Seyfried's Cancer Diet: My Fasting Jump-Start to Ketosis

Cancer cells with title of post "Ketosis for Cancer"

Dr. Seyfried's book, Cancer as a Metabolic Disease, inspired me to attempt a fasting jump-start to ketosis to see how long it takes to achieve his "zone of metabolic management." Read on to see how it's going so far! (I'm still alive . . . )

Note: this post was originally published on Aug 1, 2013. It was edited to streamline content and improve graphics in June 2016; therefore some older comments may pertain to content that was removed during revision.

Dr. Seyfried’s ketogenic diet for cancer

Caution: dietary experiments with fasting and ketosis are best done under medical supervision, particularly if you have a medical condition or take any daily medications. Everyone’s metabolism is different, so results will vary. Please see my post "Is the Ketogenic Diet Safe for Everyone?"

After reading Dr. Seyfried's book, I immediately felt sympathy for those of you out there who have cancer now, or who are cancer survivors worried about recurrence—were you hoping for a simple nutritional strategy, such as "eat more broccoli" or "add chia seeds to your morning smoothie?" Had I led you down a road of hope and then left you feeling disheartened when you saw how difficult Dr. Seyfried's diet appeared to be? Let me try to make it up to you by trying his diet myself while you watch from the comfort of your living room.

Seyfried's fasting jump-start to ketosis

Dr. Seyfried says the fastest way to achieve optimal blood glucose and ketone levels is to begin with a water-only fasting jump-start to ketosis for 3-5 days. Then embark on a low-calorie "ketogenic" diet, aiming for blood sugar levels of 55-65 mg/dL and blood ketone levels of at least 4.0 mM (see article 3 of my cancer series for more details). As a reminder, average blood glucose levels for most healthy people eating a standard diet run between about 70 and 95 mg/dl, and blood ketone levels are usually 0.3 mM or less.

His plan sounded extreme even to me. However, fasting is supposed to be rather comfortable once you get used to it, and ketogenic diets are known for reducing appetite and improving people's sense of well-being in most cases. Thankfully I do not have cancer, but nevertheless, in an attempt to rekindle the hope that some of you may have lost, I thought I'd take one for the team and try his recommendations myself.

Goals of this experiment

  • To see if I can reach Dr. Seyfried's "zone of metabolic management."
  • To see if I can maintain high ketone levels and low blood sugar levels using my mostly-meat diet [standard ketogenic diets tend to rely heavily on high-fat dairy products, eggs, and coconut oil, none of which I tolerate well].
  • To explore the impact of protein: fat ratios, calories, and exercise on ketone and blood sugar levels.
  • To compare urine ketones to blood ketones and see if there is any correlation.
  • To document effect of this diet on mood, energy, concentration, weight, sleep, etc.
  • To document any side effects of this diet.

My N=1 experiment, phase I: fasting jump-start to ketosis

"N=1" refers to an experiment with only one subject (in this case, me). Everyone's metabolism is different, so please take my experience with a big grain o' salt. Please note that, just because Dr. Seyfried suggests that a water-only fast is the fastest way to get into ketosis does not mean that it is required. I also can't say whether faster is necessarily better for your health or easier than a gradual transition to ketosis.


keto-mojo ketone and glucose meterNote on the ketone meter: When I conducted this experiment, the most affordable, accurate ketone meter was the Precision Xtra®. Unfortunately the "affordable" ketone strips cost $2.22 each! I have since found a meter just as accurate, with an array of great features—and the strips are a much more reasonable 99 cents. You can read more about why I recommend the Keto-Mojo glucose/ketone meter on my ketogenic diet and mental health resources page. Because I like their meter and their mission, I've partnered with them to offer my readers 15% off of the purchase of any new meter kit. Just click the link here; no coupon code necessary.

Day 1 (1/31/13)

Day 1 journal entry

Notes: Much easier day than I had expected. Stomach a little growly, slightly lightheaded, minor difficulty concentrating, vision slightly blurry, low energy. Slept well, but had a funny dream about a granola bar—something I haven't eaten in nearly six years! Since exercise confuses things, none for now.

Day 2 (2/1/13)

Day 2 journal entry

Notes: Fascinating that blood sugar this morning was higher than last night, without any food. This may be due to cortisol and adrenaline reactions to falling blood sugar—these hormones kick in when blood sugar falls to pull it back up again. Mild headache in the morning. More difficulty concentrating today—"spacey" would be the right word—but it only affected my efficiency in doing paperwork. I was otherwise fine and able to work a full day, run errands, drive, etc. Sleep was terrible—slept from 10pm to 1:30 am, then wide awake until 5am, then back to sleep until about 7:30 am. Sleep quality itself was very light and dream-filled, but no granola bar visions tonight. I can't believe how much easier this is than I thought it would be—I'm not experiencing distressing levels of hunger or cravings.

Day 3 (2/2/13—Happy Groundhog's Day!)

Day 3 journal entry

Notes: Finally, we have the appearance of (modest) ketones and blood sugar is stabilizing. Concentration was better today, but still not back to normal. Hunger was more noticeable in the morning and afternoon but again, not distressing. Would it have been nice to eat something? Yes, but it didn't preoccupy my mind. By late evening, hunger is stronger, there is a very mild headache, slight lightheadedness, and stomach growling—this may represent blood sugar falling?—but I was productive late into the evening. I am motivated to keep going by 1) intellectual curiosity and 2) hope that once the ketones are nice and high and the blood glucose is nice and low, hunger will disappear and I'll feel great. We shall see! I sure am saving a lot of time and money this week...

How much longer did my fasting jump-start to ketosis last? What happened on Day 4 took me completely by surprise! Read about days 4-7 in the next post in this series "Keto for Cancer: Week 1—My Transition to Ketosis." If you are interested in starting a ketogenic diet yourself, see my online guide: "Ketogenic Diets 101."

Recommended ketogenic diet and cancer resources

  • Cancer as a Metabolic Disease
  • Tripping over the Truth book cover
  • Keto for Cancer book cover

Download your free e‑book:

Download your free guide to refined carbs and get notified of Dr. Ede's latest posts.

Download the E‑book

Go back