because people who eat tons of meat have mineral and vitamin deficiencies because their bodies lose the ability to absorb nutrition properly. the beefed up 300 pound bodybuilder will be b12 deficient, but the skinny vegan you all on here always make fun of won't. 'but steve, meat has b12!'. yeah it does, but just because a food contains a certain vitamin or mineral doesn't mean consuming it covers up for a gut problem, every person i know who is b12 deficient has been eating meat for 20 years. hope that answers your question because a doctor, google, or an internet forum guru sure as hell can't.
how do you get your body to start absorbing nutrition again? fasting and a plant based organic diet. then over time you can gradually add in natural meats like grassfed beef and wild fish etc. you don't just keep eating more and more meat and fix the problem. that would be like spraining your ankle and then running on it everyday, makes no sense.