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Is Ketosis Necessary On A Low-Carb Diet? Let's Ask The Experts!

Posted Aug 25 2008 6:34pm 1 Comment
One of the most asked about aspects of livin' la vida low-carb has got to the issue of ketosis. There is so much misinformation about there about this very natural state that the body goes through when you are on a low-carb diet (primarily confusing it with a serious condition that diabetics must be careful of called ketoacidosis--NOT the same as ketosis). As such, there may be confusion that lingers out there among my readers who are just learning about this way of eating.

In this recent blog post where I provided some "quickie one-liner" responses to some e-mails, I made the following statement:

Being in ketosis is like being pregnant--you either are or you're not; regardless of what the Ketosticks show you, if you are eating less than 30g carbohydrates a day, then you ARE in ketosis.”

One of my readers named Charles Fred decided to respond to my statement which he disagreed with and it gets to the very heart of this issue about ketosis. Here's what he wrote:

Your statement reflects today’'s informed opinion, but my article in work, “Unified Physiology of the Metabolic Syndrome,” has given me an unusual perspective which for the sake of brevity I’'ll state dogmatically.

Ketosis need not and should not be part of low-carb eating. Low-carb diets should never be labeled as “ketogenic” diets. Ketosis appears to be an “Induction” phase of low-carb eating, but in fact it is a last ditch response to inadequate glucose. As such it is either temporary or avoidable.

Low-carb eating is the evolution-derived diet of humans (unlike other primates). Humans are carnivores, hunters, because human evolution happened pre-fire and pre-agriculture when very few carbs were edible. For carnivores, gluconeogenesis in the liver supplies all necessary glucose.

But if someone abruptly switches from high carbs to very low carbs, gluconeogenesis will be inadequate to supply enough glucose - causing weakness, dizziness and ketosis.

Well if gluconeogenesis is supposed to be adequate, why does it fail? When you eat carbs they are stored as glucose (glycogen) in your glucose fuel tank - your liver. When you manufacture glucose from protein via gluconeogenesis it is stored in that same fuel tank, intermingled with those dietary carbs.

Enzymes, including gluconeogenic enzymes, are expressed only as needed. If your glucose storage is kept full by dietary carbs, expression of gluconeogenic enzymes is reduced. Eventually your gluconeogenic machinery becomes atrophied, inadequate to supply 100% of your glucose requirements.

So, contrary to usual practice, the proper way of switching from high-carb to low-carb is to gradually reduce dietary carbs over the course of about a month, inciting gradual rebuilding of gluconeogenic machinery. Then all those “Induction” woes which convince many that low-carb is not for them are avoided - as is ketosis.

Did you get all that? You'll recall I've explained gluconeogenesis before and it's a beautiful metabolic process that allows your body to make its own carbs (glucose) for the body's needs from the protein you consume through the liver. So, therefore, there isn't a real need for dietary carbohydrate at all.

But Mr. Fred believes eating too few carbohydrates to the point that your body is in a state of ketosis is harmful to your body and that a more gradual progression to lower and lower levels of carbohydrate is needed to keep the body from going through the "shock" of what many describe as the Induction flu . As someone who has gone through this experience and appreciated the benefits of making that "sudden" change, I could not disagree with him more.

What do the low-carb experts have to say, though? I decided to pose this theory put forth by Mr. Fred to several of America's most respected low-carb diet authorities and have them respond:


Not everyone who suddenly moves from a high-carb intake to Induction will get symptoms. Many make the transition very easily. My educated guess is that at least 50% make the transition easily. Others have only mild symptoms. A few have more severe symptoms that can be managed. I think the transition would be easier for more people if they read the book completely so they know what to expect and how to deal with symptoms.

After years in clinical practice I have only had a few patients that required a slow transition because of such severe symptoms. The Induction phase is important especially to those with a severe carb addiction. It is the fastest way to stabilize the blood sugar, control hunger and cravings and improve many diet related symptoms quickly. It is amazing how many people feel better once they are in ketosis by the 4th or 5th day.

Secondly, the mindset of the dieter is they want progress ASAP to stay motivated especially when having to give up some of their favorite foods. Induction provides that. By slowly lowering carbs many will give up too soon and miss the opportunity to find out how effective low-carb can be.

For people with severe health risks, rebalancing the body with a very low-carb intake can lead to rapid improvements in blood sugar, blood pressure, triglycerides and high insulin levels. Until insulin levels improve some of the other benefits of low-carb can't happen. I have seen many severely disordered insulin and blood sugar results that would take far too long to improve with even 60 or 70 grams of carbs.

Just as one diet does not fit all, one level of carb restriction does not fit all. We are all different. The level of carb intake needs to be the level that works for each person based on what we know about them. Dr. Atkins didn't always start in the Induction phase--some people didn't need it, yet many did and would not have been as successful without it.

Unfortunately, many are still stuck in the mindset that having ketones from fat burning is abnormal and undesirable. We know it is not. Dr. Veech, an NIH researcher, agrees that the negatives about dietary ketosis are misunderstood.


Humans are omnivores--able to survive as carnivore, but thrives as omnivore.

Gluconeogenesis isn't solely a metabolic process induced by carbohydrate restriction; it is a normal homeostatic process to maintain blood glucose, so even those consuming a high carbohydrate diet will utilize it as needed (usually when engaged in high levels of activity or during the period of sleep).

The idea that if you don't use it, you lose it, is an incomplete view--yes the enzymes will be made in lesser amounts if one doesn't rely on gluconeogenesis to fully supply glucose, but to claim "atrophy" sets in is a bit over the top.

Some people do find this approach to be a gentler way to restrict carbohydrate--slowly lowering their intake over a period of time; others do better just going "cold turkey" and reducing carbohydrate below 40g. Both reach the same endpoint--persistent state ketosis and utilization of gluconeogenesis. The idea that one will not induce ketosis (burning fat) doing the former is physiologically not possible--if your carbohydrate is below a particular threshold, you're going to make ketone bodies.

The result of reducing carbohydrate slowly isn't a lack of ketone bodies being produced, but less of them wasted, thus the less likelihood a person will register ketosis on Ketostix. Those who restrict carbohydrate below 40g initially make more ketone bodies than necessary, so they "spill" the excess in urine, saliva and sweat. But someone reducing carbohydrate slowly is also making ketones--just less likely to be spilling excess ketones.

With time the person who reduced carbohydrate below 40g and stays there will also begin to not see any measurable ketones on the Ketostix as they get more efficient at making ketones for energy. There is less wasted ketones, thus less to see on the sticks, as time passes. But, if one is keeping carbohydrate below 40g, they're burning fat for their primary energy source, which means they are making ketones whether they register on the sticks or not.


In most medical terminology, "osis" implies "the abnormal condition of"--like onychomycosis means "abnormal nail fungus," halitosis means "bad breath." Perhaps this is one reason why people unfamiliar with low carb approaches jump to the conclusion that "ketosis" is harmful. If you have no insulin in your body, as in Type 1 diabetes, a potentially life-threatening condition called diabetic "ketoacidosis" can occur. My Duke colleague Will Yancy published a paper looking at the pH in the blood of people on two diets (low-carb vs. low-fat) and did not find low blood pH ("acidosis"), but because the blood bicarbonate was lowered below the normal range we called it a "compensated metabolic acidosis." Another published study by Brehm showed the average level of blood ketones goes down over time.

In our clinic, some people always have ketones in the urine, others never do, other fluctuate back and forth. Dr. Atkins used the phrase "benign dietary ketosis" in his books. I have wondered if it would be better to say: "ketosis without acidosis" or "ketonuria" instead of "ketosis." "Ketonemia", which means "ketones in the blood"

"ketonuria", which means "ketones in the urine."

I don't agree with Charles Fred's point of view. You can see why there might be confusion. If you said "if you are eating less than 20g of carb per day then you are burning fat, or in the fat burning zone, or the 'ketone zone'--apologies to Barry Sears and the Zone Diet--rather than "in ketosis," then this might be technically more correct.


This does not make a lot of sense to me. Ketone production and utilization and

ultimately blood and urine levels vary along a continuum. So to suggest it is an

absolute yes or no is not accurate. There is also a diurnal variation and many

other factors that influence their metabolism other than diet (e.g., exercise).

There is also a lot of individual variation in regards to the level of

carbohydrate restriction required to see significant accumulation of ketones. So

I don't see it as black and white.

Gluconeogenesis is more than adequate to supply obligatory glucose needs. How

else would you explain the aboriginal hunting and fishing cultures (e.g., Inuit

of the Arctic and First Nations groups in Canada) who survived for millennia

with little if any identifiable dietary carbohydrate intake? I guess I'm not quite understanding the point of it all.


There is a continuum of ketosis. In fact, one of the features of ketone bodies is that, unlike other fuels, glucose and fatty acids, they can be present in plasma over a wide range of concentrations. What is true is that Ketostix measure ketonuria which may or may not give you an accurate view of plasma ketone bodies. If ketone bodies are used as fast as they are made, you may never see ketosis. Also, I personally think there may be more aspecs of normal ketone body metabolism than we know about now. There is the idea, for example that glial cells may supply ketones as fuel for neurons:

Guzman M, Blazquez C. Ketone body synthesis in the brain: possible neuroprotective effects. Prostaglandins Leukot Essent Fatty Acids 2004;70(3):287-92.

Ketone bodies make an important contribution to brain energy production and biosynthetic processes when glucose becomes scarce. Although it is generally assumed that the liver supplies the brain with ketone bodies, recent evidence shows that cultured astrocytes are also ketogenic cells. These findings support the notion that ketone bodies produced by astrocytes may be used in situ as substrates for neuronal metabolism, and raise the possibility that astrocyte ketogenesis is a neuroprotective pathway.

This theory from Mr. Fred seems to assume that ketosis is somehow foreign or not part of normal metabolism. It is true that it may take some time to adapt to it but there is no reason to assume that it is inherently undesirable. Human evolution probably had a lot of starvation. The function of ketone bodies is to keep gluconeogenesis from having to supply all necessary glucose because it can be a drain on body protein.

I don't think gluconeogenesis fails. There is just some period of adaptation. If there is evidence for Mr. Fred's theory, then I would be interested. Practically, it may feel better to adapt to low-carb slowly--I think it depends on how much carbs you start out with--but the idea you can be on very low-carb and not be in ketosis has to be tested. I personally doubt it but I don't know.

Ketone body production is under the control of many factors: glucose, insulin, fatty acids, level of oxidative metabolism, etc. I think there is also a time factor. Many people eat one meal a day, are quite happy with it and they may be in ketosis at some point during the day. So, it may be useful for some people to get into low-carb slowly but I don't react well when somebody tells me didactically the proper way to eat. "Proper" usually means the way they do it.


I don't agree with this man at all. Your body still produces ketones from all the extra dietary fat, and it gets better at doing that and using the ketones as time goes on. In our work at the University of Connecticut, with three months of following a weight loss ketogenic diet all subjects had a decline in urinary ketones over time even though they were eating the same foods and had the same caloric restriction.

What's happening is that the body is getting better at taking up the ketones--maybe ketone receptor unregulation. Also, they all still had ketones in their blood after three months and this was higher than baseline and much higher than those following a low-fat diet. Your body does not have enough metabolic machinery to produce enough of it's own glucose to support all organs (i.e. your heart).

Yes, it's true gluconeogenesis goes up, but most organs don't use it anyway. That's why blood glucose tends to drift up over time.

Now that the experts have weighed in on Charles Fred's hypothesis, why not share YOUR thoughts based on your own experience following a low-carb diet. Did you ease into livin' la vida low-carb and have excellent results doing it that way? Or did you do like most of us did, myself included, and go from a high-carb to a low-carb diet overnight? Did you see measurable results doing it that way despite having some temporary unpleasantness? Share your thoughts in the comments section below.

Special thanks to all the experts I quoted in this post for sharing their knowledge about this subject of ketosis. On behalf of me and my readers, THANKS SO MUCH! :)

Labels: Cassandra Forsythe , Charles Fred , Eric Westman , gluconeogenesis , Induction , Jackie Eberstein , Jeff Volek , ketoacidosis , ketones , ketosis , regina wilshire , Richard Feinman

Comments (1)
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Hi. My husband and I have had good success with going cold-turkey on the Atkins diet, though we did have a hard week or two at first.

I found your discussion of ketones very interesting. But I have a question: I have benign kidney cysts (I am 62 years old). Will the protein of a low-carb diet such as Atkin's aggravate that? How about the ketones? I cannot find anything on it, and so am not sure if I can return to the Atkins diet now or not.

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