You may have heard from your doctor that ketosis is a life-threatening condition. If so, your doctor is confusing diabetic ketoacidosis (DKA) with nutritional ketosis, or keto-adaptation.
First, some semantics. Our body can produce, from fat and some amino acids, three ketone bodies (a “ketone” refers to the chemical structure where oxygen is double-bonded to carbon sandwiched between at least 2 other carbons). These ketone bodies we produce are: acetone, acetoacetone, and beta-hydroxybutyrate (B-OHB). [For anyone who is interested, they are the 3 most right structures on the figure, below.]
Why do we make ketones? For starters, it’s a vital evolutionary advantage. Our brain can only function with glucose and ketones. Since we can’t store more than about 24 hours’ worth of glucose, we would all die of hypoglycemia if ever forced to fast for more than a day. Fortunately, our liver can take fat and select amino acids (the building blocks of proteins) and turn them into ketones, first and foremost to feed our brains. Hence, our body’s ability to produce ketones is required for basic survival.
What is diabetic ketoacidosis? When diabetics (usually Type I diabetics, but sometimes this occurs in very late-stage, insulin-dependent, Type II diabetics) fail to receive enough insulin, they go into an effective state of starvation. While they may have all the glucose in the world in their bloodstream, without insulin, they can’t get any into their cells. Hence, they are effectively going into starvation. The body does what it would do in anyone – it starts to make ketones out of fat and proteins. Here’s the problem: the diabetic patient in this case can’t produce any insulin, so there is no feedback loop and they continue to produce more and more ketones without stopping. By the time ketone levels (specifically, beta-hydroxybutyrate) approach 15 to 25 mM, the resulting pH imbalance leads to profound metabolic derangement and the patient is critically ill.
But this state of metabolic derangement is not actually possible in a person who can produce insulin, even in small amounts. The reason is that a feedback loop prevents the ketone level from getting high enough to cause the change in pH that leads to the cascade of bad problems. A person who is said to be “keto-adapted,” or in a state of nutritional ketosis, generally has beta-hydroxybutyrate levels between about 0.5 and 3.0 mM. This is far less than the levels required to cause harm through acid-base abnormalities.
Keto-adaption is a state, achieved through significant reduction of carbohydrate intake (typically to less than 50 grams per day) and moderate protein, where the body changes from relying on glycogen as its main source of energy to relying on fat. Specifically, the brain shifts from being primarily dependent on glucose, to being primarily dependent on beta-hydroxybutyrate. This has nothing to do with what a diabetic patient is experiencing in DKA, but does illustrate how poorly informed and quick to react the medical community is. DKA and nutritional ketosis (or keto-adaptation) have as much in common as a house fire and a fireplace.
Hi Peter
My husband started the keto diet to lose weight. After trying many different diets, this one finally worked and he lost about 40 lbs. He has been on it for a few years now and is very committed. I started researching the diet to make sure it is safe and healthy long term. After what I’ve read, I have just one question: how does such a diet effect the kidneys? If someone only has about 120% kidney function rather than a full 200%, will ketosis put too much of a strain on the kidneys?
Great article. I agree that the ketogenic has many benefits but at the same time if we limit carbs to less than 50g/day we might end up with a very low fibre diet. I think the great problem is that ketogenic diets can be extremely variable e.g. massive variations in the content of fatty acids and even fibre they may have.
I worry is that some individuals may follow ketogenic diets extremely low in fiber and this may increase their risk of colorectal cancer in the long-term. Furthermore, if these diets are very high in saturated fatty acids they could have a negative action on lipid profile. What do you think about this?
I have been on the keto diet with an occasional (one day every month or so) carb glut for a day or two. My colon works better than in all my life. Because my husband is on the MAD diet for seizure control. I mostly adhere to the same 20grams of carb a day that he must. Your correct, I get little fiber, yet gone, is the lifetime of constipation and gas and gastric reflux and occasional episodes of nausea and vomiting. Flatulence is a thing of the past. I have been assured by a surgeon that many
older folk do better with less fiber. We do eat a bit of kale, radishes, celery, lettuce, super greens, avocado ang a few others, cacao, flax, almond meal. A few walnuts and pecans.
I am a 59 year old and have been diagnosed with Non Alcoholic Fatty Liver Disease. Will a ketogenic diet stress my liver, with the increased fat intake?
Hi Dr. Attia, I found you through the Tim Ferris podcast and have found your blog wonderfully informative.
My question is whether you are aware of causes for dangerously large spikes in triglyceride and LDL-p values while following a strict ketogenic diet high in saturated fats. Are you aware of any specific genes or conditions that could contribute to such a reaction? I’m having trouble finding any information on related cases.
I never stop being surprised at the medically trained people who can’t distinguish between ketoacidosis and dietary ketosis. Just a week ago I spoke to a retired college professor of nursing who instantly assumed I meant the former when I began relating my experiences with the latter.
Hi Dr. Attia, After diagnosis with and treatment to rid myself of a severe Duodenum Ulcer I was the discovered that I have a Hiatus Hernia. My doctor prescribed tablets called Nexium which serve to reduce the amount of stomach acids thus reducing the reflux and pain. I find I need to take one tablet approximately every 3 to 4 days.
If Ketosis produces acid that eats fat rather than Glucose would this acid be detrimental to my condition?
I’ve been using this ketogenic diet, specifically the Cambridge diet for 3-4 weeks now and I have lost 11 kilos. My problem is that my triglycerides are very high (600) and my cholesterol too. Is this diet connected to these side effects? Thank you in advance
Hi Dr Attia,
I have been experimenting with the keto diet for a couple month and have lost about twenty pounds. I love the way of eating and how I feel when eating high fat low carb. But I am currently not following the diet due to finding out I am pregnant. I have heard it isn’t safe to be in ketosis when pregnant. I was wondering what your thoughts are on this? Thank you so much!
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