What is brown fat and how does it increase metabolism?

Recently, everyone's been talking about brown fat and the role it plays when it comes to supporting metabolism and aiding weight management.

"It's a good fat!" you'll hear people say, but is there such a thing? Can brown fat cells really help combat obesity and help you lose weight, or is this just the latest fad we'll forget about next month? And while we're at it, what's the difference between brown and white fat, anyway?

In this article, we'll break down everything you need to know about brown fat and what the latest research findings suggest when it comes to how brown fat can support weight management.

What is brown fat?

Brown fat — also known as brown adipose tissue — is a special type of fat that plays a key role when it comes to both producing heat and burning energy [1]. Unlike white fat, which stores energy, brown fat breaks down fat molecules to create heat. This is because brown fat cells are packed with mitochondria — the tiny powerhouses in our cells — that actively burn energy to keep us warm. In turn, this helps our bodies maintain body temperature in cold environments [1].

It's a process known as non-shivering thermogenesis, and it’s why brown fat is often referred to as "good fat". While we’re all born with it, the amount of brown fat cells and brown fat activity can vary widely between people.

Brown fat vs white fat

Brown fat and white fat serve very different purposes in the body. White fat, or white adipose tissue, is the more common type — it's the fat we typically think of when we talk about body fat [1]. White fat molecules store extra energy and build up as fatty tissue when we consume more calories than we burn. But having too much white fat can lead to weight gain, and in turn, this can cause health issues like insulin resistance.

In contrast, brown adipose tissue — which is packed with iron-rich mitochondria — burns calories and produces heat. Where white fat stores energy, brown fat uses it. This is why brown fat cells are dark in colour and metabolically active, but having too much white fat is associated with increased risk of heart disease, kidney disease, and other chronic conditions. On the flip side, brown adipose tissue acts as a built-in calorie-burning system, which has made it a hot topic in medical research that's focused on how to combat obesity.

What does brown fat do?

Essentially, brown fat acts like your body’s natural furnace, helping you stay warm and potentially supporting metabolic health [1]. Brown fat works its magic through a process called thermogenesis, which is where brown fat cells convert fat molecules and amino acids into heat [2]. This helps your body temperature stay warm when you're out in cold temperatures, and helps your body burn calories — even at rest — because it's converting those calories as a way to keep you from turning into one big shivering muscle, basically [3].

In fact, studies have shown that active brown adipose tissue breaks down fat stores and helps regulate blood sugar levels and body weight [1][3]. But while we all have some brown fat, it’s typically more active in lean individuals and tends to decrease with age.

While you can’t rely on it alone to lose weight, it may offer a helpful metabolic boost when combined with other healthy lifestyle habits.

Why is brown fat the colour brown?

Brown fat gets its distinctive colour from the high concentration of mitochondria, which are tiny structures within cells that produce energy and work to maintain body temperature [1]. These mitochondria contain iron, which is how brown fat has that darker, reddish-brown hue.

In contrast, white fat tissue has far fewer mitochondria and larger fat droplets, making it appear pale or yellowish. The iron-rich mitochondria in brown fat are also what make it so metabolically active, allowing it to burn calories and generate heat. So, that brownish colour isn’t just cosmetic — it’s a sign that this type of fat is working hard behind the scenes to support your metabolism and keep you warm.

How much brown fat is in my body?

The amount of brown fat in your body is dependent on a number of factors, and can vary based on your age, body composition, genetics, and even the climate you live in.

Interestingly, people who are lean, younger, or exposed to colder temperatures tend to have more active brown fat, but most adults only have small amounts of brown adipose tissue.  Typically, adults will have a small amount of brown fat cells, which are concentrated in areas like the neck, kidneys, adrenal glands, heart and chest [1]. Still, brown fat is incredibly efficient: just a few ounces can burn a surprising number of calories when activated.

How can I increase brown fat in my body?

While there's no magic trick to boosting the amount of brown fat in your body, there are certain lifestyle habits that can help to activate the brown fat cells you already have, and over time, this can potentially increase the amount of brown fat  you have.

Regularly spending time in cold temperatures can help activate brown fat cells, as it will force them to create heat in order to maintain your body's temperature [1][3]. Some ways you can do this would be by taking cold showers or going for brisk walks when it's chilly outside.

Exercise may also help, as it’s been shown to trigger the release of a hormone called irisin, which may encourage white fat cells to behave more like brown fat — a process known as “browning” [2]. Eating a healthy diet rich in whole foods, getting quality sleep, and managing stress can also support a healthier metabolism overall, which may indirectly support brown fat function. While more research is needed, these science-backed habits offer promising ways to tap into your body’s natural fat-burning potential.

What foods produce brown fat?

While there aren't any foods that directly create brown fat, there are some ingredients that can help activate it or support the process of “browning,” where white fat cells start to act more like brown fat. Capsaicin, which is found in chilli peppers, curcumin (from turmeric), and catechins (especially in green tea) have all been linked to increased brown fat activity [4].

Outside of this, it's important to consider the type of fat you're including in your diet. Increasing healthy fats — like the type found in avocados, nuts and fish[1,4] — can help to support metabolic health. In turn, this can help your body use its fat more efficiently.

And don’t forget protein, which has a high thermic effect. This means your body burns more calories digesting it, which may complement brown fat’s calorie-burning role. While these foods won’t magically create brown fat, they can be part of a balanced, metabolism-friendly diet that supports your body’s natural energy-burning processes.

Does coffee increase brown fat?

Yes, new research suggests that coffee might help stimulate brown fat activity [5]. Caffeine consumption — specifically from a cup of coffee — appeared to activate brown fat in participants.

The theory is that caffeine stimulates the nervous system, which in turn promotes heat production (via thermogenesis) in brown fat. This could mean your morning brew is doing more than just waking you up — it might also be giving your metabolism a subtle boost. That said, the research is still early, and it’s not a reason to overdo it on caffeine. But in moderation, your daily coffee habit could be supporting brown fat activation as part of a broader, healthy lifestyle.

How do I know if I have brown fat or white fat?

All adult humans have both brown and white fat in their bodies, and unfortunately, you can’t tell which is which just by looking in the mirror. White fat builds in areas like the belly, thighs, and hips and is what stores energy, but when it comes to weight gain, it's also storing excess calories. Brown fat, on the other hand, is found in smaller amounts and hidden deeper in the body.

The only way to definitively measure brown fat is through specialised imaging tests, like PET-CT scans, which are typically done in research settings [6]. But there are some clues that your brown fat might be more active: for example, if you tend to feel warm easily in cold environments or have a faster metabolism despite a lower body weight.

Still, most of us don’t need to measure brown fat to benefit from it — healthy habits like regular exercise, cold exposure, and a balanced diet can help keep both types of fat working in your favour.

Brown fat and weight loss

Brown fat has become very buzzy in the weight loss space recently, and it's easy to see why. Unlike white fat, which stores energy and can lead to weight gain, brown fat burns it with a heat production process called thermogenesis [2]. That means the more active your brown fat is, the more calories your body can burn, even when you're not up and about.

While most people have only small amounts of brown fat, activating it through cold exposure, exercise, and dietary choices may help support your weight loss efforts by boosting your metabolism naturally.

However, having more or less brown fat isn't the magic key to weight loss, and that's where Juniper comes in.

Juniper's Weight Loss Reset Programme combines weight loss medication with dietitian-led health coaching and tracking, so you can lose weight and reach your goals for good.

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Plus, we have a team of expert dietitians and health coaches you can consult with to help you work through any challenges you're experiencing during your weight management journey. This approach sets you up for sustained weight loss, rather than a quick-fix solution.

This means you can continue to enjoy the things you love in moderation without ever feeling deprived.

Ready to see if Juniper is right for you? You can check your eligibility here.

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