What Is the Søberg Principle?

By Dr. Susanna Søberg, PhD · Søberg Institute · soeberginstitute.com

If you have spent any time in the world of cold water immersion, contrast therapy, or metabolic health, you have likely encountered the term the Søberg Principle. But what does it actually mean? Where does it come from? And why does it matter for your health?

This article explains the Søberg Principle in full — its scientific origin, its meaning, and why it has become one of the most referenced findings in the global thermal health movement.

The Origin — Published Science, Not a Wellness Trend

The Søberg Principle is not a brand name, a marketing slogan, or a social media trend. It is a specific finding that emerged from peer-reviewed scientific research published in Cell Reports Medicine in October 2021.

The study was conducted by Dr. Susanna Søberg, PhD, a Danish scientist specialising in metabolism and human physiology at the University of Copenhagen. Dr. Søberg spent over a decade studying how deliberate cold and heat exposure affect the human body at a metabolic and physiological level.

The 2021 publication — titled "Habitual cold exposure and brown adipose tissue" — examined how regular, structured contrast therapy influences brown adipose tissue (brown fat) activation and metabolic outcomes in humans.

It was one of the first peer-reviewed studies to examine the specific protocol variables — not just whether cold exposure works, but exactly how it should be structured to produce measurable metabolic results.

What the Søberg Principle States

The Søberg Principle refers to the finding that ending a contrast therapy session with cold — rather than heat — produces a stronger and more sustained activation of brown adipose tissue and a more significant metabolic response.

In simple terms: when you alternate between cold and heat exposure, the order in which you finish matters for the physiological outcome.

This finding was reproducible, measurable, and specific — the hallmarks of a genuine scientific principle rather than a general recommendation.

The principle has since been adopted and referenced across the global wellness industry, cited in health media, discussed on major podcasts including Huberman Lab and The Joe Rogan Experience, and applied in wellness settings across more than 25 countries.

Why Brown Fat Matters

To understand why the Søberg Principle matters, it helps to understand what brown adipose tissue (brown fat) actually is.

Unlike white fat — which stores energy — brown fat is metabolically active. It burns calories to generate heat. It contains a high density of mitochondria, which gives it its characteristic brown colour and its remarkable ability to produce energy.

For decades, scientists believed that humans lost most of their brown fat after infancy. Dr. Søberg's research was part of a growing body of evidence confirming that adult humans retain meaningful deposits of active brown fat — and that deliberate cold exposure is one of the most effective ways to activate it.

Activated brown fat contributes to:

•        Increased caloric expenditure

•        Improved insulin sensitivity

•        Better thermoregulation

•        Metabolic flexibility — the ability to switch between fuel sources efficiently

The Søberg Principle is specifically about how to maximise this brown fat activation through structured contrast therapy — not just whether cold exposure is beneficial, but precisely how to use it.

The Research Behind the Principle

Dr. Søberg's 2021 study in Cell Reports Medicine was the culmination of years of research into human metabolism and thermal physiology. It examined participants who engaged in regular contrast therapy — alternating between cold water immersion and heat exposure — and measured the physiological outcomes based on different protocol structures.

The publication in Cell Reports Medicine — a highly respected peer-reviewed journal from Cell Press, the same publisher as the journal Cell — represented a significant contribution to the scientific literature on metabolic health and thermal stress.

The research confirmed that the body's metabolic response to contrast therapy is not simply a function of exposure time or temperature — it is significantly influenced by the structure and sequence of the protocol.

Global Recognition and Adoption

Following publication, the Søberg Principle gained rapid recognition across the global health and wellness community.

Dr. Søberg appeared on Huberman Lab — consistently ranked as one of the top science and health podcasts globally — where the principle was discussed in depth with Andrew Huberman of Stanford University. The episode reached millions of listeners worldwide.

The research was subsequently discussed by Andrew Huberman and Joe Rogan on The Joe Rogan Experience, Episode 1842 — one of the most listened-to podcast episodes in the world — bringing the Søberg Principle to an audience of tens of millions.

The principle has since been featured in The New York Times, The Times, The Guardian, and BBC Radio, and has been applied in wellness settings — from luxury spas and premium fitness facilities to clinical and hospitality environments — across more than 25 countries.

Dr. Søberg has trained and certified over 250 instructors worldwide in the application of the Søberg Principle and the Thermalist® Method, the structured contrast therapy operating system built on this research.

The Søberg Principle and the Thermalist® Method

The Søberg Principle is the scientific foundation upon which the Thermalist® Method is built. The Thermalist® Method is Dr. Søberg's structured contrast therapy system — a complete operating system for cold and heat exposure that translates the peer-reviewed science into a practical, teachable, and measurable protocol for both individuals and wellness operators.

The Thermalist® Method is now available for licensing to premium wellness facilities, spa hotels, and hospitality operators through the Thermalist® Recovery System at thermalist.com.

For individuals who want to learn the science and apply it in their own lives, Dr. Søberg offers four online courses at the Søberg Institute — including the Thermalist® Method at Home course, the Cold Water Immersion Course, the 3 Week Thermalist Cure®, and the Søberg® 12-Week Reset.

Who Is Dr. Susanna Søberg?

Dr. Susanna Søberg is a Danish scientist with a PhD in metabolism from the University of Copenhagen. She has spent over 15 years researching the physiological effects of cold and heat exposure on the human body — with a particular focus on brown adipose tissue, metabolic health, stress physiology, and nervous system regulation.

She is the author of the international bestseller Winter Swimming, the founder of the Søberg Institute, and the founder of Thermalist® — the world's leading contrast therapy method and recovery system.

Her research has been cited in major international media, discussed on the world's largest health and science podcasts, and applied by practitioners and wellness operators in more than 25 countries.

She is available for keynote speaking, scientific advisory roles, and selected brand partnerships through the Søberg Institute.

Summary — What Is the Søberg Principle?

The Søberg Principle is a specific, peer-reviewed scientific finding published in Cell Reports Medicine in 2021 by Dr. Susanna Søberg, PhD. It states that ending contrast therapy with cold — rather than heat — produces the strongest metabolic response, including the most significant activation of brown adipose tissue.

It is not a trend, a brand name, or a general wellness recommendation. It is a measurable, reproducible finding from one of the world's most respected scientific journals — and it is now the foundation of a global movement in thermal health practiced across more than 25 countries.

To learn more about the Søberg Principle and how to apply it in your own life, explore Dr. Søberg's online courses at soeberginstitute.com. To bring the Thermalist® Method to your wellness facility, visit thermalist.com.