Ketogenic diet
Also called: keto, low-carbohydrate high-fat diet.
Last reviewed 2026-09-16. How this works.
Treating cancer Grade C
Human evidence exists and does not settle it.
This diet has been tested in people with brain tumours, and the trials did not find that it helped them live longer.
Randomised data exists, and the trial that could have shown a benefit missed its endpoint.
The claim
The claim is that tumour cells depend on glucose in a way normal cells do not, so a diet that shifts the body onto ketones starves the tumour while the rest of the body carries on.
What it does
The idea has a real basis in cell biology and it is not fringe. The difficulty is that reaching and holding the intended state is hard outside a controlled setting, and reviews of the trials report that the intended glucose levels were seldom reached except during fasting periods.3
The evidence
The first trial in recurrent glioblastoma was a pilot with feasibility as its primary endpoint, not survival. Most people reached ketosis at least once. Three of twenty stopped because they could not tolerate it. One minor response was recorded.1
The trial that followed, ERGO2, randomised fifty people to a calorie-restricted ketogenic approach alongside repeat radiotherapy. It did not meet its primary endpoint of improved progression-free survival against a standard diet.2
A systematic review of twenty-three studies covering 306 people found two randomised controlled trials among them, and those trials showed no significant difference in overall or progression-free survival against controls. One in five people dropped out, mostly because of how restrictive the diet is.3
A separate meta-analysis reports a much larger survival figure, but it compares people who stuck to the diet against historical controls rather than against a randomised comparison group. That design cannot separate the effect of the diet from the effect of being well enough to stick to it.4
A further controlled trial, KETOCOMP, is not randomised, and its survival results were reported in a preprint that had not completed peer review. A randomised trial in ovarian and endometrial cancer did report favourable effects, but its endpoints were physical function, energy and food cravings, not what the tumour did.56
The studies this rests on
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ERGO, ketogenic diet in recurrent glioblastoma1
A trial with no comparison group, open label, phase 2, measured safety, 20 participants.
a feasibility pilot; one minor response recorded, three people discontinued for poor tolerability.
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ERGO2, calorie-restricted ketogenic diet with reirradiation in malignant glioma2
A randomised trial, open label, phase 2, measured a clinical outcome, 50 participants.
did not meet its primary endpoint of improved progression-free survival against a standard diet.
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Ketogenic diet in women with ovarian or endometrial cancer6
A randomised trial, open label, measured what patients reported.
favourable effects on physical function, perceived energy and food cravings; tumour outcomes were not endpoints.
What is absent
Outside brain tumours, no randomised trial in this record measured what the cancer did. The trial in ovarian and endometrial cancer measured how people felt and functioned, which is a different question honestly asked.
Scope: cancers other than malignant glioma.
Established by trial scope, checked 2026-09-16. Result: the only randomised trials with tumour endpoints in this record are in malignant glioma.263
What to ask
Would a diet this restrictive cause me problems alongside the treatment I am having?
The dish-to-person gap
This is a way of eating rather than a compound that reaches a concentration in the blood, so the dish-to-person comparison does not apply to it.
When to call your team — no warning signs are recorded
If you have changed how you eat because of something you have read, or are thinking about it, the people treating you can only weigh that if they know about it. That is true when nothing has been written down here, and it is most true then.
The register records no warning signs for this entry. The trials here report that the diet was hard to stick to rather than that it injured anyone, and that is a different finding.
Interactions
A way of eating is not checked against treatment classes in this register. Anyone on a restrictive diet during treatment should tell the team looking after them, because it changes what they are working with.
The whole interaction list, and how to turn it into a pharmacy review request.
Find a trial instead
Several trials have run and more may be recruiting. A trial provides the monitoring that a diet attempted alone does not.
Search ClinicalTrials.gov for recruiting studies of ketogenic diet OR ketogenic
A trial is the same decision with monitoring, a known preparation and a doctor who knows what else you are taking.
References
Rieger J, Bahr O, Maurer GD, et al. ERGO: a pilot study of ketogenic diet in recurrent glioblastoma. International Journal of Oncology 2014;44(6):1843-1852.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 7 note 1. The author string is abbreviated in the source that was read and has not been expanded.
Voss M, Wagner M, von Mettenheim N, et al. ERGO2: a prospective, randomized trial of calorie-restricted ketogenic diet and fasting in addition to reirradiation for malignant glioma. International Journal of Radiation Oncology, Biology, Physics 2020;108(4):987-995.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 7 note 2. The author string is abbreviated in the source that was read and has not been expanded.
Ketogenic diet in the treatment of malignant gliomas: a systematic review. 2026. PROSPERO CRD42024547388.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 7 note 3.
Efficacy and safety of ketogenic diet in glioblastoma: an updated systematic review and meta-analysis. 2026. PROSPERO CRD420251232650.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 7 note 4.
Held against this source and not confirmed:
median overall survival of 29.4 months against 14.6 months
The comparison is against historical controls and is restricted to people who stuck to the diet. Both features are recorded here because the figure is meaningless without them.
KETOCOMP study protocol. Klement RJ, Sweeney RA, Clinical Nutrition ESPEN 2016;12:e1-e6.
doi:10.1016/j.clnesp.2015.11.001
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 7 note 5. The author string is abbreviated in the source that was read and has not been expanded.
Favorable effects of a ketogenic diet on physical function, perceived energy, and food cravings in women with ovarian or endometrial cancer: a randomized, controlled trial. Nutrients 2018;10:1187.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 7 note 6.