The purpose of this review was to understand the impact of second generation antipsychotic (SGA)-induced weight gain on youth with autism spectrum disorders (ASDs), including the clinical evidence, mechanisms, monitoring guidelines, and treatments. To achieve this, multiple MEDLINE/PUBMED and Google database searches were performed and analyzed articles from January 2001 to April 2018. Existing evidences indicates youth with ASDs may be more prone to SGA-induced weight gain than youth with other psychiatric illnesses. The mechanism by which such weight gain occurs is unclear, but is likely multifactorial. Guidelines have been developed to monitor SGA-induced weight gain, though the existing guidelines have had limited adherence by clinicians. The available randomized control trials that have analyzed the benefit of metformin in youth suffering from SGA-induced weight gain have produced conflicting results, but the data looking specifically at youth with ASD have been positive. Increasing data on use of topiramate, melatonin, and zonisamide to treat SGA-induced weight gain in youth also exists and warrants further study. However, overall, the current understanding of the effect of SGA-induced weight gain on youth with ASD and the therapeutic use of medications like metformin is limited, but the existing literature provides useful guidelines for future research. The clinical algorithms for monitoring and managing SGA-induced weight gain have shown promise; however, their utility in routine clinical practice requires further investigation.