Kids have brown fat. Why don't adults?
Summary
The U.S. has the highest obesity rates globally, with over 70% of adults classified as overweight or obese.
Obesity contributes to serious health conditions like diabetes and heart disease, with healthcare costs exceeding $340 billion annually.
Brown fat, present at birth and retained in small amounts in adults, burns energy through thermogenesis and plays a key role in metabolic health.
Adults with higher brown fat levels show reduced metabolic disease, lower BMI, and possibly longer lifespans, making it a promising obesity treatment target.
Frigid temperature exposure activates brown fat, suggesting cold-induced thermogenesis as a natural method for fat loss and metabolic regulation.
Metabolic Dysfunction Among American Adults
The United States is home to more obese people than any other country in the world. According to the Centers for Disease Control, the vast majority of American adults are either overweight (32.5%) or obese (39.8%) .
Fewer than just 3 out of 10 Americans could be considered healthy or underweight.
If obesity were an infectious disease, it would be a pandemic worse than flu, worse than AIDS, worse than malaria, worse than pneumonia. In fact, the new medical term for a constellation of risk factors related to obesity is metabolic disease, and it results in a plethora of deadly consequences such as:
high blood pressure
high cholesterol
Type 2 diabetes
cardiovascular disease
stroke
gallbladder disease
osteoarthritis
sleep apnea
some cancers
In addition to the loss of health and quality of life, the financial costs are staggering. Obesity-related healthcare expenditures in the United States exceeded $340B in 2013, and have continued to grow since.
Perhaps it is no surprise that the US weight loss industry is growing fast, too. Americans spent over $72B trying to slim down in 2018 -- and yet they're still getting fatter. In addition to extreme cases, some people undergo gastric bypass surgery to reroute food around the stomach, interrupting digestion, curbing appetite, and forcing caloric deficit in an effort to reduce fat.
Baby Fat for Grown Ups
There is a better, simpler way--and the key is understanding "baby fat."
Human babies are born about 15% fat (by body mass) -- fatter than any other mammalian species. Moreover, they are endowed at birth with what is called brown adipose tissues (BAT), or brown fat, that plays a special role in keeping the human infant warm. The brown fat cells are packed with additional mitochondria organelles for burning lipids stored by white fat cells in a process called thermogenesis.
As human children grow, they typically lose brown fat cells, which is a process we all understand as "growing out of it". Some famous celebrities were fat children who grew up to be thin, fit adults. For example, Jerry O'Connell played the fat kid in the 1986 movie Stand by Me when he was 11 years old. Ten years later, he was almost unrecognizable as the athletic college quarterback in Jerry Maguire.
Nevertheless, O'Connell's experience is exceptional.
Most people lose brown fat, only to gain white fat. In fact, brown fat is so rare in adult Americans that until new techniques for its detection were developed 10 years ago, medical scientists thought adults didn't have any brown fat at all.
Then, in 2009 researchers discovered that small reserves of brown fat at the back of neck exist in all of us. Turns out the adult human body both keeps a small amount of brown fat from infancy, and retains the capacity to recruit more.
Higher levels of brown fat are associated with decreased incidence of metabolic disease, lower BMI, increased bone health, and possibly even longer life spans, so it's no wonder medicine has taken an interest. It seems possible that the human body itself may be capable of doing what modern medicine has thus far been unable to -- find a cure for the obesity epidemic -- because unlike white fat, which stores energy, the purpose of brown fat is to burn it.
And the best way to retain or recruit brown fat is by deliberate cold exposure.
Not just mild cold. To reap the benefits of brown fat, regular exposures to frigid temperatures are required.
Being only ten years since the re-discovery of brown fat in adults, the science is still in its infancy and there is a lot that remains to be studied. For example, brown fat can also be activated by catecholamines, which are stress hormones released during the sympathetic nervous system’s “fight or flight” response. This is particularly interesting to ice bathers, given that both stimuli -- cold exposure and acute stress response -- are present in the ice bathing experience.
This could mean that ice bathing could be doubly effective at activating and generating brown fat and, thus, doubly effective as a therapy for fat loss. Despite the billions of dollars invested in the fight against metabolic diseases, modern medicine isn't any closer to finding a magic pill or surgical treatment that will permit constant thermal comfort and modern diets and lifestyle without deleterious metabolic effects. Ong, et al (2018) suggests that science needs a new, uniform cold exposure protocol to better understand the effects of cold exposure and how brown fat can be harnessed to develop treatment protocols for obesity.
Morozko isn't waiting for the pharmaceutical industry to encapsulate cold exposure in a pill. Our experiences of weight loss, health restoration, and metabolic regulation have been so profound that we will continue to experiment with our own protocols for cold exposure, diet, fasting, and metabolic regulation that have proven to give positive results.
References
Atzmon G, Pollin TI, Crandall J, Tanner K, Schechter CB, Scherer PE, Rincon M, Siegel G, Katz M, Lipton RB, Shuldiner AR. Adiponectin levels and genotype: a potential regulator of life span in humans. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences. 2008 May 1;63(5):447-53.
Betz MJ, Enerbäck S. Targeting thermogenesis in brown fat and muscle to treat obesity and metabolic disease. Nature Reviews Endocrinology. 2018 Feb;14(2):77-87.
Biener A, Cawley J, Meyerhoefer C. The high and rising costs of obesity to the US health care system. Journal of General Internal Medicine. 2017 Apr;32:6-8.
Chondronikola M, Sidossis LS. Brown and beige fat: From molecules to physiology. Biochimica et Biophysica Acta (BBA)-Molecular and Cell Biology of Lipids. 2019 Jan 1;1864(1):91-103.
Cypess AM, Kahn CR. Brown fat as a therapy for obesity and diabetes. Current Opinion in Endocrinology, Diabetes and Obesity. 2010 Apr 1;17(2):143-9.
Ejima K, Aihara K, Nishiura H. Modeling the obesity epidemic: social contagion and its implications for control. Theoretical Biology and Medical Modelling. 2013 Dec;10:1-3.
Gordon K, Blondin DP, Friesen BJ, Tingelstad HC, Kenny GP, Haman F. Seven days of cold acclimation substantially reduces shivering intensity and increases nonshivering thermogenesis in adult humans. Journal of Applied Physiology. 2019 Jun 1;126(6):1598-606.
Lidell ME. Brown adipose tissue in human infants. Brown adipose tissue. 2019:107-23.
Mc Z. The presence of UCP1 demonstrates that metabolically active adipose tissue in the neck of adult humans truly represents brown adipose tissue. FASEB J. 2009.
Wang Q, Zhang M, Ning G, Gu W, Su T, Xu M, Li B, Wang W. Brown adipose tissue in humans is activated by elevated plasma catecholamines levels and is inversely related to central obesity. PloS One. 2011 Jun 20;6(6):e21006.
About the Author
Thomas P Seager, PhD is an Associate Professor in the School of Sustainable Engineering at Arizona State University. Seager co-founded the Morozko Forge ice bath company and is an expert in the use of ice baths for building metabolic and psychological resilience.
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