Fasting

Refeeding syndrome if severe enough, may result in death

Refeeding syndrome (RFS) is a metabolic disturbance which occurs as a result of reinstitution of nutrition in people and animals who are starved, severely malnourished, or metabolically stressed because of severe illness. When too much food or liquid nutrition supplement is eaten during the initial four to seven days following a malnutrition event, the production of glycogen, fat and protein in cells may cause low serum concentrations of potassium (hypokalemia), magnesium (magnesium deficiency) and phosphate (hypophosphatemia).^[2][3] The electrolyte imbalance may cause neurologic, pulmonary, cardiac, neuromuscular, and hematologic symptoms—many of which, if severe enough, may result in death.

Refeeding syndrome can occur when someone does not eat for several days at a time usually beginning after 4–5 days with no food.^[4]

Stimulants like amphetamines, methylphenidate, and cocaine, along with opiates, contribute to appetite suppression. This can lead to prolonged periods of inadequate calorie intake, mimicking anorexia nervosa. Individuals with drug abuse who begin to reintroduce normal eating habits after a period of malnutrition may be at increased risk for refeeding syndrome.^[5]