Which of these is a symptom of anorexia nervosa?

Hello, you did not give us the symptoms in your question, but below, I will list symptoms of Anorexia:

Whole body: dehydration, dizziness, fainting, fatigue, low blood pressure, low body temperature, osteoporosis, water-electrolyte imbalance, or feeling cold

Behavioral: binge eating, compulsive behavior, hyperactivity, impulsivity, or social isolation

Mood: anxiety, apprehension, or guilt

Weight: underweight, weight loss, or extreme weight loss and thinness

Developmental: delayed puberty or slow growth

Menstrual: irregular menstruation or absence of menstruation

Gastrointestinal: constipation or vomiting

Also common: brittle nails, bruising, depression, dieting, dry hair, dry skin, headache, sensitivity to cold, or slow heart rate

fluid balance is an aspect of the homeostasis of organisms in which the amount of water in the organism needs to be controlled, via osmoregulation and behavior, such that the concentrations of electrolytes (salts in solution) in the various body fluids are kept within healthy ranges. the core principle of fluid balance is that the amount of water lost from the body must equal the amount of water taken in.