Nor fat, nor carbs are an essential nutritional component. The body can not synthesize certain amino acids, but it can convert protein to both fat and carbohydrates by means of gluconeogenesis. If anything, we should have cravings for sources of protein, not sugars. One could argue that sugars provide the burst of energy for the metabolic pathway that could be make it or break it in cases where that burst gives an advantage. This, and not the scarceness argument, which seems just thin to me, although mainstream opinion.
jsky_goog|5 years ago
The very rough gist is that there is historical evidence of pre agrarian humans starving to death with stomachs full of lean meat. In a nomadic lifestyle where they chase down prey protein costs too much energy to digest and convert into usable energy.
1_player|5 years ago
Carbs are not essential. You can live on zero total grams of carbs.
Also gluconeogenesis only converts proteins to glucose, not fat, at least not directly.
yourkin|5 years ago
believe it or not, by your definition carbs are also essential, it’s just that the body can produce them
Protein -> carbs by gluconeogenesis
Isoleucine and phenylalanine are exclusively ketogenic and produce ketone bodies.
Leucine can be used to synthesize fatty acids in adipose tissue.
The only 2 fats that we really need are omega-3 and omega-6, but not in huge amounts, thankfully, both not from meat.
Point is, one can more readily survive without a major source of fat or carbs.