It's a five hundred calorie per day HcG diet so it's pretty similar to fasting (near vegetarian), but I still have to eat a certain amount of meat. Then in 40 days, I spend two days eating anything at all every half hour to load back up on brown fat. Then the cycle begins anew.
So, I've got no idea how a priest would react, but this is doctor supervised.
(The idea is that the HcG makes the thyroid think you're pregnant so it locks down your brown (essential) fat reserves, which is normally what the body burns first. It also prevents your body from burning muscle, so it burns your white fat directly.)
I can tell I've lost a couple of pounds already.