The final transformation of Cleave’s refined-carbohydrate hypothesis into Burkitt’s fiber hypothesis came primarily through the efforts of Burkitt’s colleague Hugh Trowell, who had spent thirty years as a missionary physician in Kenya and Uganda, beginning in 1929. This had been a time, as Trowell later explained, when scores of British doctors working for the colonial service and missionary hospitals in the Kenyan highlands had the unprecedented experience of watching the native population of “three million men, women and children…emerge from pre-industrial life and undergo rapid westernization.” After Trowell retired to England in 1959, he published Non-infective Disease in Africa, which was the first rigorous attempt to draw together the entire body of medical literature on the spectrum of diseases afflicting the native population of Africa.*36 The Western diseases—a list almost identical to Cleave’s—were conspicuous by their absence.

Trowell’s experiences in East Africa had left him with the characteristic awareness of the diseases-of-civilization phenomenon. When he arrived in Kenya in 1929, he said, he had noticed that the Kenyans were all as thin as “ancient Egyptians,” yet when he dined with the native tribes, they always left food at the end of the meal and fed it to their domestic animals, which suggested that their relative emaciation was not caused by food shortages or insufficient calories. During World War II, according to Trowell, a team of British nutritionists was dispatched to East Africa to figure out how to induce the Africans in the British Army to put on weight, since they would not or could not do it. “Hundreds of x-rays,” Trowell recalled, “were taken of African intestines in an effort to solve the mystery that lay in the fact that everyone knew how to fatten a chicken for the pot, but no one knew how to make Africans…put on flesh and fat for battle. It remained a mystery.” Nonetheless, by the 1950s, fat Africans were a common sight, and in 1956 Trowell himself reported the first clinical diagnosis of coronary heart disease in a native East African—a Banting-esque high-court judge (five foot two and 208 pounds) who had lived in England and had been eating a Western diet for twenty years. In 1970, Trowell returned to East Africa and described what he saw as “an amazing spectacle: the towns were full of obese Africans and there was a large diabetic clinic in every city. The twin diseases had been born about the same time and are now growing together.”