The Proof Gap
What cold and heat science can prove today, and what it cannot
Dr. Susanna Søberg, PhD · soeberginstitute.com
If you have followed my work for any length of time, you know I try to tell you both halves of the truth at once.
Here is the first half. Cold and heat are two of the oldest practices in human history, and we now have real science explaining why they work.
Here is the second half. A large amount of what you see online about them is not proven. Some of it is early. Some of it is extrapolated from a single study. Some of it is simply wrong.
Both halves are true at the same time. That is uncomfortable for the internet, which prefers one clean claim per video. It is not uncomfortable for a scientist. It is the normal state of a young field.
So I am starting a series.
Over the next weeks I am going to take the biggest claims in cold, heat, and contrast therapy and sort them into three honest piles. What the evidence supports well. What is promising but not yet settled. And what is being sold to you with far more confidence than the data allows.
I have spent my research career studying how the human body responds to cold and heat, including the ways men and women respond differently, and I published the protocol that much of this conversation now references. I am not here to defend cold and heat. I am here to show you where the line between evidence and hope actually sits, because you deserve to know which side of it you are standing on.
The three piles
Proven. The cardiovascular adaptations to regular heat exposure are well documented. The cellular stress response, including heat shock proteins, is real and measurable. The acute metabolic and nervous system effects of cold are real. These are not in serious scientific dispute, and they are the reason I built my life’s work around this.
Promising but unsettled. Long lasting mental health benefits. Effects on specific hormones. Some of the immunity claims. Many of these have a plausible biological mechanism and some early human data, but not the weight of evidence that would let me promise you an outcome. When a claim sits in this pile, I will tell you, and I will tell you why.
Oversold. Precise numbers attached to vague benefits. Single studies presented as settled fact. Protocols that take a result from one group of people and apply it to everyone, regardless of sex, age, or training history. This is where most of the weekly claims live.
Why this matters to you, not just to scientists
When everything is presented with the same confidence, you cannot tell the difference between a practice worth building into your life and a trend worth ignoring.
So you do one of two things. You believe too much, and you are disappointed when the miracle does not arrive. Or you dismiss the whole field, because some of it was exaggerated and you assume all of it was.
Both are a loss. The proven part is genuinely good for you. It would be a shame to lose it inside the noise.
What is coming
Cold. What it really does to your metabolism, and where the brown fat story is solid versus where it has been stretched.
Heat and the heart. The strongest evidence in the entire field, and why it matters more for women after midlife than almost anyone is saying.
Contrast. Why combining cold and heat is not simply cold plus heat, and what the science says about completing the cycle.
And finally, the honest unknowns. The questions I cannot answer yet, and the ones I am working on right now.
Some of these pieces will be open to everyone, because the core science should be. A few will go deeper into the actual protocols, the dose, the timing, and the precision I usually reserve for the people who support this work directly. I will always be clear about which is which.
One ask
If you want the whole series, the simplest thing you can do is subscribe. It is free, and it is the only way to be sure the next piece reaches you.
And if there is a claim you keep seeing and want me to put under the light, leave it in the comments. I am building part of this series around the questions you bring me.
Both halves of the truth. Every time.
Dr. Susanna Søberg
great initiative, looking forward to read it, hope you will talk about ice swimming's effects too, if there are any proven results yet. thank you
I hear other sauna users talk about the exact same protocols for sauna and cold exposure yet there seem to be so many variables between these people, gender, age, frequency of use per week, current health level, health outcome goals, etc.
So it seems unnatural to me that there can be a ‘one size fits all’ protocol for hot and cold exposure that produces the same desired results.
How do you determine what the correct protocol is for yourself, short of saying listen to your body.