I really adore my dieting friends, but truly hate getting fitness, diet and nutrition advice from them--especially since they don't exercise (and if they do, it's always the three same lifts at the gym--over and over and over again), they park as absolutely close to the building as possible so they don't have to walk across the street to get to work (and I ride 10 miles in almost daily), and they jump on all of the fad diets (a few are hardcore Atkin's dieters who always bounce back to heavier weights once they give up on the diet--but never learn and go back on it again.)

ok, so maybe I'm just talking about a couple specific friends in particular...hrm.

Moral of the story: listen to their advice with a smile, but don't buy in, and don't argue. Arguing = stress and stress isn't healthy. You know what works for your own body.