If its cold out, and you want to lose weight, don’t put on that jacket. Or, based on a current trend, you could pay money to stand or sit in cold air as a weight loss treatment.
In short, the suggestion is that if we expose our bodies to cold, but not freezing temperatures (62 Fº or 16-17 Cº), we lose weight. But, how could this work?
A review published this year, cleverly named ‘Breaking BAT’, or ‘brown adipose tissue’, gives us the most recent update on whether cold air for weight loss is plausible.2
Mammals, including us, have what is called brown fat (or brown adipose tissue = BAT). As babies we have quite a bit in our bodies, but it declines as we age. As adults, what we have left is located around our neck, between our shoulder blades, and around blood vessels of the thorax.
Brown fat is different than white fat, which is the fat we are most familiar with – under the skin. The brown color comes from the many mitochondria in the cell, much like dark meat versus white meat.
“The most important feature of brown fat is the capability to oxidize substrates to produce heat for facultative thermogenesis, which is required to maintain body temperature under conditions below thermoneutrality.”2
What does that mean? In other words, brown fat can create heat when the body gets cold to help maintain body temperature. This heat warms our body, so we do not have to shiver.
However, "the most crucial point is whether the capacity for energy expenditure in these depots is high enough to shift energy expenditure compared to other means like exercise or food restriction and bring about tangible therapeutic benefits.”2
Recent estimations have fully activated brown fat expending only 25 to 50 calories a day.1 For comparison, a 165 lb person would expend about:
- 20 calories watching 20-minutes of TV,
- 64 calories taking the stairs to the 4th flloor,
- 100 calories riding a bike for 20-minutes, or
- 740 calories playing soccer for 45-minutes.
In addition, you can see the food calorie equivalents on the bottom row of the figure.
|From Warner & Mittag (2016)|
Yet, these estimations might even be OVER estimating, since “the first studies using real life conditions rather than algorithms now estimate that human [brown fat] activated by mild cold exposure would contribute expenditure of 15–25 kcal/day.”2
“These findings are rather discouraging in the context of obesity treatment as an overweight person would require about 15 years of fully active [brown fat] to melt off 20kg [44 lbs] of fat.”2
This becomes even less feasible when considering that brown fat...
1. is more difficult if not impossible to recruit in obese people,
2. highly variable between individuals,
3. and that any increase in energy expenditure is often met by increased compensatory food intake.
So, it is not looking too well for an expensive cold air spa day. Even worse, it is not sufficient to activate the brown fat on a single occasion, such as one visit to the spa.
Even when you leave the spa, “the additional thermogenesis [heat production] will cease as soon as the individual returns to the usual thermoneutral [room temperature] environment...”2
“This was clearly demonstrated in a recent study, where [brown fat] was activated by cold exposure (15–16º C; 59-61º F) for 6 hours daily for 10 days, but resting metabolic rate was not elevated when the patients returned to thermoneutrality [room temperature].”2-3
Oh, and don’t forget the possible side effects, including increased sweating and hyperthermia, hunger and even cardiovascular problems, such as arterial plaque formation.
With all that being said, I think, for now, we have to say that cold air being effective for weight loss is UNLIKELY.
- Devlin, M. J. (2015). The “Skinny” on brown fat, obesity, and bone. American Journal of Physical Anthropology, 156(S59), 98-115.
- Warner, A., & Mittag, J. (2016). Breaking BAT: Can browning create a better white? Journal of Endocrinology, 228(1), R19-R29.
- van der Lans, A. A., Hoeks, J., Brans, B., Vijgen, G. H., Visser, M. G., Vosselman, M. J., ... & Schrauwen, P. (2013). Cold acclimation recruits human brown fat and increases nonshivering thermogenesis. The Journal of Clinical Investigation, 123(8), 3395-3403.
*NOTE: In the video, citation '1' is actually referring to reference '2'. Sorry.