Can Sauna and Cold Exposure Support Weight Management?

Contrast therapy as a physiological stress cycle

It’s important to be clear from the outset that contrast therapy is not a ‘fat loss shortcut’. Instead, the research suggests it may act as a supportive tool that helps the body function more efficiently, particularly through effects on circulation, stress regulation, inflammation and metabolic efficiency. But really, what really does this all mean?

As is widely known, alternating between extreme heat and cold creates a controlled stress-response cycle in the body. Both heat and cold are forms of hormetic stress, which are mild stressors that stimulate adaptive biological responses. Meaning your body is forced to adapt to the uncomfortable conditions of both the intense heat and the chilling cold.

According to research on sauna bathing, both traditional and infrared saunas trigger cardiovascular, endocrine and metabolic responses that mimic light-to-moderate exercise in some respects, including increased heart rate and circulation changes. Some call this a ‘passive cardiovascular workout’. At Rejoov, we have received anecdotal feedback from clients which supports this notion, often with immediate results which can be shown on health-tracking watches.

Some call contrast therapy a passive cardio workout

A study published in the Complementary Therapies in Medicine Journal in 2019 concluded that ‘Contrary to popular belief, acute sauna use does not lead to a reduction, but to an increase in blood pressure and heart rate with a consequent increase in myocardial oxygen consumption. The cardiac load during the sauna use corresponds to a moderate physical load of 60-100W’. The study participants enjoyed a 25-minute sauna session.

Other studies consistently show that regular sauna bathing is associated with a range of cardio-metabolic benefits, including improvements in vascular function.

Cold exposure, on the other hand, activates thermogenesis which is the body’s heat-producing mechanism, which requires energy expenditure and increases sympathetic nervous system activity (another form of stress). 

The idea that cold exposure can increase metabolism is not new. In fact, scientists have been studying cold-induced thermogenesis (CIT) since as early as 1780, when French Chemist Antoine Lavoisier first explored how the body produces heat.

When exposed to cold, the body works to maintain a stable core temperature by increasing energy expenditure and activating heat-producing processes. More recently, research has focused on brown adipose tissue (brown fat), a specialised type of fat that becomes active in cold conditions and helps generate heat by burning calories.

Studies over the past two centuries have shown that cold-induced thermogenesis can vary widely between individuals depending on factors such as age, body composition, duration of cold exposure and the temperature itself. Researchers continue to explore how these thermogenic responses support overall health outcomes.

While research is still evolving, cold exposure is widely recognised for its role in non-exercise activity thermogenesis (NEAT), the energy the body uses outside of intentional (or traditional) exercise.

The key point is not that cold plunging burns fat directly, but that it may increase energy turnover and metabolic responsiveness, especially when used consistently as part of a broader lifestyle. And this can play an important part in maintaining a healthy weight.

When combined, these alternating stressors help to train the body’s ability to adapt more efficiently to environmental and metabolic demands, and thus supporting healthy weight management.

From a metabolic standpoint, sauna sessions can also temporarily increase energy expenditure. While estimates vary, heat exposure does raise the heart rate and burn calories. However, it is important to note that most immediate weight loss after sauna use is water loss through sweating, not fat loss. However, with consistent exposure to contrast therapy, healthy weight management is a positive side effect.

Metabolic health, inflammation and the connection with weight regulation

Healthy weight management is not only about calories, it is also strongly influenced by insulin sensitivity, inflammation, stress hormones (like cortisol), sleep quality and nervous system balance. And this is where contrast therapy may have indirect benefits.

Stress and the nervous system

Both sauna and cold exposure influence the autonomic nervous system. Sauna use tends to promote parasympathetic recovery states after exposure (that relaxed feeling), while cold exposure stimulates alertness and catecholamine release (that buzzed feeling).

Over time, this ‘training effect’ can improve stress resilience, which is important because chronic stress is strongly linked to weight gain patterns, especially around stubborn abdominal fat storage.

The incredible effect of Heat Shock Proteins

Heat Shock Proteins (HSPs) are often described as the body’s cellular ‘repair crew’ or ‘maintenance team’. Produced in response to stressors like heat exposure in the sauna, they help protect cells by repairing damaged proteins, clearing away dysfunctional cellular material and supporting healthy cellular function. Scientists sometimes refer to them as molecular chaperones because they help guide proteins back into their proper shape and function after stress.

Research suggests that repeated heat exposure increases HSP expression and supports pathways linked to improved insulin sensitivity, vascular function and metabolic resilience.

We know that chronic low-grade inflammation is strongly associated with metabolic conditions such as obesity, insulin resistance and type 2 diabetes. Interestingly, research has shown that the body’s heat shock response can become impaired in these conditions, potentially contributing to ongoing and cumulative inflammatory dysfunction.

A review of the use of sauna in the context of those living with type 2 diabetes stated ‘Heat therapy is a promising and inexpensive tool for the treatment of obesity and diabetes’ and the authors recommended enjoying the sauna at 80-100°C for 15 minutes, three times a week, for three months as a safe method.

Cold exposure, meanwhile, has been explored for its potential to activate glucose uptake in muscle tissue and increase energy demand.

When practised together, heat and cold exposure help to support a healthier inflammatory balance and improved metabolic function. While these therapies are not a replacement for nutrition, movement or sleep, reducing chronic inflammatory burden and improving stress resilience can indirectly support healthier weight management.

Energy, mood and behavioural effects

One of the most consistent benefits reported in both sauna and cold exposure research is improvement in mood, energy and perceived wellbeing.

Sauna use is frequently associated with relaxation, reduced perceived stress and improved sleep quality. Cold exposure, on the other hand, has been linked to increased alertness, resilience and dopamine release, effects explored further in our recent blog post on cold therapy and mood.

This combination may be particularly relevant for weight management because better sleep supports appetite regulation hormones, improved mood reduces emotional eating tendencies, higher energy levels increase movement and daily activity.

In other words, contrast therapy may support the behavioural side of health more than the purely physiological side.

A balanced view: what it can and cannot do

It is important to stay grounded in what the evidence currently supports.

Contrast therapy:

✔ Supports circulation, recovery and cardiovascular function
✔ Improves stress resilience and mood
✔ Increases energy expenditure (modestly)
✔ Supports healthy lifestyle habits and consistency

But it does NOT:

✘ Directly cause significant fat loss on its own
✘ Replace exercise or nutrition fundamentals
✘ Act as a standalone weight-loss intervention

The most realistic way to view contrast therapy is as a supportive metabolic tool, not a solution.

Final thoughts

Contrast therapy sits at the intersection of ancient practice and modern wellness science. While the research is still developing, what we do know is compelling: both heat and cold exposure influence the cardiovascular system, nervous system and metabolic processes in meaningful, but nuanced ways.

For healthy weight management, the greatest value may not lie in calorie burn alone, but in the way these practices support energy, lowers stress, allows for physical recovery and adds to consistent healthy behaviours.

In that sense, contrast therapy is less about ‘losing weight’ and more about helping the body function in a more balanced, adaptable and efficient way, which is ultimately what sustainable health is built on.