A New York physician who had spent twenty years failing to make fat people thin by starving them walked into the American Museum of Natural History, asked the curators what prehistoric man had eaten, and spent the next forty years prescribing fat meat and water to seventeen thousand patients. Blake Donaldson had done what every doctor did. He had put his heavy patients on low-calorie diets and watched them cheat, give up, or lose weight and put it back. So he went to look at the skulls. The teeth of our ancestors, the museum told him, were the teeth of meat-eaters, and the great weakness of the modern mouth was a sign that the diet had changed faster than the animal. Then an Arctic explorer, fresh from a year on meat in a New York hospital, told him that the Inuit lived well on fat and starved on lean. Donaldson built his prescription from that. Three meals a day of half a pound of fat meat each, three parts fat to one part lean by the calorie, salted, with water and black coffee, and a half-hour walk before breakfast. No flour, no sugar, no milk. His patients lost two to three pounds a week without hunger and kept it off. His allergy patients, he said, lost their allergies. He published it all in 1962 under the title Strong Medicine, with a line that is still quoted: there are probably only two perfect foods, fresh fat meat and clean water. The president of the American Medical Association's journal called the book unscientific. A Harvard nutritionist put it on a list of quackery that should be on nobody's shelves. That nutritionist was being funded by the sugar industry at the time, which emerged fifty years later. Donaldson died in 1966 having spent his whole career doing the one thing the establishment never managed: making his patients thin and keeping them that way. The establishment has spent the years since explaining why he should not have.