A lot of reports suggest taking a cold bath, or shower, could lead to dramatic weight loss. These reports have been around for some years but have recently been on the increase, fuelled by our constant obsession with alternative ways to lose weight.
The science is quite interesting: brown fat, which is mostly located in the neck region and also around collarbones, is activated when we are cold to warm us up. Unlike unhealthy white fat which builds up around our waistlines and thighs, brown fat is derived from muscle and expends energy during the heating process. Once activated, brown fat actually burns white fat and glucose. Given the link between white fat and obesity, this is surely a good thing.
A direct correlation exists between the activation of brown fat and metabolic measures of good health. Slender people have more brown fat than those overweight, and the youngest amongst us have more than the elderly. Those with normal blood sugar levels also benefit over those with high blood sugar. Having said that, levels of brown fat varies, even between those with the same profile. In fact, brown fat remaining active in adults is a relatively recent discovery. It was originally thought that this fat only did its job during our formative years.
Several trials make astonishing claims regarding brown fat. One article I read estimates that just 50g of brown fat can burn 20% of your daily calorific intake. Sounds impressive! Another interesting development is that we can probably convert harmful white fat into brown fat simply by exercising. During exercise, a recently discovered enzyme called irisin triggers this conversion. Though trials have only been performed on animals up to now, it is thought the same phenomenon would occur in humans as we share the same protein.
Another trial involving a group of adults wearing cold suits, found that they lost an additional 250 calories over a three hour period of inactivity, than they would have done otherwise. The suits were set at a temperature which would not cause the subjects to shiver, which could have accounted for some of the extra calories burned.
Unfortunately, aging has a strong negative determinant on brown fat and activity, which means that someone of my age would have little or no benefit from submerging themselves in cold water. Trials are on-going to establish how beneficial our brown fat is to us as we get older, but it is clear that it is still active into young adulthood. The reduced effectiveness of brown fat, to some extent, explains why we put weight on as we get older and find it difficult to shift.
Using cold water to burn extra calories seems to be a good way to burn extra calories if you already have a good diet and exercise regularly. New research is also looking at how we can increase our brown fat levels through medical intervention. A protein called BMP-7 was trialled on mice and found to be a growth factor for brown fat.
Discovering brown fat still being active in adults has led to some interesting discoveries and new trials are ongoing. I just hope they find a way to re-activate it in those past a certain age so I can benefit too!