Obese and morbidly obese patients are a growing group of individuals worldwide that generates immense problems to society. They undergo various interventions that require anesthesia and/or analgesia. Despite their healthy look, these individuals are graded at high ASA physical status, mainly because of their impaired respiratory and cardiovascular conditions, and the metabolic changes their body undergo. Opioids are drugs ubiquitously used for perioperative analgesia. Their use has recently reached a frightening condition worldwide. Multimodal analgesia regimens have been recommended as a perioperative standard care, particularly for the obese. These regimens combine opioids with non-opioid compounds that augment the formers' analgesic potencies. Such protocols provide superior pain relief at rest, movement, or on effort, while reducing opioid consumption and their concerned adverse effects. The most important IV adjuvant currently employed is ketamine that sees resurgence among physicians from diverse medical specialties and for variable pain conditions. This review will summarize obese patients' perioperative drawbacks, will illustrate ketamine¿s neuropharmacology.