There were two reasons: First, many people have an allergic sensitivity to yeast that causes reactions like hypoglycemia. Second, almost every prepared food has yeast in it, so it may have been a backwards way of getting away from pre-packaged foods. There are some really great yeast free breads that became kind of a meat substitute for me.
But, hey, I didn't eat cauliflower, brussels sprouts or mushrooms either.
This was supervised by a nutritional herbologist -- I didn't think it up on my own. (Although he wasn't the person who stopped me from wearing leather. That was a real trick, since at the time I rode a motorcycle as my sole means of transportation).
There are plenty of people who believe that the big problem with red meat is that the adrenaline that courses through the flesh of the animal at slaughter causes aggression in the person eating the meat. If it was just a matter of ethical slaughter, there are lots of options. Kosher meat is usually killed ethically, lambs don't struggle (I hear), and I just saw in my local organic market a sign about the chicken that they sell being raised with "respect" (no comments on the technique used to kill the chickens).
Peace.
~ ~ ~ All meetings end in separation All acquisition ends in dispersion All life ends in death - The Buddha