The advice I once received from a skinny fellow in his 60s or 70s was, the best diet is pushing away from the table before you're full.
My recipes use no substitutes for sodium, fat, or cholesterol. I enjoy margarine and hate butter. When I make Fried chicken, I use a whole dozen eggs, yolks and all, to soak the chicken in before rolling the pieces in a blend of flour and spices. I cook them in Crisco shortening and use lots of paper towels when they come out to wick off the grease.
Pizza, spaghetti, manicotti, lasagna, ravioli, and a few other Italian-American dishes are sacred. Mess with them and you might have a visit from a couple of Italian guys from New Jersey.
Eggs are bad for you. Oh, wait, no they're not. Oh, wait, yes they are. No, wait, no they're not. I used to be indecisive, but now I'm not so sure.
I have noticed that the ladies have a natural affinity for things that help them stay thin. They will eat, for instance, Vrai's tuna recipe. Open a can of Bumble Bee or Starkist Tuna (Albacore or not) packed in anything, and I will leave the area. Warm it up, and I will leave the house. Force me to eat it, and I will make sure that when it comes back up, it will end up on the perpetrator (aka cook).
I like some things that are diet-smart. Popcorn. Hard-boiled Eggs. Corn tortillas (but by the time I've fixed 'em up with margarine and salt I guess they're fattening). Salads.
But don't turn it into a whole new way of life. I will exit stage left.