Malnutrition results from a deficiency of essential vitamins and nutrients the body and mind need to function properly. Underlying causes could include poverty, decreased mobility that makes obtaining food difficult, mental health conditions, eating disorders and conditions, or food scarcity. The severity and signs of malnutrition, as well as the character's responses to it, will vary depending on its cause and personal factors, such as their health, genetics, and whether they're deliberately avoiding calories or not. For related (though less extreme) information, see HUNGER.

Having little or no muscle tone
Hollow cheeks
Sunken eyes
Thinning or brittle hair
An unfocused gaze
Pronounced bone structures
A character's skin changing in color, texture, or health
A swollen or cracked tongue
Decaying teeth
Bad breath
Wheezing or shortness of breath
A head that lolls, as if it's too heavy to hold up
Slow movements
Having to sit or lie down frequently
Tripping over their own feet; clumsiness
A jerky gait with steps that drag
Visible tremors in the limbs
Stabilizing themselves against walls, countertops, or furniture
Speaking less (lacking the energy to do so)
Slurred speech