Adults in the United States consume on average around 3,600 kilocalories of food per day,10 mainly in the form of refined starches, proteins, fats, and sugar. This is a good deal more than the recommended 2,000–2,500 kilocalories per day necessary to stay healthy. Despite the tendency to eat more food than is actually good for us, energy from food now accounts for a tiny proportion of the total energy we capture and put to work. But the energy footprint of food production is another matter.
