Moreover, there is not enough data to decide whether a diet lacking almost completely carbohydrates results in optimal health in the long term, even if it may have favorable effects when replacing a worse previous diet.

Carbohydrates are also the cheapest kind of food. While eating them in excess is bad, obtaining less than 50% of the energy intake from carbohydrates still results in a much lower cost of the food than replacing all of them with expensive fats and proteins.

For diabetes prevention, it is likely that it is more important to avoid sugar than it is to avoid starch, because in many traditional societies where starch was a big fraction of their food, diabetes was nevertheless uncommon.