Ability to hunt
Humans have no claws, out teeth would not render flesh, our mouths are not large enough to catch or wound an animal, nor do we have the speed and reflexes required to ambush and overpower an animal. Humans also lack the basic carnivore instincts: carnivores hunt and tear apart their prey while still alive, and enjoy the smell of blood and raw flesh. On the other hand, humans are sickened by the sight of blood and eat our meat cooked.
Ability to digest meat
When people consume meat, the meat remains in their intestines for significantly longer (24-36 hours, as compared to a few hours for carnivores) due to the larger length and structure of the human intestine. We also do not have the required acidic levels in our saliva and stomachs, essential to break down and digest meat. This results in meat putrefying (meat typically putrefies within 4 hours of consumption) and rotting within our bodies, producing a range of toxins and amines that accumulate in our livers, kidneys and large intestines. These toxins poison our bloodstream, leading to a number of diseases including diabetes, cancers and kidney diseases.