Published May 2023 on YouTube

Dr. Susanna Søberg: How to Use Cold & Heat Exposure to Improve Your Health | Huberman Lab Podcast

1. Dr. Susanna Søberg

Dr. Susannah discusses the effects of deliberate heat and cold exposure on metabolism and neurotransmitter production, including dopamine and epinephrine. She also answers common questions about the protocols and nuances of cold and heat exposure, and emphasizes the importance of safety when practicing these methods.+

2. Sponsors: Plunge, Maui Nui, Thesis

Andrew discusses the benefits of deliberate cold exposure, especially when done up to the neck in water, with Dr. Susanna. He highlights the importance of clean water and introduces Plunge, a self-cooling cold plunge that makes it easy to get your deliberate cold exposure at home. He also talks about Maui NUI Venison, a sustainable source of nutrient-dense red meat, and Thesis, a company that designs custom nootropics to get your brain and body into specific states for mental and physical work.+

3. The Brain-Body Contract

Andrew Huberman announces two live events in Toronto and Chicago in September 2023. The events will cover mental and physical health and performance with new content not previously covered on the podcast. Use code Huberman for early access to tickets on tour.+

4. Cold Exposure Physiology

Cold Exposure Physiology:Andrew talks to Susanna about the science behind cold exposure and sauna, and how it impacts human physiology. They discuss the effects of cold plunges and sauna on the body and the benefits of deliberate cold exposure.+
Cold Water Shock:Susanna explains the physiological effects of submerging into cold water and how it activates the sympathetic nervous system. The shock from the temperature difference is less stressful if you're warm beforehand, and Andrew clarifies the role of catecholamines in the stress response.+

5. Cold Exposure Benefits

Cold Exposure Benefits:Andrew and Susanna discuss the benefits of cold exposure and how to approach it. They explain that discomfort is necessary to activate the sympathetic nervous system and build resilience. With adaptation, the initial shock of cold exposure will subside.+
Embracing Cold Discomfort:Andrew and Susanna discuss the discomfort of deliberate cold exposure and how individuals vary in their ability to embrace it. Some people feel better in the cold while others dread it, and those who avoid it may feel the pain more when they finally experience it. The discussion highlights the importance of understanding individual differences when it comes to cold exposure.+

6. Cold Exposure Benefits

Susanna explains the differences in impact between cold showers, cold immersion, and being outside in cold weather. She discusses how covering the body in cold water activates the autonomous nervous system, while being outside in cold weather activates the sympathetic nervous system and brown fat. Cold exposure activates brown fat, which increases metabolism and regulates body temperature.+

7. Brown Fat Pathways

Susanna explains that there are three parallel pathways that activate brown fat: cold receptors to the hypothalamus, cold receptors directly to brown fat, and shivering muscles to brown fat. The existence of multiple pathways shows how important brown fat is to our survival and evolution.+

8. Shivering and Brown Fat

Shivering and Brown Fat:Susanna explains how shivering is good for increasing metabolism and burning calories. The afterdrop, which causes shivering, is when the core temperature decreases even after getting out of cold water. Shivering activates brown fat which then warms up the body again.+
Cold Training Benefits:Susanna explains the benefits of cold exposure and shivering as a way to train your cells and increase insulin sensitivity. Just like exercise, the discomfort of shivering is crucial for adaptation and creating healthy stress in the body.+

9. Cold Exposure Benefits

Andrew and Susanna discuss the benefits of cold exposure, including increased activation of brown fat and improved insulin sensitivity. Cold exposure can also lead to lower blood pressure and heart rate, as well as a better stress response over time.+

10. Sponsor: AG1 (Athletic Greens)

Andrew talks about the importance of gut health and how Athletic Greens provides the optimal probiotics for microbiotic health. He also mentions how the gut communicates with the brain and immune system to impact our overall health.+

11. Blood Pressure & Heath

Andrew and Dr. Peter Atia discuss the vital importance of controlling blood pressure, as it is the number one reason for cerebral vascular and cardiovascular disease worldwide. Deliberate cold exposure is one way to control blood pressure, in addition to other forms of exercise.+

12. Brown Fat Biology

Brown Fat Biology:Susanna explains the biology of brown fat, its distribution in the body, and how it can grow with an increase in adrenaline. Brown fat is not subcutaneous fat, but rather located around the organs and can expand and decrease in size.+
Brown Fat Plasticity:Susanna and Andrew discuss the plasticity of brown fat and its association with insulin sensitivity. They also explore the link between physical activity and brown fat, with individuals who grew up doing manual labor having more brown fat.+

13. Activating Brown Fat

Activating Brown Fat:Susanna explains that brown fat can be activated with just a little bit of exposure to cold, which is the most potent stressor activator of our brown fat. You can activate your brown fat just by getting a temperature change on your skin, such as going outside in a T-shirt, wearing cooling vests, or sleeping in a cold room. Studies have also shown that brown fat activation can keep your metabolism higher and improve your insulin sensitivity.+
Brown Fat Activation:Susanna explains how exposure to cold temperatures can activate brown fat, leading to increased insulin sensitivity and decreased unhealthy white fat. She shares insights from her own study, including how even just a few minutes of cold exposure can rapidly activate brown fat and the location of brown fat in the body.+

14. Cold Resilience, Scandinavia

Brown Fat Activation:Andrew shares his experience of activating brown fat by exposing himself to cold environments, which resulted in him becoming leaner and improving his thermal regulation. He also discusses a Scandinavian saying that suggests wearing fewer layers in the fall to prepare for winter and more layers in the spring to prepare for summer.+
Scandinavian Cold Immersion:Susanna shares how Scandinavian countries have been using cold immersion to increase resilience to the cold and boost the immune system since the 1950s. This includes putting babies outside to sleep in the cold, which has been shown to activate brown fat and reduce the frequency of colds. Andrew notes how fit and healthy Scandinavians are compared to Americans, which he attributes to their cold immersion practices.+

15. Sponsor: InsideTracker

Andrew thanks Inside Tracker for sponsoring the podcast and talks about the importance of getting regular blood work done. He explains how Inside Tracker's personalized nutrition platform analyzes data from your blood and DNA to help you better understand your body and reach your health goals. The platform makes it easy to assess your levels of hormones, metabolic factors, lipids, and more, and then suggests interventions to bring those numbers into the optimal range for your health.+

16. Cold Water Benefits

Brown Fat Study:Susanna discusses her landmark study on brown fat activation through cold exposure and sauna use in human studies, highlighting the challenges of conducting research on human subjects and the importance of preventive medicine. Andrew asks for details on the study design and measurements, and Susanna shares her observations beyond the published paper.+
Winter Swimming Study:Susanna discusses the inspiration behind her study on the effects of winter swimming on brown fat activation and metabolism. Despite being a non-winter swimmer, she conducted a proof of concept study to examine the mechanisms involved and found interesting results.+
Cold Water Benefits:Susanna and Andrew discuss the benefits of cold exposure and how it can improve overall health. While Susanna was initially hesitant, she eventually tried winter swimming and found it to be invigorating. Andrew shares his own experience with deliberate cold exposure and how it has positively impacted his well-being.+
Cold Water Dips:Susanna shares her experience with cold water dips and the health benefits she observed. She emphasizes the importance of starting slow and not pushing oneself too far. Andrew and Susanna discuss the potential risks of overexposure to cold therapy.+

17. Cold Adaptation

Cold Adaptation:Susanna discusses her study on the effects of cold exposure on the body, specifically looking at winter swimmers who were already adapted to the cold. She notes that women have more brown fat than men and are physiologically colder, which may explain why they are more comfortable at higher temperatures than men.+
Thermostat Wars:Andrew and Susanna discuss the differences in thermocomfort between men and women, and how it relates to the "thermostat wars" at home. Susanna explains how they chose to study only one gender in their proof of concept study to eliminate confounding factors, and recruited winter swimmers who had been adapted to the cold but not staying in the water for too long.+

18. Cold Water Response

Susanna and Andrew discuss the physiological response to cold water immersion, including the activation of the diving reflex and parasympathetic response. They explore how this response can lead to mental balance and the need for further studies to understand its full effects.+

19. Winter Swimming Benefits

Winter Swimming Study:Susanna discusses her study on winter swimmers who take dips in cold water and sauna sessions two to three times per week. They start and end in cold water, with sauna sessions in between. The study explores the benefits of cold exposure and sauna therapy.+
Cold Water Immersion:Susanna discusses the health benefits of cold water immersion and how it can be easily accessed in nature. She emphasizes the importance of finding the right time of day for each individual to do it.+

20. Brown Fat and Cold Water

Brown Fat Activation:Susanna discusses how she measured brown fat activity through both temperature and Pet MRI scanning, which is the golden standard for measuring brown fat. She also wanted to see the circadian rhythm of brown fat activity during both experimental and normal days.+
Cold Water Adaptation:Susanna discusses her study on the effects of cold water adaptation on insulin sensitivity. Winter swimmers had lower insulin production and faster glucose clearance, despite similar perceptions of coldness compared to the control group. Andrew explains the importance of maintaining blood glucose levels for brain health and the potential neurotoxicity of high glucose levels.+

21. Cold and Heat Exposure

Susanna and Andrew discuss the health benefits of cold and heat exposure. They found that 11 minutes of cold exposure and 90 minutes of heat exposure per week can lead to reduced blood sugar, improved brown fat distribution, and reduced insulin. Overdoing it can exhaust the cells and increase the risk of cardiovascular disease.+

22. Cold Exposure Benefits

Andrew explains the benefits of cold exposure and the optimal time and frequency for cold exposure sessions. He emphasizes the importance of keeping the stimulus short and not becoming too cold adapted. The goal is to improve health metrics, not to be able to endure longer sessions.+

23. Winter Swimming Benefits

Psychological Benefits:Susanna Søberg discusses the psychological benefits of cold water swimming, including improved sleep quality and reduced social anxiety. However, she regrets not measuring sleep quality in her study.+
Naked Winter Swimming:Susanna and Andrew discuss the benefits of cold exposure and winter swimming, including the tradition of swimming naked in Denmark's oldest winter swimming club. Although skinny dipping is not legal in most places in the United States, there are nude beaches like Black's Beach in San Diego.+
Sauna and Cold Exposure:Susanna and Andrew discuss the cultural differences in sauna and cold exposure practices, including the tradition of skinny dipping in Denmark. They also highlight the growing popularity of deliberate cold exposure and sauna in mainstream medicine and the importance of wearing clothing in these practices.+

24. “Brown Fat Negative” & Shiver

Susanna and Andrew discuss observations from their study on brown fat, including a subject who did not have any brown fat and had difficulty regulating their temperature during the experiment. They also discuss the implications of these findings for understanding brown fat activation in winter swimmers.+

25. Natural Stressors

Susanna explains how exposure to natural stressors such as cold and heat can decrease inflammation in the body, which in turn can prevent lifestyle diseases and mental illnesses. She emphasizes that our modern sedentary lifestyle has made us more temperature comfortable, leading to an increase in obesity. By incorporating natural stressors like cold exposure and exercise, we can keep our bodies in a natural balance.+

26. The Soberg Principle

Susanna explains the benefits of ending on cold during cold exposure, which forces the body to heat itself back up and increase metabolism. This collaboration between brown fat and muscles keeps thermogenesis up and increases neurotransmitters, making brown fat and muscle cells more efficient. The result is a more efficient heating and cooling system.+

27. Cold Exposure: Fed or Fasted?

Andrew asks Susanna about the benefits of doing deliberate cold exposure and sauna fasted versus after a meal. Susanna mentions that she hasn't seen studies specifically on this but they did measure glucose on the cooling days, specifically on fasting and fat.+

28. Cold Exposure Benefits

Cold Exposure Benefits:Andrew and Susanna discuss the potential benefits of deliberate cold exposure for offsetting symptoms of Raynaud's Syndrome and other autoimmune conditions. While there are no studies on this specific topic, it is logical that cold exposure could increase the elasticity of small capillaries and vessels. However, more research is needed to fully understand the effects.+
Cold Exposure Tips:Susanna shares tips on how to deal with pain during cold exposure, including keeping hands and feet out of the water or wearing neoprene booties. Andrew provides reassurance that full body exposure is not necessary for a beneficial nervous system activation.+

29. Cold Immersion Tips

Cold Immersion Headaches:Andrew and Susanna discuss the origin of headaches that some people experience when doing cold immersion up to the neck. Susanna explains the decreased blood flow to the brain when submerged in cold water, while Andrew shares his personal experience and solution to eliminate the headaches.+
Cold Water Swimming:Susanna explains why it's important to keep your head out of the water while swimming in cold temperatures, as submerging your head can increase heat loss from your core by 36%. She also suggests wearing a beanie to keep the head warm and prevent dizziness. Andrew shares insights on how insulating the brain with a wool cap in a sauna can help you stay in longer.+

30. Children & Hypothermia Risk

Cold Exposure Benefits:Andrew discusses the benefits of cold exposure and how it can evoke physiological changes that are beneficial for our bodies. He also talks about the different ways people can approach deliberate cold exposure, including children, and whether it is safe for them. Additionally, he touches on male and female differences in protocols for cold exposure.+
Cold Exposure Risks:Susanna and Andrew discuss the risks of cold exposure for smaller bodied people, particularly children, who are at a greater risk of hypothermia. Andrew shares a personal experience of a 16-year-old swimmer who became hypothermic during a Pacific Ocean swim without a wetsuit. They advise caution and starting with cold showers before moving on to cold immersion.+

31. Gender Differences & Cold Exposure

Susanna and Andrew discuss the potential differences between men and women when it comes to cold exposure and brown fat activation. While women may have more brown fat, it's unclear if they need a different protocol for rapid cold exposure. However, both men and women can benefit from short, frequent exposures to increase hometic stress.+

32. Temperature Variations

Temperature Variations:Andrew and Susanna discuss the benefits of exposing your body to changing temperatures, whether it's through a sauna, cold plunge, or even just a shower. Short exposures with temperature variations can strengthen cells and create hormetic stress, which can be beneficial for the body.+
Cold Exposure Benefits:Andrew and Susanna discuss the benefits of cold exposure and how it's not just about getting cold, but going from warm to cold and from cold to warm. They emphasize the importance of keeping the system tuned by doing deliberate cold exposure at different times and changing the temperature up and down. They also mention the significance of circadian time and how our bodies go through shifts in temperature throughout the day.+
Ongoing Cold Exposure:Susanna discusses an ongoing study on cold exposure and its potential impact on health for both men and women. Andrew praises her work and highlights the lack of modern studies on the topic.+

33. Cold and Heat Exposure

Andrew discusses the science and protocols of deliberate cold and heat exposure with Dr. Susannah, including the benefits and risks of each. They also recommend Dr. Susannah's book Winter Swimming and Momentous Supplements for those interested in learning more.+