I have loosely been reading through this thread reading point for and against each argument and this is my take on it.
My background:I have a Bachelors in Exercise Science from a reputable university while being able to play Division 1 baseball and professional as well.
So this is my take on diets in general and some of the way some numbers are skewed for various industries to sort of twist what they want it to say. Most beneficial things can come from a double blind study, that way neither the person participating or the person advising can achieve the "placebo" effect and have benefits just by what the other person says. Neither one of them knows so that way in a sense it is a "pure" study.
My overall take on a diet, too extreme to one side or the other is going to be bad. As mentioned before, just by the sheer genetic and physiological make up of the human body, we are omnivores. There are certain vitamins and minerals that the human body needs from meat, as well as your vegitables. If your body isn't getting red meat, it will lack a lot of important minerals such as iron. And if you're into competing (not just in sports, but running or exercising) your body needs to replenish its creatine systems. Yes, the almighty creatine you hear bodybuilders supplement with, originally derived from red meats and fish, than was isolated when they saw how beneficial it was for skeletal muscle.
However you simply cannot only eat meat, as you are well aware of. Any type of meat, whether red meat or fish, has fat in it. Without fat, muscle cannot hold itself together. However, too much will significantly increase your LDL cholesterol levels, and without exercise, this can put you at a much greater risk for heart disease. Cholesterol has a lot to do with genetics, studies have shown, but your diet also contributes in control what you can.
You need plenty of vegitables to help provide your body with some fiber and many other nutrients to help keep your system in track. Not only does this help your digestive system, but your immune system and many other physiological functions. Uncooked and unhampered vegetables are some of the most pure natural forms of vitamins and minerals. However you simply cannot eat all vegetables without getting some meat, your body will not get the nutrients it needs. Yes, you can supplement protein, or iron, or anything else. But the best source of anything, is in it's natural state. No supplement can equal the bioavialiablility that mother nature gives you. Same concept with VFT's and artificial lighting
A lot of vegans, and even some I know, have told me that after being vegan for a while, when they ate chicken or steak or whatever, they had diarrhea or other problems. This is because their body in a sense has rejected some of it because their digestive track isn't sure how to handle it because it hasn't had meat in a while. Your body needs a balance of both.
And in no way am I knocking one or the other because I am not. Too much meat will definitely cause health problems, however not having any can cause a lot of problems as well. There is such thing as too much of a good thing. I tell this to patients I work with in the hospital all the time. They ask me, "I don't understand why my blood pressure or cholesterol is so high, all I eat are nuts/spinich/etc." Then I ask them how much and their serving size and they show me. So I tell them the same thing.
Everyone needs meat, however the way the American diet is setup, that seems to be all anyone eats. If you take your plate, divide it in half. One half should be your vegitables. Take the other half, and divide it in half again. One of those should be your lean meat (chicken, fish, a lean steak) and the other should be your carbohydrate. I read someone said this before and they were right. A complex carb is what you want (brown rice, wheat bread, whole grains, etc). Simple sugars, although filling, are the reason why your hungry 30 min after you eat. It would be like throwing a stack of newspapers on a fire vs a nice oak piece of wood. The papers go up in flames and burn quick, same concept with simple and complex carbs.
Anyway, that was my 2 cents. And once again I want to reiterate that I am not knocking either or. Love this site and how helpful it is. Meat is good, however the way modern society views it with how much we eat it, is not good.