Background: Obesity and overweight are global public health concerns with serious health and economic consequences. The ketogenic diet (KD), characterized by high-fat and low-carbohydrate intake, has emerged as a popular strategy for weight loss. Objective: This systematic review aims to assess the effectiveness and safety of ketogenic diets in reducing body weight and BMI among overweight and obese adults. Methods: We conducted a systematic search following the PRISMA 2020 guidelines and PICOS framework. Seven interventional studies met the inclusion criteria, evaluating the effects of various forms of ketogenic diets compared to standard or non-ketogenic diets in adults aged 18–65 years with BMI ≥25 kg/m². The review protocol was registered in PROSPERO (CRD420251017102) prior to data extraction. Results: Across all studies, ketogenic diets led to significant weight loss and BMI reduction compared to control groups. Reported adverse events included mild symptoms such as fatigue, gastrointestinal discomfort, and "keto flu," which were generally transient and manageable. No severe adverse effects were reported. Conclusion: The ketogenic diet appears effective for short- and medium-term weight loss in overweight and obese adults, with mostly mild side effects. Professional supervision is recommended to mitigate potential risks. Further high-quality research is needed to assess long-term effects and metabolic outcomes

Keywords: Ketogenic diet, Obesity, Weight loss, BMI reduction, Diet therapy, Low-carbohydrate diet