The ketogenic diet (KD) has obtained immense popularity that stretches beyond its myriad of clinical applications. KD provides a practical solution to attain body recompositing and meet the weight loss target within a short interval. This review aims to eliminate misinformation surrounding the KD as it has now become a fad diet. All the major scientific evidence revolving around the biochemistry, physiology, and weight loss are compiled. A special section is dedicated to the scientific literature published on the usage of KD in the management of diabetes and neurological diseases such as drug-resistant epilepsy, Alzheimer’s disease, and Parkinson’s disease. Lastly, the short-term and long-term adverse effects with the use of KD are discussed and cautionary contraindications are also listed.