Infiltrative gliomas are the most common neoplasms arising in the brain, and remain largely incurable despite decades of research. A subset of these gliomas contains mutations inisocitrate dehydrogenase 1(IDH1mut) or, less commonly,IDH2(together called “IDHmut”). These mutations alter cellular biochemistry, and IDHmutgliomas are generally less aggressive than IDH wild-type (IDHwt) gliomas. Some preclinical studies and clinical trials have suggested that various forms of a ketogenic diet (KD), characterized by low-carbohydrate and high-fat content, may be beneficial in slowing glioma progression. However, adherence to a strict KD is difficult, and not all studies have shown promising results. Furthermore, no study has yet addressed whether IDHmutgliomas might be more sensitive to KD. The aim of the current study was to compare the effects of a unrestricted, cycling KD (weekly alternating between KD and standard diet) in preclinical models of IDHwtversus IDHmutgliomas.In vitro, simulating KD by treatment with the ketone body β-hydroxybutyrate had no effect on the proliferation of patient-derived IDHwtor IDHmutglioma cells, either in low or normal glucose conditions. Likewise, an unrestricted, cycling KD had no effect on thein vivogrowth of patient-derived IDHwtor IDHmutgliomas, even though the cycling KD did result in persistently elevated circulating ketones. Furthermore, this KD conferred no survival benefit in mice engrafted with Sleeping-Beauty transposase-engineered IDHmutor IDHwtglioma. These data suggest that neither IDHwtnor IDHmutgliomas are particularly responsive to an unrestricted, cycling form of KD.