Infection progress has the opposite effect on hunger than is expected. The random drug encounter describes you as (paraphrased) "extremely hungry as the infection converts all food into fluid". The same is noted in the examine self text.
Instead when you are low on infection at the start of the game you will starve in ~24 hours, but get to 75% infection and you can go 5-6 days without eating. The start of the game is extremely hard because of this, you need to get infected as fast as possible and then hope you find the elastic medicine.