The only thing worse than a hypocrite lecturing about food choices is a fad diet know-it-all. Right now I have a friend lecturing me about the evils of gluten and she isn't even gluten intolerant. She got on the bandwagon for that about 2 months ago. Soon it will be something else.
I know a lot of people do the gluten free diets with good results but she makes up her own rules. She eats as many corn chips and tortilla chips as she wants and ignores the fact that they contain flour. She also eats as many potato chips as she wants and still manages to act like she is doing the "healthy" diet and has the right to be critical of what other people are doing. It would be sort of funny if it wasn't so obnoxiously hypocritical.