Bariatric surgery is increasingly popular as a therapeutic strategy for morbidly obese adolescents. Adolescence represents a sensitive period of psychosocial development, and children with considerable weight loss may experience greater peer acceptance, accompanied by both positive and negative influences. Substance abuse exists as one of these negative influences. We present the case of an adolescent bariatric surgical patient who abused methamphetamines in the postoperative period, with consequent nutritional instability. A concerted effort must be made in the preoperative assessment of adolescent bariatric patients to delineate a history of illicit drug use, including abuse of diet pills and stimulants. Excessive postoperative weight loss or micronutrient supplementation non-compliance should raise a suspicion of stimulant use and appropriate screening tests should be performed. The consequent appetite suppression may manifest with signs of malnutrition such as bradycardia, hypotension, and weakness. Inpatient nutritional rehabilitation and psychiatric assessment should be considered.