Not all fat is created equally, and within our bodies there are three types of fat: brown fat (brown adipose tissue), white fat (white adipose tissue) and beige fat (beige adipose tissue).
Brown fat is a type of body fat that breaks down blood sugar and fat to generate body heat and maintain body temperature.
White adipose tissue, the most common kind of fat in our bodies, stores extra energy that can be used when you don’t consume enough calories.
Beige fat shares characteristics of both brown and white fat. It can generate heat like brown fat and burn energy for calories like white fat.
The process of activating brown fat has researchers excited about the potential brown fat health benefits. Read on to learn about brown fat and its role in metabolic disorders, heart health, weight management and Type 2 diabetes.
What Is Brown Fat?
Brown fat is metabolically active and burns calories to generate heat in cold conditions. Specifically, brown fat is in charge of thermogenesis, the process which regulates body temperature, especially in response to cold. Brown fat activates in cold temperatures right before you start to shiver to help keep you warm. Our ancestors might have developed brown fat to help survive hypothermia.
Humans have varying levels of brown fat. Newborn babies have very little total body fat. But about 2% to 5% of a baby’s total body weight is brown fat.
“Infants have the highest amounts of brown fat because they are so small and hairless, from there it goes down as we age with each decade from our 20s,” says Dr. Paul Cohen, a senior attending physician, the Albert Resnick MD Associate Professor and head of the Laboratory of Molecular Metabolism at The Rockefeller University in New York City. Brown fat is primarily located in the neck, around the shoulder blades and kidneys, adrenal glands, heart, chest and along the spinal cord of adults.
The brown color of the fat cells is due to the mitochondria, the powerhouse of the cell that is also responsible for burning energy as heat. Mitochondria are rich in iron, which gives brown fat its color.
“Brown fat has the ability to convert fat calories into heat,” explains Cohen. “The process of generating heat burns calories and also acts like a waste basket, clearing unhealthy metabolites from blood.” Excess metabolites contribute to heart disease, insulin resistance and diabetes.
[READ: Guide to Boosting Your Metabolism.]
Brown Fat vs. White Fat
Simply put, white fat stores energy, brown fat burns it.
Brown fat is much less common than white fat. Most of the fat in an adult body is white fat.
“Every person is different and there are challenges measuring the precise amount of different fats in the body, but in general, a healthy 154-pound adult may have 15% to 20% (23 to 31 pounds) or more of white fat and only 100 to 200 grams (less than one cup) of brown fat,” says Cohen.
Brown fat’s primary role is to help maintain body temperature. It achieves heat production by breaking down blood sugar and fats.
White fat, on the other hand, serves to store energy in the form of fat and burn it during calorie deficits. White fat is the primary storage form of triglycerides, which the body calls upon for energy when needed.
The droplets of white fat are large compared to the tiny droplets of brown fat. White fat is also involved in endocrine functions, metabolism and appetite regulation.
The majority of adults in the U.S. carry too much white fat, which also increases risk for Type 2 diabetes, obesity and other diseases.
Health Benefits of Brown Fat
Brown fat is a hot topic of research. Scientists are seeking ways to increase activation of existing brown fat in order to harness its calorie-burning power and promote metabolic health, weight loss and heart health.
Brown fat may play a role in treating obesity, insulin resistance, enhance the body’s ability to regulate blood sugar and promote healthy cholesterol levels. It has long been speculated that activating brown fat may be useful in treating obesity and related metabolic conditions.
“Think of brown fat as a furnace that uses glucose for fuel thereby using glucose could improve insulin resistance, reduce glucose levels and promote health benefits,” says Cohen. “We know that brown fat is associated with glucose lowering, anti-diabetes effects and cardiovascular conditions but we don’t know what is responsible for these benefits and how we can leverage them to improve human health.”
Cohen goes on to add, however, that “activating brown fat might not necessarily result in weight loss as it is only one of the many variables that affect weight including environment, medical history, medication use, activity level and dietary patterns.”
[READ: Which Diet Is Best? Plant-Based, Low-Fat vs. Animal-Based, Low-Carb]
Brown Fat Activation
The principal way to increase brown fat activation is through cold exposure. When the body is exposed to cold temperatures, brown fat is activated to generate heat and help maintain body temperature.
“The amount of brown fat doesn’t really change but it becomes more active,” says Cohen.
Cold exposure
A 2022 meta-analysis of 10 research papers over the past 30 years revealed that acute cold exposure could improve energy expenditure and brown fat activity in adults. Taking cold showers, sitting in an ice bath, taking a plunge in cold water, turning down the thermostat in your home or stepping outside on a cold day are strategies that have been proposed to stimulate brown fat activation.
One very small study found that men exposed to mild cold each night for a month had a 42% increase in brown fat volume and a 10% increase in fat metabolic activity.
“The exact temperature and exposure time needed for health benefits have not been determined,” says Emma Laing, spokesperson for the Academy of Nutrition and Dietetics and University of Georgia professor.
Food
Dietary components such as caffeine, ursolic acid in apples, ginseng, turmeric, foods with resveratrol (such as grapes and raspberries), catechin in green teas, kudzu flower oil and others have been studied, mostly in animal models, but with only preliminary evidence. Since brown fat is rich in iron, eating iron-rich food could support brown fat activation as well.
“Without more concrete evidence in humans that diet can activate brown fat, and to what degree, it is difficult to make nutrition recommendations specific to this process,” says Laing.
Exercise
Exercise is another area of research that has been studied to determine its relationship to brown fat. However, results are mixed. Some human and animal studies contradict each other.
Some research suggests that exercise activates your body’s blood hormone irisin, which then signals white fat in your body to burn like brown or beige fat, a processing known as “browning.”
One study of aged mice indicated an improvement in the mitochondrial function in brown fat by exercise and showed improvement in both cardiac and metabolic health.
Another study showed combined exercise training induced activation of brown and beige fat and displayed metabolic and cardiovascular benefits.
Regardless of its role with brown fat, regular exercise is beneficial and can combat age-related diseases and improve both cardiac and metabolic health.
Medications
Some evidence suggests that popular weight loss medications known as glucagon-like peptide-1 (Ozempic, Wegovy) may increase brown fat activity.
A small study looked at a drug to treat overactive bladder and found it boosted brown fat activation while also improving glucose metabolism, HDL cholesterol and insulin sensitivity in healthy women. The results suggest the potential benefit of brown fat in treating metabolic diseases.
How to Increase Brown Fat
Genetics, environment, age, gender, body composition and physical activity affect the amount of brown fat in the body. It is more common in women than men, and it also decreases with higher body mass index.
“Scientists have found that some individuals have a greater quantity of brown fat in the body than others, and that some people have a higher brown fat activity level at room temperature than others,” says Laing
It is generally understood that the quantity of brown fat in an adult cannot be increased. It naturally decreases with each decade as a part of aging.
Researchers are trying to understand why the body reduces brown fat during aging so they could potentially block the process and maintain higher levels.
One way to partially increase brown fat is by changing white fat into beige fat through exercise. Both cold exposure and exercise can stimulate browning, the conversion of white fat into brown/beige fat. Athletes, according to the Cleveland Clinic, have more brown fat than others.
According to Laing, other mechanisms to harness brown fat that have been proposed include obtaining adequate sleep, regular exercise and eating a well-rounded diet.
Tests to check brown fat levels
The gold standard to evaluate brown fat levels is a positron emission tomography (PET) scan and a computed tomography (CT) scan. The PET scan is an imaging test that can help reveal the metabolic function of your tissues. A CT scan creates an image of organs, bones and tissues. An additional test showing promise is the magnetic resonance imaging (MRI), which can form pictures of the body.
Are there supplements to increase brown fat?
Unfortunately, there are no supplements that are known to activate or increase brown fat.
“Herbal compounds such as ginseng, quercetin and olive leaf extract are also of interest to scientists, but there are no dietary supplements that have been proven to activate BAT (brown adipose tissue) in humans, but research is ongoing,” reports Laing.
Bottom Line
Brown fat is a metabolically active tissue that regulates body temperature and energy expenditure. It maintains body temperature, produces and stores energy, burns calories and helps control metabolites, blood sugar and insulin levels. The potential benefits of brown fat are intriguing yet the full extent of its impact on health are still being explored.
Brown fat research is a very young field, with discovery only about 15 years ago. While more research is needed to fully understand its therapeutic potential, brown fat has captured significant attention for its potential implications in metabolic health and weight regulation.
While research continues to reveal benefits of brown fat, there is little harm in harnessing the known lifestyle strategies that can improve health such as regular physical activity, healthy dietary patterns and regular sleep. This time of year, why not increase your exposure to cold temperatures to help activate your brown fat?
More from U.S. News
10 Bedtime Foods & Drinks for Deep Sleep
Best High-Protein Foods: Meals, Snacks and Desserts
10 Best Electrolyte Drinks: Hydration Options for Optimal Health
What Is Brown Fat And How Can It Improve Metabolism? originally appeared on usnews.com
