Aside from the negative health consequences of eating meat, it is beyond dispute that the meat industry involves extreme cruelty to animals, and is devastating to the environment. While some people may find it "childish" to care about animals (go figure), it is in all of our interests to care about the environment.
Factory Farm Photos . Warning: these are very disturbing.
Treatment of beef cows
Treatment of chickens
Treatment of dairy cows and veal calves
Treatment of pigs
Treatment of egg-laying hens
Treatment of fish
Meat production and the environment #1
Meat production and the environment #2
Meat production and global hunger
If after viewing all of the above, you still want to eat meat, then that is your choice, but at least you will know the ugly truth behind the meat industry and Ronald McDonald's smiling face.