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Ice Bath for Fast Keto

Updated: Apr 20

Cold plunge stimulates endogenous ketone production

Bearded man with white-rimmed glasses is smiling while immersed up to his neck in ice water.
Dr. Bryan Call demonstrates whole body cold water immersion in his Prism Forge.


  • Although ketosis has a bad reputation, it is a safe & healthy metabolic correction for everyone but Type 1 diabetics.

  • It usually take 3 days of low carbohydrate fasting to reach ketogenesis.

  • An ice bath can stimulate endogenous ketone production immediately.

  • Some brain cells prefer ketones for fuel, even when you're not in full ketosis.

  • Ketones have been shown to improve mental health.

NOTE: Nothing in this article constitutes medical advice. Consult with your medical professional about the risks and benefits of cold plunge therapy that may apply to you.

Is keto safe?

Why do people say keto can be dangerous?

My first experience with ketosis was in December 2001, when my 6 year old son was diagnosed with Type 1 diabetes. I knew nothing about metabolism, about blood glucose, about insulin, about free fatty acids, and I had never heard of plasma ketones.

My ignorance almost killed my son.

Type 1 diabetes (T1D), also called juvenile diabetes, is an autoimmune disorder that causes the body to destroy the islet cells in the pancreas that produce insulin. No one knows why the body attacks itself, although it is now understood that Vitamin D deficiency in the first year of childhood is a significant risk factor for later development of T1D.

Because my son was born in October in northern New York where there was precious little sunlight, it stands to reason that he was Vitamin D deficient the first six months of his life.

Six years later, when he was admitted to the hospital with full-on T1D, his blood sugar was over 700 mg/dL (about seven times a healthy level). Without insulin to carry glucose from his bloodstream into the cells of his body where it could metabolized for energy or converted into white fat, the only mechanism for clearing glucose from his body was thru his urine.

And he couldn't pee fast enough to rid his body of the sugar in the fruit juice I was feeding him. I thought he had the flu, and that the Vitamin C in orange juice would do him some good.

I was wrong.

But it wasn't necessarily the fruit juice that was about to kill him. More serious was the fact that his body, in a desperate attempt to keep his glucose-starved cells alive, was producing massive levels of ketones.

In his new book, Ketones, the 4th Fuel (2020) science journalist Travis Cristofferson describes how the body obtains energy from four different types of food: 1) carbohydrates, 2) fats, 3) protein, and 4) ketones.

The first three types of food are abundant. Carbohydrates include simple sugars (e.g., fruit juice) and more complex grains, fats and protein are found in meat, fish, nuts, and some seeds, but ketones are unusual in a normal diet. Some biohackers consume coconut oil, or medium-chain triglycerides (MCT) to boost their ketone levels, but for the most part ketones are only in the bloodstream when they are synthesized in the liver to provide fuel when glucose is scarce.

In people without T1D, a low carbohydrate diet will cause white fat cells to release free fatty acids into the bloodstream, where they are converted to ketones in the liver, and transported back through the bloodstream to muscle and other cells for the rapid conversion into energy. That's why a ketogenic diet is so effective for fat loss. Switching your metabolism into ketosis will cause the white fat cells in your body to shrink, resulting in a leaner body composition.

Ordinarily, healthy blood glucose levels are maintained during ketosis -- even on zero carbohydrate diet -- by a process called gluconeogenesis, in which the liver (and kidney) form blood glucose from non-carbohydrate sources (Berg et al, 2002). However, in my son's case, glucose was abundant in the bloodstream but unavailable inside his cells, because he was not making enough insulin to carry the glucose from his blood across his cell walls.

To compensate for the lack of energy inside each cell, his liver was working overtime to produce more and more ketones -- so many that the concentration of ketones began to lower the pH of his blood to a life-threatening condition called ketoacidosis.

When he was admitted to the pediatric intensive care unit, our doctor told me that he was hours away from a deadly coma. As they dripped insulin into his bloodstream overnight, I watched him slowly return to health during his sleep. Every hour brought a visible improvement in his condition, until he woke up in the morning and, for the first time in days, declared "I'm hungry."

I wept.

Then I got him some scrambled eggs, which he devoured.


Ketosis is healthy

It is the life-threatening condition of ketoacidosis that has created the impression among some nutritionists and medical doctors that ketosis is dangerous. However, in people with healthy insulin levels, ketosis is not dangerous at all (Ludwig 2020). Because gluconeogenesis maintains stable blood glucose levels that prevent glucose starvation inside the cells, when insulin is present ketone production remains regulated to levels that remain far below ketoacidosis.

In fact, more and more people are discovering the benefits of a ketogenic diet for reducing inflammation, improving mental clarity, cutting fat, and even curing cancer. Famous biohacking journalist Ben Greenfield lists some of the extraordinary benefits of maintaining a ketogenic diet:

Frankly, the results of my foray into ketosis and eventually keto-adaptation were astounding. I had the best Ironman triathlon season of my life and shocking levels of mental focus and physical ease, especially for races and workouts that lasted longer than two hours. Without experiencing muscle loss, hunger pangs or brain fog, I found I could go the entire day without eating, which was enormously helpful for business and personal productivity. My gas, bloating, fermentation and GI “issues” disappeared. My blood levels of inflammatory markers like HS-CRP and cytokines dropped to rock-bottom, while my levels of good cholesterol, vitamin D, and anti-inflammatory fatty acids skyrocketed. - Ben Greenfield (2020)

Some people in ketosis lose weight

Ketogenic diets have been found effective for weight loss (Miller et al. 2020, Bueno et al. 2013), management of triglycerides (Lee & Lee 2021), treatment of Alzheimer's (Rusik et al. 2019, Henderson et al. 2009), and reduction of tumors (Weber et al. 2020).

There are also likely to be psychological benefits to ketosis. In addition to being an effective treatment for epilepsy (Operto et al 2020), the ketogenic diet reduces anxiety and can improve mental health (Norwitz et al. 2020).

Anorexia is particularly tragic, given that mortality rates among those suffering from it are higher than any other mental disorder and recovery rates are poor (Arcelus et al. 2011, van Eeden et al. 2021). However, recent case studies have revealed that a ketogenic diet has succeeded in resolving anorexia where other diets have failed (Scolnic 2017, Norwitz et al. 2023)

Like ketogenic diets, deliberate cold exposure stimulates the production of endogenous ketone bodies. Anorexics seem to have discovered this property long before it became popular among biohackers (e.g., Smith et al. 1983). One survey found that more than half of respondents with an eating disorder endorsed deliberate cold exposure in some form as a method to promote fat loss (Reas et al. 2019). Nevertheless, anorexia is a Contraindication for Cold Plunge and is ill-advised until a program suitable to the nutritional demands of the ice bath is established.

How to achieve ketosis?

Given the myriad benefits of the ketogenic diet, it makes sense that people are curious about how to increase the circulation of ketones in their bloodstream right away. Most biohackers and medical professionals will tell you that there are two ways: exogenous and endogenous.

Exogenous ketones are introduced from outside the body by eating foods or supplements that pass through the digestive tract into the bloodstream as ketones. MCT oil and ketone esters are two examples. These are especially useful for high performance, endurance athletes like Ben Greenfield, who consume enormous amounts of metabolic energy and maintain low body fat reserves.

Endogenous ketones are produced by the liver and kidneys from fat stored inside the body. The principal advantage of endogenous ketones is that they can be produced without ingesting extra foods. Moreover, the conversion process consumes some extra energy, so for people who are using a keto diet to lose weight, endogenous ketone production has the advantage of burning more fat than the exogenous approach.

The principal disadvantage of the endogenous approach is that ketone production is only stimulated after glucose reserves have been exhausted. The usual approach to transitioning from a carbohydrate (i.e., glucose) to ketone-based metabolism is to fast from carbohydrates for several days, to allow the body to use up stored glucose reserves.

That process can take several days, especially for people who are not yet keto-adapted.

Exercise will speed up the transition some. However, the amount of exercise required to deplete blood glucose and glycogen reserves is more than most people seeking to lose weight are able to endure.

Fortunately, there is a faster way.

Back in 1965, two scientists conducted an experiment in what they called "acute cold exposure" in which "four healthy young men at rest (were subjected to) a 90-min period of seminude exposure to 0 C in still air" (Hanson & Johnson 1965). During the cold exposure period, the researchers found a "significant increase in plasma free fatty acids as compared with similar control periods" and elevated levels of plasma ketones.

Just an hour and a half of freezing cold air exposure resulted in an immediate production of ketone bodies, without exercise, without fasting, and without supplements.

The decades since then have seen an explosion of new research related to cold exposure, thermogenesis, and its metabolic benefits. Critical to these research efforts was the 2009 discovery of brown fat in adults (Zingaretti et al 2009, Reinisch et al 2020). Packed with mitochondria, brown fat is critical for maintaining body temperatures in cold environments -- and acute cold exposure may be the only way of maintaining and recruiting more brown fat (da Silva et al 2019).

Ice baths are fast ketosis

What we now know is that deliberate cold exposure sets off a immediate chain reaction of metabolic responses that work faster than diet, supplements, or exercise alone to stimulate the endogenous production of ketones and accelerate the transition from carbohydrate to fat- and ketone-based metabolism.

Cold exposure clears glucose from the blood stream by increasing the effectiveness of insulin for transporting glucose into shivering muscles. It stimulates white fat cells to release stored fats into the blood stream so that that liver can produce ketones, and it supercharges the mitochondria in brown fat to produce metabolic heat in an effort to keep the body warm. In this way, cold exposure is the most effective method of inducing ketosis for people who are seeking to use a keto diet to lose fat or maintain a healthy weight.


UPDATE 27 Nov 2022

Ben Bikman, PhD (author of Why We Get Sick 2020) recently posted some brain imaging results from a talk he was about to give at a scientific conference.

According to Bikman, the brain prefers ketones over glucose. That is, you don't have to be in full ketosis for the brain to start taking up ketones for fuel from your bloodstream. As soon as your ketone levels start to rise, some brain cells will begin shifting metabolism from glucose to ketones even as the rest of the body continues to burn glucose.

These findings are consistent with a new book from Chris Palmer, MD called Brain Energy (Palmer 2022) that describes the metabolism of the brain and how he has successfully treated psychiatric patients experiencing mental disorders by prescribing a ketogenic diet.

In Prostate Protocol I wrote about how I've had success managing my own metabolism by cycling in and out of keto. So I decided to run an experiment with my ice bath and keto test strips the day after Thanksgiving. The strip on the left in the picture below marked "BEFORE" shows what happens when I eat a half a pumpkin pie after Thanksgiving dinner.

The strip on the right is a few hours AFTER I did 2 min at 34F in my ice bath.

My results are consistent with the findings in the scientific studies. Judging by the jump in ketone measured in my urine, my ice bath is the fastest way for me to get my metabolism back on track after the holiday feast.

Keto tests strips marked BEFORE and AFTER show increase in urine concentration of ketones following ice bath
My ketone levels jumped a few hours after my ice bath,


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About the Author

Thomas P Seager, PhD is an Associate Professor in the School of Sustainable Engineering at Arizona State University. Seager co-founded the Morozko Forge ice bath company and is an expert in the use of ice baths for building metabolic and psychological resilience.

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Update. I found this page from 2016 in which a biohacker named John A Buckwalter measured his ketone before and after an ice bath. Sure enough, his measured plasma ketones doubled.

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