Ketogenic Diets: What Impacts Your Blood Sugar the Most?

Posted September 22, 2015 at 8:00PM

As you may have read in my articles among hundreds of others on the web, there has been a significant amount of enthusiasm recently for the potential metabolic management of cancer. This ranges anywhere from diet (fasting, ketogenic diet, calorie restriction, etc) to metabolic treatments that lower blood sugar and the hormone insulin, which pulls sugar from the blood and into cells.1

Based on a significant amount of preclinical data revealing the reliance of cancer cells on glucose, along with some other studies on key metabolic factors that promote cancer cell proliferation and repair of damage from chemoradiation,2 I have been a huge fan of increasing the research on potential metabolic management, especially through diet.3 Multiple recent studies have revealed that elevated blood glucose levels have a detrimental effect on survival in patients receiving treatment with surgery, chemotherapy, and radiation therapy for brain tumors.4–6 Small studies have shown that a very low-carbohydrate and high-fat ketogenic diet (KD) may potentially offset the elevation in serum glucose of patients being treated with chemoradiation for high-grade glioma.7

I, along with many of my colleagues, am a huge supporter of the theory (is it still a theory?) regarding blood sugar levels and cancer initiation/progression. My colleague and friend, Dr. Rainer Klement, and I recently wrote a rebuttal to a research article that revealed a detriment in survival with elevated blood glucose levels in patients with gliomas. Neither the authors, nor their results make any comments on a ketogenic diet throughout the manuscript, but then caution against it in the conclusions.

A ketogenic diet, even transiently to potentially increase the efficacy of chemoradiation, has been met with apprehension due to many ungrounded issues. Dr. Klement and I had issues with this article’s comments and we wrote a letter to the editor discussing them.8 It apparently sufficiently ticked off the authors, as they wrote a somewhat scathing response.9 We did misquote an article, giving them some free ammo, but their response was definitely charged, further emphasizing the irrational fear of a ketogenic diet and dietary changes in general within the cancer world.

What Affects Blood Sugar the Most?

I have prepared a clinical trial utilizing the ketogenic diet in combination with chemoradiation. It has taken me several years to write and I am still in the implementation phases. During a ketogenic diet, serum glucose levels usually drop significantly and ketone bodies are created by the liver to provide a source of energy that can cross the blood brain barrier to be utilized by neurons. In an effort to assess the difficulties of the diet, I have engaged in it several times in the past in the exact manner that I was planning on having patients follow the diet to make sure that it is doable. Most recently I was on a strict ketogenic diet for one month, performing frequent finger sticks for blood glucose and ketone measurements using a glucometer to assess the effect of different dietary habits on the KD.

I engaged in this self-study under the assumption that dietary intake would lead to the highest blood glucose levels, therefore helping to guide patients on which foods to avoid during the KD. What I found was that the serum glucose levels were not most affected by my intense workouts. This is not surprising as the body mobilizes glycogen to be “consumed” by muscles and we would expect a corresponding rise in blood glucose levels. However, rather unexpectedly, my morning ride to work had the next largest effect.

While the dietary consumption of an array of low-carbohydrate foods appeared to result in little alteration in my blood glucose levels, a 10-12 minute ride to work during the week on average caused the serum glucose to rise from 76 to 98 mg/dl. On multiple occurrences, blood glucose levels rose over 30 mg/dl and by nearly 50%. This was then compared to blood glucose levels on the weekend, which revealed no significant changes throughout the morning in the absence of the daily drive to work. The experiment was then extended to the exact same drive home from work. Serum levels remained minimally changed from this drive.

Final Thoughts

I conclude that the cortisol release from the stressful daily drive to work resulted in a large and significant increase in circulating glucose levels. Previous studies have revealed the effects of driving on stress levels and cortisol release.10 Fast driving may have a worse effect, which certainly contributes during my typical drive to work (something I am trying to work on). Studies have even shown that traffic noise can raise cortisol.11

Dietary efforts to reduce blood glucose levels are currently being tested in multiple clinical trials, including several that are geared toward the cancer patient. Yet, based on my personal experience, it appears that psychological factors, including stress, may have a greater impact on large fluctuations of serum glucose levels and should be addressed in future studies.

To Your Health,


Dr. Colin Champ

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Dr. Colin Champ is a practicing radiation oncologist and nutritional expert. He is the author of Misguided Medicine: The truth behind ill-advised medical recommendations and how to take health back into your hands” You can hear more from him as the host of the incredibly popular Caveman Doctor podcast.


1. Nowak, K, Eldredge-Hindy, H, Champ C. Metformin: The sweet link between tumor genetics and metabolism? OA Cancer. 2014:2(1):7. Accessed October 18, 2014.

2. Klement RJ, Champ CE. Calories, carbohydrates, and cancer therapy with radiation: exploiting the five R’s through dietary manipulation. Cancer Metastasis Rev. 2014:1-13. doi:10.1007/s10555-014-9495-3.

3. Champ CE. Nutritional Approaches for Cancer Prevention and Treatment. Altern Complement Ther. 2014;20(6):302-305. doi:10.1089/act.2014.20604.

4. Derr RL, Ye X, Islas MU, Desideri S, Saudek CD, Grossman SA. Association between hyperglycemia and survival in patients with newly diagnosed glioblastoma. J Clin Oncol. 2009;27(7):1082-1086. doi:10.1200/JCO.2008.19.1098.

5. McGirt MJ, Chaichana KL, Gathinji M, et al. Persistent outpatient hyperglycemia is independently associated with decreased survival after primary resection of malignant brain astrocytomas. Neurosurgery. 2008;63(2):286-291; discussion 291. doi:10.1227/01.NEU.0000315282.61035.48.

6. Mayer A, Vaupel P, Struss H-G, Giese A, Stockinger M, Schmidberger H. Strong adverse prognostic impact of hyperglycemic episodes during adjuvant chemoradiotherapy of glioblastoma multiforme. Strahlenther Onkol. 2014;190(10):933-938. doi:10.1007/s00066-014-0696-z.

7. Champ CE, Palmer JD, Volek JS, et al. Targeting metabolism with a ketogenic diet during the treatment of glioblastoma multiforme. J Neurooncol. 2014;117(1):125-131. doi:10.1007/s11060-014-1362-0.

8. Champ CE, Klement RJ. Commentary on “Strong adverse prognostic impact of hyperglycemic episodes during adjuvant chemoradiotherapy of glioblastoma multiforme.” Strahlenther Onkol. 2014. doi:10.1007/s00066-014-0788-9.

9. Mayer A, Vaupel P, Struss H-G, Giese A, Stockinger M, Schmidberger H. Response to commentary by Champ and Klement: Is a ketogenic diet the solution for the hyperglycemia problem in glioblastoma therapy? Strahlenther Onkol. 2015;191(3):283-284. doi:10.1007/s00066-014-0793-z.

10. Tsopanakis C. Stress Hormonal Factors, Fatigue, and Antioxidant Responses to Prolonged Speed Driving. Pharmacol Biochem Behav. 1998;60(3):747-751. doi:10.1016/S0091-3057(98)00037-9.

11. Prasher D. Traffic noise increases stress by driving up cortisol. Lancet. 1998;352(9135):1201. doi:10.1016/S0140-6736(05)60543-0.



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