This is a interesting study of two geographically near tribes of people eating a plant based diet vs a animal based diet.
This type of reporting is rare, since the western diet has changed every group of humans it has contacted.
https://doi.org/10.1001/jama.1931.02730200061030
Full text: https://babel.hathitrust.org/cgi/pt?id=coo.31924003510108
This is a contribution to knowledge concerning the relation of diet to physique and to health. The two tribes selected for this investigation were chosen because of the fact that, although their territories were adjoining, their dietary customs were different, "the Akikuyu being almost exclusively vegetarian and the Masai chiefly carnivorous." The field work in this investigation covered such categories as chemical analysis of all foods in common use, articles of diet in the raw state, cooked foods, edible earths, physical examination of both adults and children, and clinical observations. Additional features of this study pertain to laboratory and hospital work dealing with the adequacy of hospital and prison diets, the effect of additions to the diet of various seemingly desirable supplements, feeding tests with prescribed diets on four groups each of forty boys, and blood studies dealing particularly with calcium and phosphorus content, sugar tolerance, ph and alkali reserve,
Masai
Akikuyu
It should be noted the Masai are not totally carnivores. "Various roots and barks are used to make infusions which are used either with boiled meat or with milk". "The rest of the population, in addition to these four items, which form the main part of their food, eat also some bananas, beans, millet, arrowroot, maize, sugar and honey, as these are available. The use of maize, which was introduced only a few years ago, is increasing." "In periods of severe drought, when, in spite of the large herds, the milk supply is inadequate, the consumption of these vegetable foods is increased".
So the observations of this are not carnivore vs vegetarian, its a meat heavy diet (ASF) but with lots of noise.
One section of the (Masai) tribe, the Loitokitok, have adopted a frankly mixed diet. It is of interest that pica among the Masai is confined to this section"
Appendix 3 - graph 11 - "those accustomed to a vegetarian diet, chiefly carbohydrate, showed a lag in the rate of return to normal after ingestion of glucose".