If you are a vegetarian, you are trying to live contrary to nature. Humans evolved to eat meat. this was God's plan all along. If you try to "buck the system" by going against Divine design and 2 million years of evolution, then you are sure to suffer in life. Indeed, the suffering will likely take many forms:
Vegetarians suffer more often from mental health issues.
I'm not alone in this. Though some suggest that the cause-effect relationship may be difficult to prove, nobody denies the fact that there is a direct correlation between vegetarianism and mental health issues.
Vegetarians are typically in poorer health than their carnivorous counterparts.
There's plenty of science to back this one up. There are many ways to defeat the results of a grain-based (vegetarian) diet: Atkins, Paleo, Primal, HFLC, etc. All these diet plans see fantastic success.
Vegetarians are typically liberal.
Conservatives and Libertarians are typically not as likely to self-harm, or live in a state of denial about facts (like the fact that eating meat is good for you!). Often, liberals will become vegetarians due to concerns about animal welfare. While nobody is in favor of animal cruelty, the idea of becoming vegetarian to try to lessen animal cruelty is akin to getting a vasectomy because your neighbor has too many kids.
Of course, to complete the circle, there is a known relationship between liberalism and mental disorder.
Maybe it goes like this sometimes:
Person stops eating meat.
Person gets fat on grains.
Person gets mentally ill.
Mentally ill person decides to become liberal.
Or maybe it goes like this:
Liberal mentally ill person decides to stop eating meat.
Negative effects intensify.