Dietary therapies are established as beneficial for symptomatic generalized epilepsies such as Lennox-Gastaut syndrome; however, the outcome for idiopathic generalized epilepsy has never been specifically reported. The efficacy of the ketogenic and modified Atkins diet for childhood and juvenile absence epilepsy was evaluated from both historical literature review and patients treated at Johns Hopkins Hospital. Upon review of 17 published studies in which absence epilepsy was included as a patient subpopulation, approximately 69% of 133 with clear outcomes patients who received the ketogenic diet had a >50% seizure reduction, and 34% of these patients became seizure free. At Johns Hopkins Hospital, the ketogenic diet (n = 8) and modified Atkins diet (n = 13) led to similar outcomes, with 18 (82%) having a >50% seizure reduction, of which 10 (48%) had a >90% seizure reduction and 4 (19%) were seizure free. Neither age at diet onset, number of anticonvulsants used previously, particular diet used, nor gender correlated with success.