Those with refeeding syndrome are deficient in potassium, magnesium, and phosphorous, and are often deficient in fluid and a vitamin called thiamin. These nutrients are involved in many important body processes. As a result of nutrient imbalances, patients who are suddenly re-fed can have serious complications, including heart problems, breathing problems, impaired mental status, seizures, paralysis, insulin resistance, and bone problems. There have been deaths associated with refeeding syndrome.