Alexa Fleckenstein, M.D., author of Health20, has a few things to say about cold showers. Within the book, she writes:

“Cold water can do more than just wash away sweat, dirt, old skin cells, bacteria, and viruses:

What a Cold Shower Can Do For You

1. Enhance immunity against infections and cancer

2. Give your glands (thyroid, adrenals, ovaries/testes) a boost, improving hormonal activity

3. Jump-start your mood and motivation

4. Crank up your metabolism to fight type 2 diabetes, obesity, gout, rheumatic diseases, depression, and more

5. Normalize your blood pressure

6. Decrease chronic pain

7. Train and improve your blood circulation

8. Detoxify your body

9. Fight fatigue

10. Strengthen exhausted, irritable nerves

11. Rejuvenate, heal, and tone the skin

12. Deepen your breathing

13. Help with insomnia

14. Improve kidney function

15. Reduce swelling and edema

16. Improve lymphatic circulation, thereby increasing immune function

17. Reduce stress by regulating your autonomic nervous system

18. Regulate temperature, fighting chronically cold hands and cold feet and excessive sweating

19. Keep your hair healthy

20. Improve hemorrhoids and varicose veins

21. Reduce aches and pains”

Just thought you’d like to know.

Babies typically have a constitution of 5% brown fat. It is one of their main mechanisms for staying warm.

Many people report that they feel warmer throughout the day after taking a cold shower or bath. This could partly be due to enhanced circulation, but the stimulation of brown fat also seems a likely cofactor.

Brown fat is one of two types of fat in the body – the other being white fat, or what we normally just refer to as “body fat”. While white fat should be kept to a minimum, brown fat is beneficial because it helps burn calories and generate body heat. A study at the University of Maastricht in the Netherlands revealed that obese people have less brown fat than lean people [1].

A cold shower could be a good way to stimulate the body’s supply of brown fat. A branch of the aforementioned university found that in men, exposure to chilly temperatures increased the metabolic rate of brown fat 15-fold. Sustaining this rate alone could help a person shed 9 pounds a year. Women typically have twice as much brown fat as men [1].

In a Chinese experiment involving voles exposed to a 5° C environment, they found that the “thermogenic capacity” of brown fat increased; the cold-exposed voles had a higher content of uncoupling protein 1 in their brown fat, increasing their ability to convert stored calories into heat [2].

However, in one small study of six men, the researchers did not find that their adaption to cold was facilitated by brown fat [3]. Hopefully future studies will find the most favorable conditions for activating brown fat and the precise benefits we can expect.

[1] Brown Fat: Don’t Try To Burn It
[2] Cold exposure does not decrease serum leptin concentration, but increases energy intake and thermogenic capacity in pregnant Brandt’s voles (Lasiopodomys brandtii).
[3] Effects of acclimitazation to cold baths on men’s responses to whole-body cooling in air.

It may help to think of the body as a heat engine. A typical heat engine utilizes a hot reservoir and a cold reservoir to run a motor, as in the diagram below. Only, instead of a motor, the body runs various metabolic processes.

Why Your Body is Warmer Than the Environment

Like a heat engine, the body must transfer heat to the environment. Even on a blistering hot day, we transfer latent heat to the air by sweating. Internal body temperature is the “hot reservoir” of the heat engine, while the “cold reservoir” is the air (or water) that surrounds the body. Without this transfer of heat, the energy of all our metabolic processes would have nowhere to go.

The key is that the metabolic output (W), equals the amount of heat flowing from the hot to cold reservoir. Taking a cold shower or bath forces you to burn more energy. And by estimating water temperature, you could calculate approximately how much.

In a 2.5 year experiment, rats of equal age were gradually accustomed to standing in cool water (at 23° C, 73° F) until they were standing in it 4 hours per day, 5 days per week. Even though the rats ingested 44% more food than the control group, their body weight was significantly lower. Incidentally, their lifespan was also slightly longer (by approximately 5%), and they had significantly fewer tumor formations [1].

This also trains your physiology to deal with colder temperatures, raising your resting metabolism. This is similar to the effect of physical exercise. The only difference is that while working out raises it through a direct stimulus to metabolism (through will power), showering in cold water is more of an indirect stimulus.

[1] http://www.ncbi.nlm.nih.gov/pubmed/3781978

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