My brother recently started on something called the paleo diet. The basic gist is that paleolithic man evolved to eat certain types of food, and our bodies can't process our modern diets.
It basically limits you to fresh meat, fruit, and veg. Anything derived from grains is out, as are pulses, rice, dairy, salt and sugar.
It also works as a way to get rid of the highly processed, low nutrition, by-product and chemical laden rubbish that forms most of our modern diet.
He says it has made him feel amazing. Better sleep, more energy, more alert, and he is going to carry it on for the rest of his life. The weight has also just fallen off him but that's not his reason for doing it. He says he is less hungry and requires less food as his diet is so much more nutritional. He also eats some amazing looking meals !
It's not for me ..I already eat quite healthy without going to this extreme, but this may be interesting to someone.