I didnt' say i associated vegeterian lifestyle with being skinny. I said it would be hard to put on LEAN MASS (a.k.a. MUSCLE) on a vegetarian diet. Putting on MASS in general on a vegetarian diet is not as hard. In fact, as someone else pointed out, almost every vegeterian I've ever met is not only kinda gross-looking, but also flabbier (even if they are thin), and the thing about the skin is pretty accurate. There is SOMETHING amiss about their skin tone. Not every veg, but most that I've met or know.
I'm no nutritionist, and this is by no means an "expert" comment. Just speaking from what I"ve seen/read/heard...
There is a girl at my gym who is all about vegeterianism and organic foods and raw foods and macrobiotics and all that. Despite all her "healthy eating" (by her standards) her ass is still the size of a small third world country.