When it comes to the overall death toll, for instance, researchers so far have had to extrapolate from official population statistics…Their estimates range from 15 to 32 million excess deaths. But the public security reports compiled at the time, as well as the voluminous secret reports collated by party committees in the last months of the Great Leap Forward, show how inadequate these calculations are, pointing instead at a catastrophe of a much greater magnitude: this book shows that at least 45 million people died unnecessarily between 1958 and 1962.
That is from Frank Dikötter's Mao's Great Famine: The History of China's Most Devastating Catastrophe, 1958-1962, which is one of the scariest books I have read. Here is another passage, I am not sure how well it is sourced:
Mao was delighted. As reports came in from all over the country about new records in cotton, rice, wheat or peanut production, he started wondering what to do with all the surplus food. On August 4 1958 in Xushui, flanked by Zhang Guozhong, surrounded by journalists, plodding through the fields in straw hat and cotton shoes, he beamed: "How are you going to eat so much grain? What are you going to do with the surplus?"
"We can exchange it for machinery," Zhang responded after a pause for thought.
[Showing a poor understanding of Say's Law] "But you are not the only one to have a surplus, others too have too much grain! Nobody will want your grain!" Mao shot back with a benevolent smile.
"We can make spirits of out of taro," suggested another cadre.
"But every county will make spirits! How many tonnes of spirits do we need? Mao mused. "With so much grain, in future you should plant less, work half time and spend the rest of your time on culture and leisurely pursuits, open schools and a university, don't you think?…You should eat more. Even five meals a day is fine!"
Here are some reviews of the book.