I can honestly say that I have never been on a diet. It must be just something in my natural metabolism. For the last 40+ years my weight has not varied more than 10-12 ponds around a mean of about 155. When I stop working out so much my appetite drops and picks up again when I become more active.

I do think all these fad diets are nonsense though. As long as one eats a healthy variety of foods while avoiding large quantities of things known to be unhealthy (fats, salt, sugar) what does not matter, just how much in calories. Oh, and one can never drink too much water, while sweetened drinks are terrible.