How brown fat can help you lose weight.
Brown fat, also known as brown adipose tissue (BAT), is a type of body fat that is found in small amounts in humans and other mammals. Unlike white fat, which stores excess energy in the form of triglycerides, brown fat burns calories to generate heat. This makes it an important tool for regulating body temperature and weight.
It's no secret that obesity is on the rise in countries across the globe. Almost 40% of adults are considered overweight while one-tenth are considered obese, and the numbers continue to climb with gradual increases in children.[1] Many people turn to diet and exercise in an attempt to lose weight, but this can be difficult for those who are already struggling with their weight.
There may be another solution: brown fat.
What is brown fat and how does it work?
Brown fat is a type of body fat that is found in small amounts in humans and other mammals. Unlike white fat, which stores excess energy in the form of triglycerides, brown fat burns calories to generate heat. This makes it an important tool for regulating body temperature and weight.
Brown adipose tissue has a dense concentration of mitochondria, lovingly referred to as the 'powerhouse of the cell.' This type of fat also expresses something known as uncoupling protein 1 (UCP1) which is found within the mitochondria. Through a chemical process, UCP1 releases energy in the form of heat, something known as thermogenesis.
In human adults, brown fat is mostly found in the neck and upper back. Though it can also be found in other areas of the body including major arteries, esophagus, abdominal wall and surrounding major organs.[2] It makes up about 7% of all body fat in lean adults, but its quantity can vary significantly from person to person.[3] Brown fat activity has been shown to decrease with age and obesity, and it may play a role in the development of associated conditions.[3,4]
What is BAT's origin story?
It is believed that brown fat developed in response to periods or torpor or hibernation. The warmth generated by these metabolically active cells helped mammals generate enough heat for basic biological processes. For example, arctic ground squirrels entering torpor used eight times more energy to maintain body temperature - hence the fattening up during the autumn months! [5]
Though what about humans? That is a complicated processing involving myf-5-expressing progenitors and...let's skip to the good part. Infants tend to show heightened levels of BAT because they lack significant skeletal muscle mass.[6] As humans age, shivering can help to maintain core body temperature when adolescents and adults are exposed to cold. However, there are better ways than sitting outdoors in winter to activate thermogenesis.
How can you harness BAT in your own weight management journey?
If you want to help your body and wallet, turning the temperature down at night is a passive way to manage weight. Over four months, people sleeping in a room set at 19°C (66°F) had a 42% increase in total BAT and 10% greater metabolic activity. Those sleeping in warmer conditions inactivated brown fat, causing metabolic activity to fall.[7]
Don't want to wait four months? A group from the Medical University of Vienna showed people exposed to cold for 90-minutes burned 15% more calories over the next two hours.[8]
Other research in healthy young men showed cold exposure helped redistribute adipose tissue. Losses occurred in areas that were once dense with lipids, while lipid poor areas saw a net gain. The scientists hypothesized that this could be due to fatty acid uptake in certain regions to generate heat.[9]
"Lipid mobilization within the brown adipose tissue depot occurred rapidly in response to a cold stimulus."
Consider gradually turning the shower down as you get to the end, lower the temperature of your residence and consider a cooler swim as before summer strikes.
Think of your daily pattern of eating
Fasting can be an effective way to help manage weight when done safely, can be a healthy addition to a routine diet. Some of the most well-known cultures and religions include fasts in their celebrations. Whether Yom Kippur, Ramadan or Lent, millions of people experience periods of extended fasting with no ill effects.[10]
When you fast for an extended period, your body starts to burn stored fat for energy. Fasting can be a safe and effective way to manage weight amongst other interventions. A regulated health professional can help you determine if fasting is right for you. This might include checking blood glucose, a lipid panel and kidney and liver function to name a few.
The research looks at something known as EODF or every other day fasting which seems to stimulate the conversion of white fat to beige fat, a mix of white and brown, in mice. This occurs in part because of alterations to the microbiome, contributing to brown fats benefits for insulin resistance and obesity.[11] More research needs to be done in humans, but regardless of the benefits on weight, authorities like the American Heart Association include intermittent fasting as one of the dietary ways to prevent cardiovascular diseases. They recognize its ability to improve lipid profiles, improve insulin sensitivity and reduce insulin resistance.[12]
So, what does this all mean for you trying to manage your weight loss goals?
Targeting BAT is a viable option that you can enhance through simple changes in your daily routine. Cold exposure and fasting are two methods of stimulating brown fat activity. Fasting has been shown to have other health benefits as well. Talk with a regulated health professional to see if these are a good option for you.
References
World Health Organization. Global action plan on physical activity 2018-2030: more active people for a healthier world. World Health Organization, 2019.
Sacks, Harold, and Michael E. Symonds. "Anatomical locations of human brown adipose tissue: functional relevance and implications in obesity and type 2 diabetes." Diabetes 62.6 (2013): 1783-1790.
Worku, Misganaw Gebrie, et al. "Prevalence and associated factor of brown adipose tissue: systematic review and meta-analysis." BioMed research international 2020 (2020).
Yoneshiro, Takeshi, et al. "Recruited brown adipose tissue as an antiobesity agent in humans." The Journal of clinical investigation 123.8 (2013): 3404-3408.
Williams, Cory T., et al. "Hibernating above the permafrost: effects of ambient temperature and season on expression of metabolic genes in liver and brown adipose tissue of arctic ground squirrels." Journal of Experimental Biology 214.8 (2011): 1300-1306.
Lidell, Martin E. "Brown adipose tissue in human infants." Brown adipose tissue (2018): 107-123.
Lee, Paul, et al. "Impact of Chronic Cold Exposure in Humans (ICEMAN) Study: Evidence for Brown Adipose Tissue Plasticity Modulating Glucose Metabolism in Humans." ENDOCRINE REVIEWS. Vol. 35. No. 3. 2055 L ST NW, SUITE 600, WASHINGTON, DC 20036 USA: ENDOCRINE SOC, 2014.
Kulterer, Oana C., et al. "The presence of active brown adipose tissue determines cold-induced energy expenditure and oxylipin profiles in humans." The Journal of Clinical Endocrinology & Metabolism 105.7 (2020): 2203-2216.
Coolbaugh, Crystal L., et al. "Cold exposure induces dynamic, heterogeneous alterations in human brown adipose tissue lipid content." Scientific reports 9.1 (2019): 1-13.
Trepanowski, John F., and Richard J. Bloomer. "The impact of religious fasting on human health." Nutrition journal 9.1 (2010): 1-9.
Li, Guolin, et al. "Intermittent fasting promotes white adipose browning and decreases obesity by shaping the gut microbiota." Cell metabolism 26.4 (2017): 672-685.
St-Onge, Marie-Pierre, et al. "Meal timing and frequency: implications for cardiovascular disease prevention: a scientific statement from the American Heart Association." Circulation 135.9 (2017): e96-e121.
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