Time for a change

Your body keeps two months of fat in storage and less than one day of carbohydrate, which tells you what it was expecting to run on. Your entire bloodstream holds about one teaspoon of sugar. Any more and an alarm goes off. Your liver and muscles hold perhaps 2,000 calories of carbohydrate. A day, if you sit still. A lean adult carries around 100,000 calories of fat. Six weeks and more, with no further instructions. You store vitamin B12 for three to five years. You store vitamin A for months, in the liver, like every other hunter. You store vitamin D in your own fat, to see you through a winter. You store almost no vitamin C. Scurvy takes about a month. Look at what gets a warehouse. Fat, and the nutrients that come in an animal. Those arrive in gluts. A kill, a feast, then nothing for a week. So the body built somewhere to keep them. Carbohydrate gets a shelf. If none turns up, the liver simply makes its own, and has done every night of your life. There are essential fats. There are essential proteins. The textbook requirement for carbohydrate is zero, and it says so. No engineer builds a 100,000 calorie tank for the reserve fuel and a one day tank for the main one. The plate they drew for you is two thirds the fuel you were never built to store.