Achieving ketosis by engaging in a very low-carbohydrate, high-fat lifestyle is an effective means of losing weight, breaking insulin and leptin resistance, reversing type 2 diabetes and fatty liver, reducing blood pressure, reversing the inflammation of visceral fat, and may even cause partial or total remission of selected cancers.

So what’s the problem?

The problem comes when people remain ketotic for extended periods. We know with confidence that long-term ketosis poses substantial risk for health complications because thousands of children have followed ketogenic diets over the years as a means of suppressing intractable grand mal seizures unresponsive to drugs and procedures, seizures that can lead to irreversible brain damage if not stopped. A ketogenic diet reduces seizures by approximately 55-85%. Because seizures are a chronic problem, these kids maintain ketosis for months to years.

The health of these kids have been formally tracked. What happens to them beyond the reduction in seizures? A number of phenomena emerge:

  • They have high likelihood of calcium oxalate and uric acid kidney stones–Likelihood is 10- to 100-fold greater than in kids not on the diet. Kidney stones are uncommon in childhood, yet these kids commonly have kidney stones. The risk in an adult on a prolonged ketogenic effort is therefore high, also. Kidney stones are not benign–they are painful and can occasionally result in kidney damage (increased creatinine, urinary tract infections, etc.)
  • Growth is stunted–Most of these kids fail to grow normally and fall into the 10th percentile for growth or less. Adults on a ketogenic diet are no longer growing, of course, but the growth impairment observed in children suggests that there is something fundamentally wrong with prolonged ketosis sufficient to impair normal growth.
  • There are occasional instances of cardiomyopathies (heart muscle diseases, heart failure) and sudden cardiac death–The immediate causes are unclear, though at least some cases are due to severe selenium deficiency. The picture is muddied by the fact that some kids are fed large quantities of corn oil as a means of maintaining ketosis. Nonetheless, it suggests further uncertainties with prolonged ketosis.
  • Constipation is the rule–as virtual elimination of dietary carbohydrates also means virtual elimination of prebiotic fibers that nourish bowel flora. Over time, this leads to metabolic distortions including a drop in HDL cholesterol, rise in triglycerides, rise in small LDL particles that lead to heart disease, rise in insulin resistance and blood sugar, rise in blood pressure, even if these parameters initially improved on the diet. This is also due to dysbiosis and lack of prebiotic fibers. While this has not yet been tracked in children, in adults we can expect that these distortions in bowel flora will, over time, also lead to heightened inflammation (bowel and elsewhere), diverticular disease (.e.g., diverticulitis), and colorectal cancer. Yes: prolonged ketosis can add substantially to risk for colon cancer. Other peculiar gastrointestinal complications of prolonged ketosis have also been observed, such as protein-losing enteropathies.

While many of the problems that develop with prolonged ketosis may be addressed simply by minding intake of prebiotic fibers, not all are, such as selenium deficiency and stunted growth.

If you want to use a ketogenic diet as a health tool, it would be wise to do so for no more than a few weeks at a time, as nobody knows how long is too long. And, of course, the period of time during which ketosis is safe can vary from individual to individual. Breaking ketosis is as easy as upping protein intake or having a glass of wine or whole piece of fruit.

Like the stress response, ketosis is a natural, physiological adaptation designed for short-term responses. In other words, an acute stress response to some danger or threat that involves increased adrenaline and cortisol release, increased heart rate and blood pressure, and heightened alertness is normal and can even save your life. But, if the stress response becomes chronic, as it may with divorce, prolonged caretaking of an impaired child or demented adult, PTSD, financial struggles, etc., then the stress response can have terrible health implications that include increased risk for Alzheimer’s dementia, heart disease, dysbiosis, inflammation, diabetes, and cancer. The same applies to ketosis: Acutely, ketosis is a normal physiological adaptation that serves us during periods of carbohydrate or calorie deprivation. Chronically, however, peculiar things happen with consequences that range from constipation, to selenium deficiency and cardiomyopathies, to colon cancer.

Another one of my concerns long-term is that many people are being persuaded to remain on a ketogenic diet over a long period. In 3, 5, or 10 years, we are going to see a sharp rise in colon cancer cases. People in conventional dietary circles will then point fingers at all of us engaged in unconventional dietary advice and we will be lumped together and labeled as dangerous fads. The key is to be smarter and to view ketogenic dieting as the short-term tool/response it is, not as a solution to all health struggles.

Also, be aware that, while diet can be an extremely powerful tool to regain control over many aspects of health, diet by itself remains insufficient for full health. Just as filling up the gas tank of your car with quality gasoline helps your car run well, but other aspects of your car need attention over time (change the oil, tune-ups, new tires on occasion, etc.), so it goes with diet. We must also pay attention to vitamin D and iodine status, the potential for common endocrine disruptions such as thyroid dysfunction, efforts to cultivate bowel flora, and other issues. Focus on diet as a start, not as an end.

So be ketotic—but just don’t stay ketotic for too long. Like an acute stress response, use it to your advantage but don’t allow it to become a chronic impairment of health.


I’d like to share some concerns I have about all the people who are coming to me saying that they’ve been on ketogenic diets for extended periods. Now, let me be absolutely clear, there’s nothing wrong with being ketotic or being on a ketogenic diet — for limited periods of time, and let me tell you why.

First of all, think of being ketotic as like having a stress response. A stress response is a natural physiologic process, right? If something dangerous or life-threatening is about to happen to you, you want to have the increase in heart rate, blood pressure, alertness — for safety. A stress response is a good thing. It’s a protective mechanism.

But what if you had the stress response 24/7; for extended periods, months, or even years on end? That’s what happens, right, when people are stressed to high levels like grief, the death of someone close to you, financial ruin, divorce. When stress goes on chronically, bad things happen. It gives rise to heart disease, cancer, diabetes, other bad effects, dysbiosis that changes bowel flora. Chronic stress, the stress response acutely, is a good thing. It’s a normal protective physiologic response. Chronically, for prolonged periods, it’s a very destructive process.

Ketosis is the same way. For brief periods of times, up to weeks, it’s healthy. It’s wonderful. It helps accomplish such things as accelerate weight loss, accelerate reversal of Type II diabetes, drops haemoglobin A1c, faster reversal of insulin resistance. It helps reverse fatty liver (often to normal), reduces blood pressure, reduces triglycerides — lots of wonderful effects of being ketotic. Problem: being ketotic too long; being on a ketogenic diet too long leads to adverse effects.

Here’s an area where we have good confidence in knowing that prolonged chronic ketosis is bad for you. There are children, kids, who have intractable seizures, grand mal seizures, unresponsive to drugs or sometimes even surgery. They’re put on a ketogenic diet, so of course, very low-carb, very high fat, and they have about 80% reduction seizures. It’s very successful, but kids who remain on this, on a ketogenic diet for a year, two years, three years, start to show bizarre effects — they have at least a tenfold increase in kidney stones, both calcium oxalate kidney stones, and uric acid kidney stones. These are kids who aren’t supposed to get stones at all. So the risk in adults is likely substantially even higher.

Kids have stunted growth. They often fall into 10th percentile. They don’t grow normally. They’re all real short. You and I am not growing, so that’s not a concern, but the fact that kids fall off the growth curve and experience a stunted growth process suggests there’s something fundamentally wrong with the diet, and no one knows what that is exactly.

Then there are the metabolic distortions of dysbiosis. When you fail to take in prebiotic fibers, and don’t make other efforts to restore or maintain healthy bowel flora, weird stuff happens. We’ve seen this happen over and over again in people on ketogenic diets; Atkins, ultra low carb diets, etc. People who do this typically have by a year, two years, or so, sometimes longer: HDL cholesterol drops, triglycerides start to climb back up (even if they’d dropped substantially at the start), small LDL particles on lipoprotein analysis — increase. Postprandial (after meal) distortions develop. Insulin levels go higher. Insulin resistance gets worse. Fatty liver can come back. Blood pressure goes up. You start to get constipated. You develop diverticular disease, and diverticulitis — and down the road, colorectal cancer.

These are not small matters. These are big deals, and this is what happens when you follow a ketogenic diet chronically.

Some of this can be addressed simply by paying to dysbiosis and cultivating healthy bowel flora, with, for instance, a high potency multi-species probiotic, lactate fermented foods, and prebiotic fibers. But a lot of people on a ketogenic diet have not been told this. They have assumed or dismissed the importance of bowel flora, which is a very foolhardy, because you could end up in, who knows, three years, five years, ten years, with a nice case of colon cancer.

One of my fears is that when this starts to happen, when the hundreds of thousands or millions of people following these diets develop bad effects, such as colon cancer, and other metabolic distortions, and diverticular disease, conventional thinkers will say: “see we told you all those fad diets don’t work and they’re gonna be dangerous” they’re going to label more rational approaches, like our approach, the Undoctored or the Wheat Belly approach as just a fad, when it’s not.

We have already incorporated, we’ve accommodated to the reduction prebiotic fibers by adding back prebiotic fibers, and we don’t stay ketogenic for extended periods. Being ketotic, following a ketogenic diet, is fine, but just like a stress response, don’t do it too long. Nobody knows how long a time is too long, but I think it’s probably a matter of weeks and then you should go off. Becoming non-ketotic is as easy as having more protein — having maybe an extra few bites of steak, or fish, or chicken, or having a glass of wine. For many of us, that’s all it takes to break the ketotic process. We’re not talking about going back to cupcakes and candy. It just means not purposely maintaining around-the-clock 24/7 365 days-a-year-ketosis, because bad things will happen if you do that.