Ahh, when I went from trainers and bare feet (summer wear) to the DM's. I suffered from sore heels where my skin wasn't used to the hard leather, so then walked around for ages awkwardly - that may have contributed?Overweight is subjective. I work with guys whose BMI would have the medical profession screaming 'morbidly obese' but they are fit, healthy, solid collections of muscles... all in the right place and functioning perfectly!
However, many 'thin' people suffer with PF; it is not your size or exercise regime that counts but your mechanics. Genuine DMs are not the issue but the way you walk whilst wearing them!