There's all sorts of quality research indicating value judgments based on externals, including weight, looks, body adornments, clothing, etc are actually the norm, not the exception. There's also research that indicates that lack of self-confidence is not necessarily correlated to body image - some of the most unhappy people I've worked with were "beautiful" or "perfect" in conventional ways, but absolute wrecks on the inside. Conversely, there are people who are rock solid psychologically who are overweight, scarred, missing limbs, or otherwise body challenged.
Johnathan's irritation with the generalization was warranted. That kind of "broad-spectrum armchair psychology" makes me mad, too.