I specifically singled out fad diets, weight-loss diets, and calorie-restriction diets.

I do NOT think that making dietary changes is a bad idea. I try to improve my diet in terms of getting enough fiber and water, getting my servings of fruit and veggies, etc. I like seeing the newest food science about what the best mix of fat/carbs/protein is, what foods are good for your heart, etc. I just think you need to take it all with a grain of salt and not beat yourself up if you don't live up to your high-minded ideals.

Feeling guilty just makes you want to eat more crappy stuff, anyway!