^ This anon knows their stuff.
Saturated (animal) fats = healthy
Unsaturated (vegetable) fats = deathly
Testosterone is made from saturated fats. This is the reason why so many young bucks and well, men in general, are suffering from low libido, erectile dysfunction, lack of muscle and muscle definition, and many other ailments.
After being a vegan for 18 months I did the experiment and suffered greatly. Went down to 120lbs, looked emaciated and got very week, Worth noting that after 18 months of veganism, the first meal with meat I had was fish. The next morning I got a glimpse of myself in the mirror and my muscles within 12 hours looked pumped and I felt energy for the first time in months.
Some people more than others need meat but humans definitely require animal protein to live a healthy and happy life. You can notice how aggressive and almost psychotic vegans become after years and years of their philosophy; they're craving blood. Just shoot a cow and eat it if it means you're going to hate on your fellow human.
I mean I still cheat with soda and fast food time to time but never again will I commit to full on veganism.