Duplicants eat cooking ingredients while finished meals available in the same storage. In addition, it would be great if they eat items with shortest time before spoil first.
Ceterum censeo bugs involving loss of resources mass like pumps, plumbing, water going downhill by steps, airlock doors in a row and so on should be attended with priority as affecting fundamental aspects of the game.
Steps to Reproduce
This issue has not been confirmed by a developer yet.