The body is meant to function best while eating meat, not vegetables.
It depends on your blood type. I am A and thrive on fruit and veg, indeed. While 0 people can eat meat without any limits. Are you 0?
Therefore, your remark
How many years has human body been accustomed to vegetables vs meat?
is a nice but failed attempt. It could be valid if not for blood types which underwent modification when people started farming on a large scale.
a country in Africa with an almost entirely meat-based diet. Hardly any vegetables at all.
Wow! How is it possible? You probably mean Ethiopia - they love raw meat.