"and then just settled on leaves with meat or fish and cheese."
So you were ill as you were not following the diet properly, missing out the most important bit of the diet - vegetables - and just eating leaves instead.
Loads of vegetables (that are not leaves) are allowed, eg courgette, aubergine, tomatoes, peppers, brocoli, cauliflower, marrow, squash, onion, mushrooms, beansprouts, sprouts, cabbage, okra, leeks, celery, pak choy, green beans, fennel, aparagus, bamboo shoots, avocado etc.