Problem: Despite widespread awareness of the appropriate countermeasures, obesity remains a major global public health concern. Approach: Ketogenic diets are becoming more popular among various dietary strategies for controlling body-mass and promoting fat mass loss. KD significantly lowers daily carbohydrate intake. Increased fatty acid utilisation follows, which raises blood ketone bodies (acetone, 3-β-hydroxybutyrate, and acetoacetate) and, consequently, metabolic ketosis. Studies on nutritional interventions have traditionally concentrated on lowering dietary fat, but the long-term benefits have been scant or inconsistent. Findings: This review studies the effects of KD on body composition improvements and BM reduction in inactive persons when paired with various exercise modalities (either resistance training or endurance training) in athletes and obese adults. Relevant studies were found by doing a literature search from 1921 to March 2024 using the databases Medline, Google Scholar, PubMed, Web of Science, Scopus, and Sport discus.