I was a so-called vegetarian for over 18 years. But, I ate fish and sometimes chicken. It was okay, since they were only small animals. A couple of months ago I met a new friend that said while being vegetarian was good, becoming vegan was even better. So I watched a few videos on veganism and learned how terribly animals are really treated on farms. This was near the end of last year. I'm never eating or using an animal or animal product again.

Diet For a Small Planet made us vegetarian (although not religously so) for environmental reasons. After reading McDougall, China Study I went pretty well vegan (ok I've always hated cheese and eggs) - for health reasons.
My wife has concerns over omega 3/6/9 so there is a bit of fish every few months and eggs weekly for the kids. They've also cut back on their cheese addiction (I think?). But my wife counters that a vegan, and even a vegetarian diet is highly unusual - more so than an Atkins diet. Atkins diets have existed for long periods of time. So it's impossible to justify a vegan diet, to my wife, for our kids.

In the end we all die of something - how much are you willing to do to extend life a bit? In our case weight and cholesterol levels are excellent - even on a omnivore diet.
In the past 5 years we tried a 100 mile diet and have shifted to more local and organic foods and now consider ourselves to be "whole food vegetarians".
Parents have moved to a mostly vegetarian diet and their weight has come down. In our case we did loose some weight going veg - and the winters can be very cold now - even with an undershirt, long sleeved shirt and a sweater or two when the house is around 20C. The cold winter drove my wife to get a free range chicken and cook it up. Another friend was veg but also has been trying to gain weight by eating chicken - without success.
It doesn't help that the kids are well below the 5th percentile for weight and height (but look better by the WHO numbers, and their parents are slightly below average in height). There are comments from friends that our kids need to gain more weight and grow taller.
In a community where a veg. diet (my Indian friends) is the norm these questions don't arise! But our non-religous homeschooling, local whole food diet, voluntary simplicity and vegetarianism are very counter to people around us.
My belief is that those who stretch themseles tight will snap and go the other way - it does not pay to be extreme. Also as we power down and go into peak oil - our diet will have to be omnivoe - a vegetarian diet is not possible, or sustainable, in our climate without massive amounts of energy input. A veg. diet is a luxury of unparalleled prosperity.

It started four years ago when my doctor told me I needed to start taking a cholesterol lowering drug, I was 46. I have had high cholesterol since my 20's and thought because I was at a healthy weight and athletic that my cholesterol numbers didn't matter that much. Wrong!
I knew about Dr. Ornish's work reversing heart disease with a low fat vegetarian diet so I gave up all meat except for fish for the first year and my numbers dropped enough that my doctor commented on them. I then became a vegetarian for two years and my number dropped a little bit more. Finally a year and half ago I became vegan and that is when I had a BIG drop and my doctor's jaw dropped and could not believe that diet alone caused such results. I should mention that I focus on a vegan diet that is a whole foods diet,
I don't eat allot of processed foods.
Along the way I did a fair amount of research on where our meat, dairy and eggs came from it broke my heart. I could not in good conscious be apart of it by paying money and consuming animal products. I understand that there are so called "humanely raised" meat available but I decided that even though it had that label (what does that really mean anyway??) I didn't need to have something killed or kept in confinement in order to be nourished. I feel great about my decision.