Cutting through the bs on cold exposure (embrace the winter)

The external environment plays a crucial role in our health, often overlooked in favor of dietary choices and exercise regimens. While many focus on consuming healthy foods and maintaining an active lifestyle (these are obviously important) , the influence of environmental factors—particularly temperature—on our physiological adaptability is significant and often overlooked. Sun exposure is one environmental factor that’s particularly important for immune health and stabilizing the circadian rhythm. But you may be suprisd to find that seasonal tempature variations are another environmental cue that also impacts these systems.

Temperature serves as a critical environmental cue that affects various biological processes in mammals. For instance, exposure to cold can stimulate the hypothalamus to release thyroid hormones, increasing metabolic rates and promoting heat production through thermogenesis in brown adipose tissue. This physiological response is essential for maintaining homeostasis in fluctuating temperatures, particularly during winter months. While the actual extent to which cold improves things like ‘fat burning’ (in absence of things like caloric restriction) is heavily debated in the fitness community, the mechanisms underpinning the phenomenon are real and have been empirically verified time and time again.

Historical context of intentional cold exposure

Historically, many cultures around the world have recognized the health benefits of cold exposure. In Russia, the practice of cold inoculation involved exposing infants to cold temperatures, often by placing them outdoors in winter. This practice was rooted in the belief that those exposures could strengthen the immune system and promote overall health. The rationale was that acclimatizing children to cold environments would enhance their physiological resilience, preparing them for the harsh winters and reducing susceptibility to illnesses.

In Nordic countries, outdoor napping for babies is a common practice, even in sub-zero temperatures. Research indicates that children who sleep outdoors tend to have longer and more restful naps compared to those who sleep indoors. This practice is based on the belief that fresh air and cold exposure can reduce the incidence of respiratory infections and improve overall well-being. The Swedish saying, "There is no bad weather, only bad clothing," encapsulates this philosophy.

In contemporary discussions, cold exposure therapy (like ice baths and cold showers) has gained popularity for its purported health benefits, including improved cardiovascular function and increased metabolic rates through brown adipose tissue activation. While studies do suggest that regular cold exposure can lead to favorable changes in blood factors and a reduction in cardiovascular disease risk, I wouldn’t get too caught up in published research. Instead of doing cold exposure because [insert study showed], it’s likely a better idea to simply engage in natural forms of cold inoculation (like exposing yourself to the elements) as these were simply a natural, normal part of our ancestors daily lives.

A lot of health influencers hyper-fixate on the idea that we need to experimentally ‘prove beyond a shadow of a doubt’ that cold exposure is beneficial for [insert health benefit] before engaging in the practice. This is rather silly. Remember, we aren’t talking about experimental drugs here. We’re discussing the benefits ‘adding back’ something that used to be a normal part of life.

Instead of justifying why we should be doing some form of intentional cold exposure, we should instead be asking why we stopped doing it in the first place. The precautionary principle, aka Chestertons fence, is a great heuristic to abide by. quote — ‘Chesterton urged us to respect fences and traditions, even - or perhaps especially - when we don't grasp their purpose’. His maxim goes: “Don't ever take a fence down until you know the reason it was put up”

Despite the benefits, it is essential to approach cold exposure with some caution, particularly for vulnerable populations. If you have a health condition (particularly autoimmune, high cortisol, or cardiovascular complications) intentional cold might not be the best fit for you right now. As always, approach this with common sense. Your health is your responsibility.

Thermoplastic biology in mammals (the nerdy science)

So how does cold impact our biology? Well, many organisms (especially humans) utilize temperature as a critical environmental cue to regulate their biological processes through a variety of mechanisms, particularly in thermoregulation, metabolism, and gene expression, and circadian alterations (if you want a deep dive into the circadian biology, I would highly suggest reading my ‘the under appreciated benefits of cold’ article linked bellow)

https://www.patreon.com/posts/106693972?utm_campaign=postshare_creator

In mammals, temperature influences physiological functions via a complex interplay of thermoreceptors, neuroendocrine responses, and metabolic pathways. Thermoreceptors located in the skin and hypothalamus detect changes in ambient temperature, which trigger responses that maintain homeostasis. For instance, in cold environments, the hypothalamus will stimulate the release of thyroid hormones as we mentioned briefly above, which enhance metabolic rates, promoting heat production via thermogenesis in brown adipose tissue.

Concurrently, various signaling pathways, such as those involving AMP-activated protein kinase, are readily activated to enhance energy expenditure and fat oxidation. As seasons change, particularly leading into winter, organisms undergo a series of genetic and epigenetic adaptations; for example, the expression of cold shock proteins and heat shock proteins is upregulated, facilitating cellular protection and stress responses. Cold exposure has been shown to induce mitochondrial biogenesis as well.

Cold shock proteins and heat shock proteins are critical for cellular stress responses. CSPs are produced in response to cold temperatures and help stabilize RNA and proteins, preventing damage during cold stress. They also help our cells adapt to other stressors. HSPs, on the other hand, are produced in response to heat stress and assist in protein folding and protection from aggregation. Both types of proteins play a role in maintaining cellular integrity and function under extreme stress, which ensures that cells can adapt to temperature changes themselves but also other stressors!

Mitochondrial biogenesis refers to the process by which cells increase their mitochondrial mass and function. This process is particularly relevant during periods of cold exposure, as it enhances the cell's ability to produce ATP, our primary energy currency of the cell. Cold exposure stimulates various signaling pathways that lead to the activation of transcription factors responsible for mitochondrial biogenesis, such as PGC-1α.

More mitochondria = more energy production, enhanced metabolic flexibility and possibly better health overall.

Seasonal tempature changes also cause well defined alternations in gene expression ( temperature-sensitive transcription factors) patterns associated with metabolism, circadian rhythms, and immune responses.

(Anyone telling you that tempature isn’t a useful lever you can pull for health related benefits is clueless. Full stop. I hope that’s become abundantly clear so far!)

thermobiological adaptions impact DNA methylation and histone acetylation and determines how organisms adapt to various stressors. That used to be really important (before we lived in air conditioned bubbles) because it allowed for a flexible response to environmental stress. That innate plasticity is part of surival. It’s what enabled organisms to optimize their physiological functions in response to the seasonal variations in temperature, thereby increasing other relevant aspects related to their fitness, reproduction, and survival strategies within their respective ecological niches. Tempature (just like light) is another environmental cue. It’s part of the reason why you need to be out and about in the winter and summer months.

So how do you practically go about doing this?

If you live at a high latitude at negative tempatures, going shirtless is the winter might not be practical (or safe), especially you haven’t build up any tolerance. What I recommend instead is doing graded exposure in the months leading up to the winter. 20-30 degrees farrenhite is usually the lowest most people are willing to comfortably go in shirts with no shirt. But you can experiment with what’s tolerable for you. I don’t expect anyone to go out in negative tempatures without any clothing on, nor would I personally do this myself.

If you’re used to bundling up immediately as soon as the tempature begins to drop in the fall, this may seem daunting. Its really not if you start slow. if you embrace the tempature change as early as possible before layering up (usually around 45-50 degrees), transitioning to the freezing tempatures and possibly bellow will feel like a breeze (no pun intended).

You can think of this almost like strength training, where you gradually acclimate to increased training loads over time. Just like you wouldn’t jump from a 135lbs squat to loading up 315 on the bar, you shouldn’t jump straight into extreme tempatures either.

Its important to exposure yourself to the early temperature changes as soon as possible so you 1. Have time to adapt 2. Can capture some of the more tolerable tempatures before they drop off considerably. If you live at a lower latitude (like I do here in Texas) the entire winter is probably going to be fair game since it never really gets that cold. This doesn’t mean you need to be a psychopath and embrace the cold at all times. Simply have a dedicated period of time (I usually like catching the sun in the morning for 1-2 hours shirtless) where you intentionally aim to embrace the cold. If it’s more convient, you can also try micro-dosing your exposure (5-30min intervals) throughout the day.

Building up slowly (especially with the colder tempatures) can also be helpful. Try 5min initially, and gradually increase as deemed tolerable. You can also use cold showers for this, starting with tolerable but slightly uncomfortable tempatures and gradually increasing to 2-3min at a time with colder settings. Ice baths can also be effective but I’ve found they’re a little unnecessary, especially in the winter. If you do decide to use them, avoid going lower than 45-50 degrees. This is sufficent for receiving the benefits of cold therapy. Remember, it’s better to go longer at higher tempatures, than shorter exposures at colder temperatures.

If this is still too much right out of the gate, you can try sitting outside with a reptile infared heat bulb (this is great because it will also help supplemental some needed infared light during the winter when there’s less sun. Really any brand will do) or soaking the hands and feet in warm water while you expose the rest of the body to the cold. You can gradually remove these as you begin to adapt. If you can sit in the sun (or near a red light panel) while doing your ‘cold inoculation’) this is even better. Cold decreases the surface area of the skin, and allows light photons to pass through the skin easier.

Remember, this will be a lot easier if you gradually acclimate in the months leading up to the bigger tempature drops. One of the advantages to this is that you won’t get cold when you’re fully clothed. Embracing the winter will help you adapt so it’s more palatable. This is no different than how we might approach fitness for improved quality of life and ease of motion during our day-to-day activities.

Get cold!