you can eat meat, fish, cheese, eggs, plus all manner of fats so butter, oil, mayo
you have to limit your veg intake though - maybe a few sprigs of watercress but not more.
And no fruit, no bread, no pasta, no potatoes, no proper amounts of veg, no milk, no nothing else.
It does work - definitely. But I really don't think it can be healthy. I believe in the low carb thing (am doing a sort of low GI diet right now which means reduced processed carbs - no white bread, pasta, potatoes, sugar - but you can have eg, veg, fruit, pulses).