China had, since the 1860's, been referred to as the "sick man of the far east", a play on words from a common monicker for I think one of the tzars.
Mostly, this referred to the Qing government, in terms of the extensive corruption, pervasive opium addiction (thanks in part to Britain and the opium wars), etc.
Poor people rarely had much to eat to begin with, and bad years would often mean normally thin meals would be stretched too far. Until the communist revolution, farmers were serfs. After, they operated in collectives, but still were under orders. In both cases, they had little incentive to work, as they didn't keep the food they grew. It belonged to someone else. 1 in 3 children nationwide had stunted growth from malnourishment, almost certainly worse in the countryside. Farmers simply didn't have a surplus of food to store through an entire bad season.
After the 1970s, a combination of infrastructure projects which improved irrigation, some new cultivars of plants that had better yields, and changes to the operations of the farming communes to operate a bit more capitalistically, farmers were able to generate actual surpluses of food.