I live in Southern California and there are tons of Vegans here. I have never met one that looked in shape. Most of them look like if I punched them their bodies would crumble, not that I would...well I might. Veganism is more like a religion, with a bunch of nuts trying to convert people. It all has to do with genetics, I know people who have smoked 2 packs a day, and been drunk most days of their lives and they live to 95. They never had cancer, or any other life threatening disease. Some people are ultra healthy, no smoking, no drinking and die in their 30's. Some children get cancer, what's the cause then?
I live in the Detroit area. We are one of the fattest areas in the country. It is hard to believe how many overweight kids and adults are here. We wonder why healthcare is so expensive? We are doing it to ourselves with diabetes, obesity, cancer, and hypertension skyrocketing. Much of this (certainly not all of it) preventable or controllable - and garbage diets being the biggest cause.
I'm not supporting veganism. That is fine for them, but I do like cheese on some things. Genetics is a big part of it and there is no sure fire answer to perfect health.
You can only do what you think is smart with your body.
Meat, hormones are known carcinogens. That is a fact. I may still get cancer someday, but I'm not going to help it get me by living a lifestyle that makes things easiest for it to take hold. Exercise is important as well. I run 30 miles a week and actively participate in 1/2 marathons and 5K/10K races. My marathon days are over.. I have no ill effects in keeping in shape without meat in my diet. Perhaps the vegans you know have other issues.
I choose not to risk it and eat healthy. I'm not a vegan as I eat dairy but am practically a meatless eater. It took a couple years to ween myself off the glorious food as an everyday thing, but it can be done.
This documentary will hopefully be more 'food' to keep me honest.
Health is the primary reason for me in avoiding meat but quality of life and staving off the effects of age for as long as possible is the other reason for eating well. There are many benefits to eating well.