Do ice baths help with weight loss?
Cold exposure is one of the hot topics. Cold plunges are supposed to reduce your anxiety, help you recover better, and even lose fat.
How?
When we are exposed to cold, our body needs to increase metabolism to keep us warm. But what captured scientists is that cold promotes turning white fat, an energy storage, into brown fat, which is metabolically active.
Further research has shown that short-term exposure to cold activates brown fat and that could be used for fat loss.
Effects of Cold Exposure on Energy Expenditure
There are three ideas on how cold exposure could contribute to fat loss.
Our brain keeps the body’s temperature within a small range. In a cold environment, the body uses energy to keep us warm and so it increases energy expenditure:
- Shivering
- Non-shivering warming
However, there are differences between short and intense cold exposure (cold plunges in water) and mild but longer cold exposure (usually at about 15°C).
Shivering
To increase energy expenditure by shivering, the core temperature needs to decrease. The body wants to get back to a neutral temperature, so it starts to shiver.
Cold Water has higher heat transfer and results in faster heat loss. That’s what is used in most studies.
Water gets your cold temperature down faster, but it’s about getting the core temperature down not skin temp!
In a study (Néma J. et al 2023) on Czech male soldiers reported a reduction of visceral fat (5.5%), waist circumference, and lower anxiety. The study lasted for 8 weeks. The protocol they used was immersion of a whole body for over 30s in open water with a temperature lower than 6°C more than 1/week. Participants were also instructed to take cold showers <10°C more than 4x/week.
However, the study had big design flaws.
Only the intervention group received a talk about the benefits of cold exposure, which introduces a placebo effect.
Fat loss accounted for less than 5% between the cold exposure group and the control group, which could be attributed to other lifestyle changes in the intervention group that they did not control.
Non-shivering mechanism
When the temperature is low, but not so low that the body doesn’t need to shiver, it constricts blood vessels in the skin to reduce heat losses. But cold also triggers a mechanism called fat browning, which signals the body to produce brown fat tissue that keeps us warm without shivering.
Browning of fat
The primary task of white adipose tissue (WAT) is the storage of lipids. However, ‘beige’ adipocytes also exist in WAT. Beige adipocytes burn fat and dissipate the energy as heat, but their abundance is diminished in obesity. Stimulating beige adipocyte development, or WAT browning, increases energy expenditure and holds the potential for combating metabolic disease and obesity.
A study compared Wim Hof and his brother to test the browning of fat. They found no differences between Wim and his twin brother, who was not accustomed to cold exposure (13C).
They did two and a half hours of mild cold exposure (12–13°C).
Increased energy expenditure to a similar extent in the cold (A: from 1.31 kcal/min to 1.84 kcal/min versus B: from 1.31 kcal/min to 1.85 kcal/min)., resulting in a Cold-Induced Thermogenesis of 40.1% and 41.9% for subject A and B, respectively. These values were clearly higher compared to the increase in energy expenditure we observed during mild cold experiments in young adult men (interquartile range: 7.2–18%; 95th percentile: 25.7%. The Cold-Induced Thermogenesis in the current experiment is not equal to classical Non-Shivering Thermogenesis, as the twin used respiratory muscle isometric contraction to generate heat as well. (Vosselman MJ et al., 2014)
As observed by van der Lans AA, et al, young men and women exposed to mild cold (15–16°C) conditions for ten consecutive days, increased both BAT activity and Non-Shivering Thermogenesis. It is thus likely that long periods of mild cold exposure are more effective in increasing BAT activity and Cold-Induced Thermogenesis than single bouts of extreme cold exposure.
As observed by van der Lans AA, et al, young men and women exposed to mild cold (15–16°C) conditions for ten consecutive days, increased both BAT activity and Non-Shivering Thermogenesis. It is thus likely that long periods of mild cold exposure are more effective in increasing BAT activity and Cold-Induced Thermogenesis than single bouts of extreme cold exposure.
Long exposure to cold environments
In cold weather, metabolism increases to maintain the body temperature to adapt to the cold environment. Could living in cold environments increase energy expenditure more than a short immersion in cold water?
Japanese women had their resting metabolic rate increased (~300kcal, which was about 20% difference) in winter months. (Tanaka et. al 2022)
In a study on seasonal variations in BMR, Oshiba reported that the basal metabolic rate in Japanese males increased by 6% when the air temperature decreased from 15 to 5 °C. In their paper, they also mentioned other studies where a the difference between Basal metabolic rate in summer and in winter months was about 17%. (31.5 – 37 cal/m^2/h).
They also compared metabolism when sleeping in a cool room 6.5-12°C to a standard room temperature 25°C. There were no significant differences between the two.
They also found that it takes about a week for the basal metabolic rate to adapt to the cold environment.
The basal metabolism changes 6.6% by 10°C change of environmental temperature (or 2.4 Cal per 10°C).
Practical problems:
To burn extra calories using cold, you need to either shiver or spend hours daily in cool environment to produce and actively use BAT.
The average mass of BAT ranges from 50 to 70 g in adult humans. Such an amount of active BAT could increase daily energy expenditure by about 170 kcal. It was calculated that 63 g of fully activated supraclavicular BAT would utilize an amount of energy equivalent to 4.1 kg of WAT. (Maliszewska K., 2021)
Appetite follows increased energy expenditure.
We can observe that swimmers tend to spontaneously eat more than other athletes. A small study (White LJ,, et. al 2005) compared effects on appetite after exercising in water. Two groups of young men exercised in water for 45 minutes, and then had a meal. Those exercising in 33°C water, consumed about 517 kcal, while those who exercised in 20°C water consumed about 877 kcal of food.
A meta-analysis (Millet J. et al., 2021) on the effects of temperature on appetite confirmed these results. They found that after cold exposure, participants consumed on average 179 kcal more calories if not exercising, and 251 kcal more when exercising (45 minutes) in cold water (19 ± 3 °C) compared to neutral temperature (32 ± 3 °C) water.
Summed up, the extra energy you would burn being in a cold environment would be nullified, or even overcompensated by increases in appetite.
In my opinion, if you want to do ice baths or spend time in cold, do it for mental toughness, or to boost your immunity, not for fat loss.
There are other, more effective ways to create a caloric deficit through diet, and lifestyle changes.
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Resources
- Millet J, Siracusa J, Tardo-Dino PE, et al. Effects of Acute Heat and Cold Exposures at Rest or during Exercise on Subsequent Energy Intake: A Systematic Review and Meta-Analysis. Nutrients. 2021;13(10):3424. Published 2021 Sep 28. doi:10.3390/nu13103424
- Néma J, Zdara J, Lašák P, et al. Impact of cold exposure on life satisfaction and physical composition of soldiers. BMJ Mil Health. Published online January 4, 2023. doi:10.1136/military-2022-002237
- OSIBA S. The seasonal variation of basal metabolism and activity of thyroid gland in man. Jpn J Physiol. 1957;7(4):355-365. doi:10.2170/jjphysiol.7.355
- Šrámek, P., Šimečková, M., Janský, L. et al. Human physiological responses to immersion into water of different temperatures. Eur J Appl Physiol 81, 436–442 (2000). https://doi.org/10.1007/s004210050065
- Tanaka N, Okuda T, Shinohara H, Yamasaki RS, Hirano N, Kang J, Ogawa M, Nishi NN. Relationship between Seasonal Changes in Food Intake and Energy Metabolism, Physical Activity, and Body Composition in Young Japanese Women. Nutrients. 2022 Jan 24;14(3):506. doi: 10.3390/nu14030506. PMID: 35276865; PMCID: PMC8838489.
- van der Lans AA, Hoeks J, Brans B, et al. Cold acclimation recruits human brown fat and increases nonshivering thermogenesis. J Clin Invest. 2013;123(8):3395-3403. doi:10.1172/JCI68993
- Vosselman MJ, Vijgen GH, Kingma BR, Brans B, van Marken Lichtenbelt WD. Frequent extreme cold exposure and brown fat and cold-induced thermogenesis: a study in a monozygotic twin. PLoS One. 2014;9(7):e101653. Published 2014 Jul 11. doi:10.1371/journal.pone.0101653
- White LJ, Dressendorfer RH, Holland E, McCoy SC, Ferguson MA. Increased Caloric Intake Soon after Exercise in Cold Water. International Journal of Sport Nutrition and Exercise Metabolism. 2005;15(1):38-47. doi:10.1123/ijsnem.15.1.38
- Millet J, Siracusa J, Tardo-Dino PE, et al. Effects of Acute Heat and Cold Exposures at Rest or during Exercise on Subsequent Energy Intake: A Systematic Review and Meta-Analysis. Nutrients. 2021;13(10):3424. Published 2021 Sep 28. doi:10.3390/nu13103424