I am not a scientist, doctor or even a health expert. I have read 50 books or so (see Eating Well) about this general topic. I have a skeptical disposition about any final health solution to the human condition and life on earth. I follow many health bloggers and have been to dozens of health conventions in Toronto where I live with my happy little family of four. I followed a vegetarian diet for some years and became unwell, but in fairness and full disclosure, I was not exercising daily back then as I am now and I was also occassionally smoking. I put on 50 pounds which I have since shed. I use the concept "Skinny" as a metaphor within one's genetic inheritance; i.e., if your parents were rotound, then be skinny-rotound, or as healthy as you can be within the margins of your genetic makeup; I don't use the concept in its literal sense and I hope you won't either. Some folks have a genetic lean to being overweight as low as 25 percent and as high as 80; however, having said that, I know  many people who were skinny teenagers who are totting around an extra 100 pounds in their fifties and a few even much more than that.