Understanding Your Body in the Cold: A Deeper Look at Sex, Hormones and Adaptation

Why Does Cold Water Affect Everyone Differently?

Cold water immersion has become one of the fastest-growing trends in health and wellbeing, with more people embracing cold plunges and contrast therapy as part of their recovery and wellness routines. Whether it's an ice bath after exercise or a sauna followed by a cold plunge, the practice is increasingly recognised for its physical and mental benefits.

Yet spend a few minutes around any cold plunge, and one thing quickly becomes clear: not everyone experiences the cold in the same way. Some people settle into the water within seconds, while others are still catching their breath. Some adapt quickly, while others find every session a challenge. If everyone is immersed in the same cold water, why does the experience feel so different?

The answer lies in our physiology. Research shows that body composition, hormones, metabolism, previous cold exposure and biological sex all influence how we respond to cold water immersion. These factors affect everything from the intensity of the initial cold shock response to how efficiently the body adapts over time. One of the most interesting findings is that many of the differences commonly associated with men and women become much smaller once body composition is taken into account.⁴

Understanding these differences helps explain why there isn't a one-size-fits-all approach to cold therapy. In the sections that follow, we'll explore how sex, hormones and body composition influence the body's response to cold, what current research tells us about cold adaptation, and why recognising these differences can help you better understand your own experience in the water.

Men, Women and the Physiology of Cold

Why do men and women often experience cold differently?

Men and women can experience cold water immersion differently, but those differences are about far more than biological sex alone. Body composition, hormones and metabolism all influence how quickly heat is lost, how efficiently it's produced and how intensely the cold is perceived.¹

On average, men tend to have more lean muscle mass, which helps generate heat during movement and shivering. Women generally have a higher percentage of body fat, which can provide insulation and slow heat loss under some conditions. Despite this, many women report feeling colder than men.

That doesn't necessarily mean women tolerate the cold less effectively. Hormonal influences, changes in blood flow and greater cooling of the hands, feet and skin can make cold feel more intense, even when the body is protecting its core temperature just as effectively.¹

Perhaps the most surprising finding from cold physiology research is that many apparent differences between men and women become much smaller once researchers account for body composition.⁴

In practice, this means two women may respond more differently to the same cold plunge than a woman and a man with very similar physiques. 

How Hormones Influence Cold Water Immersion

Hormones play a central role in temperature regulation, influencing blood flow, metabolism and the body's internal thermostat. For women, natural hormonal fluctuations throughout the menstrual cycle can make the same cold plunge feel different from one week to the next.¹

Oestrogen and progesterone

Oestrogen helps regulate blood vessel function and acts on areas of the brain involved in temperature regulation.¹ Progesterone has a different effect. During the second half of the menstrual cycle, rising progesterone increases resting core body temperature by around 0.3–0.5°C and shifts the body's thermal set point, influencing when heat-conserving responses such as vasoconstriction begin.¹

These natural hormonal changes help explain why some women feel more comfortable during certain phases of their cycle than others. Some notice clear differences, while others experience very little change at all.

Testosterone

Testosterone also influences how the body responds to cold, although mostly indirectly. Higher testosterone levels are associated with greater lean muscle mass, which contributes to heat production during movement and shivering.³

Rather than making someone naturally better at cold plunging, testosterone shapes some of the physical characteristics that influence how the body generates heat.

Why your cold plunge may feel different throughout the month

If you've ever wondered why one cold plunge feels surprisingly manageable while another feels unusually challenging, your menstrual cycle may be part of the answer.

As oestrogen and progesterone rise and fall, body temperature, circulation and thermal perception can shift too.¹ Paying attention to these patterns can help you work with your body instead of feeling frustrated when the same water feels completely different from one week to the next.

Brown Fat: Your Body's Internal Heating System

While hormones help shape your immediate response to cold, your body can also adapt over time. One of the most fascinating adaptations involves brown adipose tissue, more commonly known as brown fat.

Unlike white fat, which stores energy, brown fat is specialised to produce heat.³ When activated by cold, it consumes energy to help maintain body temperature without relying solely on shivering—a process known as non-shivering thermogenesis.

Research suggests that regular cold exposure may increase brown fat activity, making heat production more efficient over time, although the degree of adaptation varies between individuals.¹ Brown fat also takes up glucose and lipids from the bloodstream while active, and researchers continue to investigate how this may contribute to broader metabolic health.

Finding Your Own Cold Plunge Routine

One of the biggest misconceptions about cold water immersion is that there's a universal formula. Three minutes. Five degrees. Stay longer. Push harder.

Your ideal cold plunge depends on your body, your experience and how you're adapting over time. Hormones, body composition, metabolism and previous cold exposure all play a role, which means the best routine is one you can approach consistently, safely and with confidence.

If you're new to cold plunging, start with shorter immersions and allow your body time to adapt. Many people find that, with regular practice, their breathing settles more quickly and the initial shock becomes less overwhelming. The cold doesn't necessarily become warm; it simply becomes more familiar.

At The Hot Box Co., we believe the most rewarding cold plunge isn't measured by the time on a stopwatch. It's measured by understanding your body, respecting its signals and building a practice that's both safe and sustainable.

Frequently Asked Questions

Why do women often feel colder than men?

Women often report feeling colder because hormones, blood flow and thermoregulation influence how cold is perceived. This doesn't necessarily mean they tolerate cold less effectively, as body composition and individual physiology also play important roles.¹

Does body fat help you stay warmer in cold water?

Body fat can slow heat loss by providing insulation, but cold tolerance also depends on lean muscle mass, body size, metabolism and previous cold exposure.^1,4

Can cold plunging increase brown fat?

Research suggests that repeated cold exposure may increase brown fat activity, helping the body generate heat through non-shivering thermogenesis. However, scientists are still investigating how these adaptations occur, and individual responses vary.³

Does the menstrual cycle affect cold plunging?

Yes. Changes in oestrogen and progesterone influence body temperature and thermoregulation, meaning some women find cold water immersion feels different throughout their menstrual cycle.¹

How long should beginners stay in a cold plunge?

There's no universal time that suits everyone. Beginners should start with short immersions, build confidence gradually and focus on how their own body responds rather than aiming for a specific duration.

Is everyone able to adapt to cold water?

Many people develop physiological adaptations with repeated cold exposure, but the extent of those changes varies. Factors including age, hormones, body composition and previous cold exposure all influence how the body adapts over time. ^3,2

References 

1. Greenfield, A.M., Charkoudian, N. and Alba, B.K. (2022) ‘Influences of ovarian hormones on physiological responses to cold in women’, Temperature, 9(1), pp. 23–45. https://doi.org/10.1080/23328940.2021.1953688

2. Kong, Y. et al. (2024) ‘Sex differences in autonomic functions and cognitive performance during cold-air exposure and cold-water partial immersion’, Frontiers in Physiology, 15, 1463784. https://doi.org/10.3389/fphys.2024.1463784

3. Mengel, L.A. et al. (2020) ‘Gender Differences in the Response to Short-term Cold Exposure in Young Adults’, The Journal of Clinical Endocrinology & Metabolism, 105(5), pp. e1938–e1948. https://doi.org/10.1210/clinem/dgaa110

4. Tikuisis, P. et al. (2000) ‘Comparison of thermoregulatory responses between men and women immersed in cold water’, Journal of Applied Physiology, 89(4), pp. 1403–1411. https://doi.org/10.1152/jappl.2000.89.4.1403