For those who asked, I had examined the politics of the Great Leap Forward and the Great Leap Famine in an earlier book Calamity and Reform in China: State, Rural Society, and Institutional Change Since the Great Leap Famine.
https://t.co/0YoQctvNRl
In that book, I relied on demographic estimates made from population data released by the Chinese government in the 1980s. Leading such estimates at the time was Judith Banister, who wrote the landmark volume China’s Changing Population. Based on that data, the Great Leap Famine, with a demographic loss estimated at the 26-30 million range, was easily the worst famine in human history, as measured in terms of total demographic impact.
Note that I was careful to say that the above estimate was based on official demographic data. That data had gone through processing and adjustments. Various local authorities had strong incentives to massage the information and conceal some of the deaths--after all, the dead were no longer available to make their case. It's fair to say that the estimates derived were under-estimates.
Later studies by others, notably Yang Jisheng (Tombstone), have revealed more carnage. Top officials such as Zhou Enlai had also gotten provincial numbers--destroyed--that pointed to larger numbers than what were later derived from the official demographic data.