Tag Archives: lifespan

Weight Loss

Some basic reasoning tells us that cold showers can assist in weight loss. Consider the acute effects of a cold shower. The water hits the skin and almost immediately the body jump starts; blood flow increases, muscles harden, and heart rate increases. All of these things require energy.

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

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

Strengthen Immune System

immunesystemCold showers are sometimes touted as a preventative tonic for colds, flu, and infections. However, are these reported benefits just a placebo effect – the power of suggestion, or do cold showers have a direct and measurable effect on our immunity?

Once again, studies show at least some support for the popular wisdom. An experiment in Prague studied the effect of cold water immersions on athletic young men. They immersed them in water at 14 °C (57 °F), three times a week for six weeks. They concluded that the immersions activated the immune system “to a slight extent”.

Among many changes, they saw increased levels of two types of white blood cells: monocytes and lymphocytes. While certain lymphocytes are instrumental in eliminating bacteria, viruses, and toxins, monocytes are indirectly responsible for the engulfing and consuming of pathogens and foreign materials [2,3].

Considering these effects, it’s no surprise that mice exposed to 8 days of brief cold water stress survived significantly longer when exposed to the intracellular parasite, Toxoplasma gondii [4].

So, cold showers can help keep away the sniffles, but who knows what other nasty virus or pathogen you might also happen to ward off?

[1] Immune system of cold-exposed and cold-adapted humans.
[2] http://en.wikipedia.org/wiki/Lymphocyte
[3] http://en.wikipedia.org/wiki/Monocyte
[4] Cold stress-induced modulation of cell immunity during acute Toxoplasma Gondii infection in mice.