Well,ive been 3 months in the brazilian amazon, with an indigenous tribe. i will share a little of their aproach to the diets.
there are many diets with difrent purposes, but all have common things that you should avoid, meat, fatty food, salt, sugar, and sex.
and the only form of tobaco they use is the rapé, wich you can use in any diet except the kambo diet.
you cant even eat sweet fruits. and they say that about the sex question, they even avoid contact with women, they say they will absorb some of your spiritual power, so its not just about the sex for them.
if someone is sick, they make a closed ceremony, where just some people drink the ayahuasca and stay silent around the paje that will chant the "meka"to a pot with caisuma (fermented korn drink) for like 6 hours. the sick person will drink the caisuma and make a diet of 15 days.
there are also the diets intended for study. it can be also with the caisuma, or the one i've done, the janipapo diet. janipapo is a fruit that produces a black pigment. the paje sings to the pot, then they paint your body with the janipapo, and then you drink the rest. then you stay to months with that basic diet also, drinking ayahuasca every 2, 3 days, isolated from the village. ive eaten a lot of rice, cus-cus, pasta and some very small fish.
then there are some more serious diets.
they have a tree that has a tuberculos kind of root (like a potatoe), wich im not allowed to share its name.
they will make an oath, then they will eat the root, while praying to that sacred and powerfull spirit saying what they wish to acomplish with that diet.
then they enter a 1 year long diet, where they barely dont eat and dont drink water for the first 4 months, just having a litle bit of caisuma, and drinking a lot of ayahuasca and using a lot of rapé, completely isolated. in the next 2 months they are allowed eat just a little bit of coocked korn, rice, and little fish. after that 6 months they could choose to go back to the village, and continue a simple diet for the rest of the year, being allowed to drink water again, of they can continue the previous 2 monts diet for the rest of the year, going deeper in their studies.
the really serious one (only 2 people in the village attempted to do this one, and one of them died) is the diet of the urunu (boa constrictor). they will eat the boa's heart, and drink its saliva. then they begin a diet of 2 years, wich they can only eat small animals, basicly the same diet of the serpent. they can drink caisuma, water, and take ayahuasca and rape. if they break the diet before the 2 years are finished, the spirit of the urunu will come in their dreams and kill them.
there is also the kambo diet (phylomedusa bicolor) for cleansing purposes, where you follow the basic diet, and cant also smoke or take rapé.
now, something more personal:
i usually follow the basic diet (personalised of course) before drinking the medicine, but being in the city of the santo daime, with so many churches, it happens that ocasionally there is some interesting work that you hear of the day before it happens. so i've been in some sessions without doing any previous diet. in my case, being vegetarian and eating fatty foods only very ocasionally, i was breaking the diet only beacause the sex and the sweets. i feel the experience is not so profound, and very ocasionally i purge. but it is nothing so relevant really.
and as someone stated above, if you dont ejaculate, or dont reach that near orgasm state, it wont make such a difrence. but that it in the santo daime type of ayahuasca. as someone else said, if it is that kind of brew with a lot of caapi, i prefer to make at least one week of diet.
i also tried to fast before a ceremony.... the result was: i was worn out before the session, and all i could think about was food
Healing someone is an act of love, but how can you love someone whitout loving yourself first?