China's food supply chain has a lot of inefficiencies spread over many small farmsteads with old technology and poor conditions instead of highly mechanized large agriculture farms in the west. I don't remember the exact numbers but lost in harvest, storage, transportation, refining was equivalent to total food imports before it reaches consumers. There's also massive waste in food services, the number is something ridiculous like enough to feed 400 million annually. This was from a study from ~5 years ago.