The ketogenic diet (KD), containing high levels of fat and low levels of carbohydrates, has been used to treat refractory epilepsy since the 1920s. In the past few decades, there has been more interest in less restrictive KDs such as the modified Atkins diet (MAD). Our aim was to review all evidence regarding the efficacy and tolerability of the KD and MAD from randomized controlled trials (RCTs) in children and adolescents with refractory epilepsy. We reviewed the current literature using Cochrane, EMBASE, and MEDLINE (using PubMed). We implemented predefined criteria regarding dataextraction and study quality. We identified five RCTs that generated seven publications and recruited 472 children and adolescents with refractory epilepsy (≤ 18 years). The primary outcome (seizure frequency reduction (SFR) ≥ 50%) was attained in 35–56.1% of the participants in the intervention group, compared with 6–18.2% in the control group. Our meta-analysis underlined the significant efficacy of the KD compared with the control group: RR = 5.1 (95% CI 3.18–8.21, p