Very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is an autosomal recessive disorder of fatty acid oxidation. The majority of patients with VLCADD can be detected through newborn screening (NBS) with elevated levels of the tetradecanoyl carnitine species. An 11-month-old infant, diagnosed with late-onset VLCADD (genotype: T848C/G1322A) through newborn screening at birth, was admitted with emesis, severe lethargy, limpness in extremities, loss of muscle tone and an elevated CK level. He was mistakenly given Ketocal formula (about 8 g/kg per day long-chain fat-over six times his usual intake) instead of his usual Monogen formula for 2.5 days before being admitted. Once admitted, he was started on Monogen and IV (10% dextrose) fluids. He was discharged home after four days in the hospital without any sequelae of this accidental fat loading event. The report highlights several important points about this particular case and more generally about patients with VLCADD detected through NBS: (1) the amount of time in which patients might become severely symptomatic and the nature of these symptoms after fat loading; (2) the time frame for complete recovery after beginning of treatment; (3) the importance of alerting home-care companies and families about formula delivery errors and their repercussions.