If you don’t eat enough food that contains a certain vitamin, you’ll receive a log message saying you’ve started getting affected by your bad eating routine. For example, if you don’t eat enough meat or food that contains calcium, you’ll get Hypocalcemia, which will be shown as a status effect under your general status tab in the (@)ttibute menu. If you continue undereating the deficiency will get progressively worse, “upgrading” into Weak Bones and later into Frail Bones, all which worsen your natural healing rate or halt it completely.
Other vitamin deficiencies, like B12 Deficiency or Scurvy, have similar effects. Waking up after a night’s sleep helps you understand what your health’s like - if you have a hard time waking up (“You wake up but all you want to do is go back to bed”) the message log will let you know about your health level getting low so you can act accordingly. Alternatively, if you manage to eat healthy and have a balanced diet you’ll get positive log messages (like “Waking up is surprisingly easy today”) meaning everything with your health is fine so far.
I don’t know if there’s an ‘overeating’ variant for each deficiency. I mean, Hypercalcemia is a thing, but I don’t know if it’s in the game. You might only get debuffed for not having enough of one vitamin in your diet but not penalized for having too much of it. Never got to find out as so far I’ve only been screwed over by eating too much junk food and not enough healthy food. It’s possible to have multiple vitamin deficiencies simultaneously.
