First big kudos to the art department!
Sadly the game felt too unforgiving right from the beginning. The color changes of the fireflies happen to quick. Audio (deeply missed) could have helped to understand what is going on intuitively: like a fizzle sound if he burns his tongue. +1 for the suggestion by Oknaa with the fullness bar and transforming the time into seconds. Furthermore: it makes little sense that the fullness meter goes down when he burns his tongue – I’d suggest an additional health bar instead that is affected by the burning (and may slowely decrease when the hunger is too much).