays a character who is morbidly obese.
A recent study has found that, people perceive that those who have excess weight are not that bright and are slow as well. In addtion, the society in general associates poor personal hygine with obesity as well.
Although in extreme cases of obesity, like in extreme cases of anorexia (a body weight too low than the ideal body weight); people can become less agile, less hygienic and slower on mental sharpness; for obvious reasons; but what the study talks about is just the perception. And a Perception, needs not to be true; Always.