Body fat is often associated with a sedentary lifestyle, a high-calorie diet, and an unhealthy body. For this reason, many sports enthusiasts seeking optimal health try to keep a low body fat percentage to improve health and avoid diseases.
However, the scientific community has discovered that the human body does not only have the “bad” fat that builds up and causes health problems. Instead, our bodies also have the “good” fat called brown fat that benefits our well-being. This article provides the latest information about brown fat and how it helps with metabolism.
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Brown Fat Can Accelerate Metabolism to Help Treat Metabolic Disorders
What Is Brown Fat?
Brown fat, also known as brown adipose tissue, is metabolically active fat that develops in small amounts in the body. Brown fat is a unique type that works opposite to the “bad” white fat by increasing energy expenditure and producing heat.
So, where is brown fat located in the body? Unlike white fat, brown fat is only present sporadically in specific body areas. For example, it can be found in the shoulder blades, surrounding the neck, kidneys, and along the spinal cord.
Brown Fat Vs. White Fat: What’s the Difference?
Brown fat is different from white fat. White fat, generally referred to as “bad” fat, builds up when you consume excess calories and is mobilized when there is a calorie deficit. White fat is associated with diabetes, heart disease, stroke, and artery disease.
In contrast, brown fat is packed with iron-rich mitochondria, which gives brown fat its color. This brown fat breaks down stored energy like sugar and white fat to produce heat. So, instead of storing calories, brown fat burns them and heats the body when necessary.
How Do We Get Brown Fat?
Everyone is born with some brown fat in their body.
Brown fat is present in large amounts (about 5 percent of the body weight) during infancy in a newborn. Brown fat allows an infant to generate heat to maintain the body temperature, as a newborn has not developed the ability to shiver for heat generation during this stage. This mechanism suggests brown fat as a “built-in” heater in the neonatal period.
However, the body loses most brown fat with age as grown humans form a natural shiver response to cold temperatures. People with different body types also have different amounts of brown fat. For example, overweight or obese individuals have less brown fat than those with a lean body type.
How Does Brown Fat Improve Metabolism?
Brown Fat Burns Extra Calories to Generate Heat
Metabolism involves how you use energy to maintain normal body functions. It involves the chemical reactions that break down the food we consume into sugars and fats and then use them for survival. In addition to converting nutrients and supplying energy, the body can also use the chemical products of metabolism to build new cell structures.
So how does metabolism relate to the body’s ability to generate heat?
Body heat is a by-product of metabolism. The body transforms stored energy into heat through a chemical reaction involving food constituents like carbohydrates, fat, or proteins. Brown fat acts as a “booster” in the metabolic process by helping the body burn extra energy to generate more heat and maintain body temperature.
Being able to burn extra calories is beneficial for those who want to speed up their metabolism and lose weight. However, weight loss occurs when the “calories-out” is higher than the “calories-in.” A “sluggish” metabolism burns fewer calories, meaning more fat is stored in the body. In contrast, a fast metabolism burns calories at a quicker rate.
Brown Fat Contains More Mitochondria for Metabolism
Brown fat cells also contain more mitochondria than white fat. This large number of mitochondria is essential because mitochondria play a vital role in energy metabolism, allowing for enhanced metabolic processes. For example, the mitochondria generate extra ATP to power up our cells by utilizing more energy from our food.
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What Are the Benefits of Improved Metabolism?
Increase Energy Expenditure
When the metabolism increases due to brown fat, the body requires more energy to maintain body functions at rest and during physical activity, causing the body to use more glucose from the bloodstream.
This increased energy expenditure leads to several positive outcomes, including decreases in:
- Blood glucose
- Cholesterol
- Blood pressure
Help Manage Weight-related Diseases
By reducing the critical parameters above, scientists have extrapolated brown fat’s benefits from burning calories to weight loss for treating and managing weight-related diseases.
A body of research is looking into the possibility of targeting brown fat and the browning of white fat as a potential approach to treating obesity. Although more studies are required, understanding the specific mechanisms of brown fat will lay the groundwork for developing a safe and efficient treatment option for obesity and related metabolic disorders.
Surprisingly, other research has shown that obese people with more active brown fat may have better metabolic health than those whose brown fat is inactive.
Specifically, cold-activated thermogenesis (heat production in the human body) was higher in obese people with detectable brown fat than in those without brown fat. As a result, individuals with obesity and active brown fat had lower visceral fat mass (28.8 percent) than those who did not have detectable brown fat.
So how does lower visceral fat relate to better metabolic health?
Lower visceral fat mass was associated with lower insulin resistance, a common hallmark of diabetes, systemic inflammation, and improved nonalcoholic fatty liver disease symptoms.
How to Increase Brown Fat
Brown fat can induce weight loss and other health benefits due to its ability to enhance metabolism. So, how can we activate brown fat cells to lose weight?
Cryotherapy and Cold-water Immersion
Cryotherapy and cold-water immersion are the two emerging approaches to increasing the amount and activity of brown fat in the body.
These procedures involve quickly exposing the body to cold temperatures (as cold as -289°F or -178°C in cryotherapy) to activate the conversion of white fat into brown fat, or the browning of fat.
The human body releases a hormone called norepinephrine when exposed to cold temperatures. Brown fat can be “switched on” in response to norepinephrine and signal the mitochondria to start generating energy. This cascade of effects creates the heat that helps you maintain your body temperature.
Research on human fat and metabolism shows a 42-percent increase in brown fat volume and a 10-percent increase in fat metabolic activity after a month of exposure to mild cold. Furthermore, increasing brown fat during cold exposure may improve insulin sensitivity after eating and change metabolic hormones such as leptin.
Exercise
It has been demonstrated that exercise can increase the amount and activity of brown fat by inducing fat browning through various mechanisms.
Research shows that one of the mechanisms may include the activation of the sympathetic nervous system, a division of the nervous system. Other research, including 56 participants following a moderate-intensity exercise regime, found a consistent increase in a lipid-controlling hormone that can be seen in cold exposure.
The scientists confirmed this connection between exercise and brown fat in a study on animals, where there was no sign of an exercise-induced increase in the lipid-controlling hormone in the absence of brown fat. This finding suggests that brown fat is the source of the lipid-controlling hormone found in the aforementioned human study.
However, a complete understanding of the relationship between exercise and brown fat has yet to be established. Therefore, further research is necessary to determine the type of exercise, the time duration, and the intensity needed to induce the activation of brown fat.
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Diet
A “bad” diet with too many calories may result in poor body composition and excess body fat. A “good” diet, on the other hand, may do the opposite thing: helping the body burn more calories by increasing brown fat. So the question is: what foods increase brown fat?
A review published by Frontiers looked at the effects of different foods on thermogenesis. This initial process activates brown fat.
The review discovered that turmeric and curcumin, foods containing resveratrol, green tea, fish-derived omega-3 fatty acids, and spicy foods containing capsaicin might activate thermogenesis and trigger the browning of white fat. In addition, caffeine may also cause fat browning in humans, according to another review published by Frontiers.
Nevertheless, more research is needed to confirm the effectiveness of those ingredients on brown fat in humans, mainly because the dosages required for some of them, such as resveratrol, may be unrealistically high.
Recent Findings in Brown Fat and Metabolism
Brown Fat Varies in Quantity With Individuals
A study on brown fat mass and activity in 31 lean and 64 obese people found that active brown fat was present in a significantly higher proportion in lean people than in obese people (58 vs. 33 percent).
These figures mean that although obese people have more body fat, the amount of their active brown fat is lower than those with lean body composition. However, despite having a lower prevalence of brown fat, its metabolic activity and heat-producing capacity appear intact in obesity.
Brown Fat Activation as a Treatment of Cancer
A study on rodents showed that brown fat activation due to exposure to cold inhibits the growth of some tumors, including untreatable cancers like pancreatic cancer.
Cold-induced brown fat activation, in particular, hinders metabolism in cancer cells. In contrast, brown fat removal under cold exposure restores tumor growth. These findings offer a paradigm for cancer treatment that is both simple and effective.
Cold exposure and activation of brown fat via any other method, such as drugs and other anticancer therapeutics, are expected to provide a general approach to treating various cancers effectively.
Bottom Line: Brown Fat May Hold the Key to Obesity-related Metabolic Health
Differences in fat type and distribution may help explain the favorable metabolic status. As previously stated, individuals with more active brown fat had a lower proportion of abdominal and visceral fat, which is associated with a lower risk of metabolic diseases. Therefore, scientists are working to develop drug treatments that can activate brown fat.
In conclusion, brown fat plays a crucial role in energy metabolism, heat production, weight loss, and other health conditions. However, the human body progressively loses brown fat with age. Thus, while scientists continue to investigate the mechanisms of brown fat, we must maintain an active lifestyle for optimal body composition.
References
Torgan, C. (2014). Cool Temperature Alters Human Fat and Metabolism. National Institutes of Health.
Sanchez-Delgado, G., Martinez-Tellez, B., Olza, J., Aguilera, C.M., Gil, A., Ruiz J.R. (2015). Role of Exercise in the Activation of Brown Adipose Tissue. Annals of Nutrition and Metabolism. Karger Medical and Scientific Publishers.
Kim, S., Plutzky, J. (2016). Brown Fat and Browning for the Treatment of Obesity and Related Metabolic Disorders. Diabetes & Metabolism Journal.
Stanford, K., Lynes, M., Takahashi, H., Tseng, Y., Coen, P. (2018). 12,13-diHOME: An Exercise-Induced Lipokine that Increases Skeletal Muscle Fatty Acid Uptake. Cell Metabolism Research Journal.
El Hadi, H., Di Vincenzo, A., Vettor, R., Rossato, M. (2019). Food Ingredients Involved in White-to-Brown Adipose Tissue Conversion and in Calorie Burning. Frontiers.
Wein, H. (2019). How Brown Fat Improves Metabolism. National Institutes of Health.
Hensrud, D. (2020). What is Brown Fat? How Is It Different From Other Body Fat? Mayo Clinic.
Herz, C., Kulterer, O., Prager, M., Schmöltzer, C., Langer, F. et al. (2021). Active Brown Adipose Tissue Is Associated With a Healthier Metabolic Phenotype in Obesity. American Diabetes Association.
Van Schaik, L., Kettle, C., Green, R., Irving, H., Rathner, J. (2021). Effects of Caffeine on Brown Adipose Tissue Thermogenesis and Metabolic Homeostasis: A Review. Frontiers.
Henderson, E. (2021). Brown Fat Could Be the Key to Healthy Metabolism in Obese People. News Medical.
Zelman, K. (2022). Brown Fat: What You Need to Know. WebMD Publisher.
Kulterer, O., Herz, C., Prager, M., Schmöltzer, C., Langer, F. et al. (2022). Brown Adipose Tissue Prevalence Is Lower in Obesity but Its Metabolic Activity Is Intact. Frontiers.
Seki, T., Yang, Y., Sun, X., Lim, S., Xie, S. et al. (2022). Brown-fat-mediated Tumor Suppression by Cold-altered Global Metabolism. Nature Research Journal.
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