The Proof with Simon Hill
Science of ice baths, brown fat and metabolism | Susanna Soeberg, PhD
Episode guests
Podcast summary created with Snipd AI
Quick takeaways
- Brown fat activation through cold exposure increases thermogenesis and boosts metabolism.
- Exposure to cold water leads to acute physiological responses and activation of the sympathetic and parasympathetic nervous systems.
- There is currently no definitive test for measuring the amount of brown fat in an individual, but regular exposure to cold and heat can influence its growth and efficiency.
- Long-term studies on the health benefits of cold water immersion are limited, but sauna cohort studies suggest cardiovascular health benefits.
- To make cold exposure a regular practice, choose a suitable time of day, start slowly, and gradually increase duration and intensity.
Deep dives
Brown fat activation and its role in metabolism and health
Brown fat is a thermogenic tissue in our body that generates heat by using glucose and fat. Activation of brown fat increases thermogenesis and boosts metabolism, leading to better glucose regulation and insulin sensitivity. Regular exposure to cold temperatures can increase brown fat efficiency and make the body more effective at generating heat. Brown fat activation also leads to lower inflammation in the body, which is associated with improved cardiovascular health and reduced risk of lifestyle diseases such as obesity and type 2 diabetes.
Physiological responses to cold water immersion
When exposed to cold water, the body has acute responses such as increased heart rate, blood pressure, and respiratory rate. The sympathetic and parasympathetic nervous systems are activated, releasing hormones like noradrenaline and dopamine. Activation of brown fat occurs, which uses glucose and fat to generate heat, increasing metabolism and clearing glucose from the bloodstream. Over time, adaptation to cold exposure leads to more efficient brown fat activation, improved vascular responsiveness, and increased heat generation.
Determining brown fat levels and its growth potential
There is currently no definitive test to quantify the amount of brown fat in an individual. PET/CT scans can measure brown fat activity, but they are costly. Indirect measurements like cold tolerance and ability to generate heat can provide some indication of brown fat presence. While genetics may play a role, environmental factors like regular exposure to cold and heat can influence brown fat growth and efficiency.
Long-term health benefits and potential risks of cold exposure
Long-term studies on the health benefits of cold water immersion, such as lower incidence of type 2 diabetes and reduced risk of obesity, are limited. However, the sauna cohort studies indicate a dose-response relationship between sauna use and cardiovascular health benefits. Regular exposure to cold and heat stressors can improve glucose regulation, lower inflammation, and contribute to overall health. It's important to find the right balance, as overexposure to extreme cold or prolonged exposure to cold might have diminishing health benefits or potential risks.
Getting Started with Cold Exposure
For someone new to cold exposure, it's important to prepare yourself mentally and understand the benefits. Start by familiarizing yourself with the idea of cold water immersion and its potential health benefits. To begin, choose a suitable time of day, preferably in the morning or afternoon, when your core temperature is warmer. If you're fearful, it's normal. Focus on controlling your breathing as you enter the cold water, breathing in through the nose and exhaling slowly. You can choose to gradually enter the water, going halfway in or taking a quick plunge and then getting out. Find what works best for you and go at your own pace.
The Physiological Response to Cold Exposure
When you expose yourself to cold water, your body experiences a range of physiological responses. Within minutes, there is a significant increase in neurotransmitters like dopamine, norepinephrine, and serotonin, which can improve mood and mental focus. This response can help regulate your immune system and decrease inflammation. Cold exposure has also been associated with increased activation of brown fat, which can lead to a boost in metabolism. Regular cold exposure may have positive effects on mental health, including reducing anxiety and depression symptoms.
Choosing the Right Time and Frequency
To make cold exposure a regular practice, consider finding a time that best fits your routine and preferences. Some people prefer starting their day with cold exposure, while others find it beneficial in the afternoon. Avoid cold exposure right before bedtime, as it can activate your sympathetic nervous system and make it harder to sleep. When it comes to frequency, start with what feels comfortable for you. Whether it's a few times a week or daily, consistency is key. Gradually increase the duration and intensity of your cold exposure as your body adapts over time.
Tailoring Cold Exposure to Your Needs
Cold exposure can be customized to meet your specific goals and preferences. If you prefer to ease into it, begin with shorter durations or midway immersion. Focus on nasal breathing and try to lower your breathing rate to calm your nervous system. If you're looking for an intense experience, opt for full-body immersion for a few seconds. Remember, everyone's tolerance and adaptation to cold exposure vary, so listen to your body and find what works best for you. Experiment with different techniques and durations to find your sweet spot.
Importance of Listening to Your Body and Not Overdoing It
When engaging in cold water exposure, it is crucial to listen to your body and avoid overdoing it. It is rare for first-timers to stay long enough in the water to reach a state of calmness, especially if they have sedentary indoor jobs. The cold adaptation of individuals who work outside, like builders, differs from those sitting in a temperature-controlled environment. Everyone's ability to withstand the cold varies due to factors such as muscle mass and blood circulation. The key is to focus on how your body feels during cold water exposure and to remember that it is not a competition but a self-care practice to connect with nature and improve metabolism.
The Optimal Duration and Safety of Cold Water Exposure
Research suggests that a safe and effective weekly goal for cold water exposure is around 11 minutes divided into two to three sessions, each lasting one to two minutes. While even shorter durations can provide metabolic benefits, 11 minutes per week is a tested and recommended duration. It is essential to avoid overexposure or setting arbitrary targets, as prolonged cold water exposure may lead to chronic stress and potential long-term negative effects. It is advisable to start with shorter durations and progressively increase the time spent in cold water. Additionally, it is important not to underestimate the potential risks and to prioritize safety when engaging in cold water immersion.
Episode #250. Ice baths and other forms of cold water exposure have gained a huge amount of traction in the past few years. I’m joined by expert Dr Susanna Søberg to examine what the science says – is cold water exposure safe? What does the research say about the bold health claims? Is brown fat just a buzzword? How do you safely and effectively implement hot and cold exposure into your life? Dr Søberg answers these questions and many more in this three-hour deep dive into cold water immersion.
Specifically, we discuss:
- Intro (00:00)
- The tradition of winter swimming (01:52)
- Cold water swimming and activating brown fat (09:44)
- Dr. Søburg's personal experience with cold water bathing (23:13)
- Funding hurdles and potential benefits of cold water immersion (25:34)
- Cold water immersion and the body's response (33:36)
- Brown fat activation and more physiological responses (40:45)
- What is brown fat? (45:54)
- Is brown fat genetic? (55:28)
- Benefits of activating brown fat (58:32)
- Winter swimming, sauna, and disease: what the data says (1:01:10)
- Metabolism and shivering (1:13:01)
- Brown fat activation and muscle building (1:25:06)
- Who has more brown fat: Women or Men? (1:36:33)
- Chronic inflammation, exercise, and more benefits of deliberate cold exposure (1:46:11)
- Cold water immersion for beginners (2:06:18)
- The minimum threshold for health benefits using cold and heat (2:15:03)
- Clothes or no clothes? (2:22:57)
- Temperature regulation and gender differences (2:26:30)
- Safety protocols & understanding ice plunging lingo (2:34:08)
- Outro (2:47:18)
To connect with Dr Susanna Søberg, you can find her on Instagram, Twitter, Facebook, TikTok, and LinkedIn. Head to her website, www.soeberginstitute.com, to learn more about Dr Søberg’s work – including her research and her book Winter Swimming. Friends of The Proof can also receive a 10% discount on her Thermalist course with code SIMONHILL.
Discover more insights and supporting resources in the full show notes.
Enjoy, friends.
Simon
Want to support the show?
The best way to support the show is to use the products and services offered by our sponsors. To check them out, and enjoy great savings, visit theproof.com/friends. You can also show your support by leaving a review on the Apple Podcast app and/or sharing your favourite episodes with your friends and family.
Simon Hill, MSc, BSc (Hons)
Creator of theproof.com and host of The Proof with Simon Hill
Author of The Proof is in the Plants
Watch the episodes on YouTube or listen on Apple/Spotify
Connect with me on Instagram, Twitter, and Facebook
Nourish your gut with my Plant-Based Ferments Guide
Download my complimentary two-week meal plan and high protein Plant Performance recipe book
Remember Everything You Learn from Podcasts
