Anorexia and bulimia nervosa are characterized by unbalanced eating patterns that include inadequate dietary intake of various nutrients. Conservation mechanisms resulting from starvation and/or self-prescribed nutrient supplements can result in laboratory values that appear within normal limits. These artificially inflated values drop to dangerous levels in some patients once rehydration and refeeding begin. Electrolyte status must be closely monitored during this time to prevent complications. Other micronutrient deficiencies can be corrected with adequate dietary intake, but patients with eating disorders are unlikely to consume such an adequate diet immediately upon entering treatment, so they may benefit from supplementation. Depleted nutrient stores require longer supplementation than acute inadequacies in nutrient intake. This review compiles the findings reported to date regarding micronutrient deficiencies and supplementation for patients with anorexia and bulimia. Because of the widely varying eating practices from patient to patient and the current lack of data controlling for nutrient self-supplementation, nutrition assessment performed by a nutrition professional via food intake history may be more practical than laboratory tests and more accurate than current food intake for determining potential micronutrient deficiencies.