When most people think about fat, they tend to imagine it as a single, homogeneous substance. Most people also envision their body fat to be yellow blobs. I know I did for a long time when I saw a video of a personal trainer throw a bumpy yellow rubber mold (made to look like fat, I guess) on a table while yelling to a woman: “IS THIS WHAT YOU WANT? HUH, HUH? YOU WANT THIS FOR YOUR LIFE?”
The clearly intimidated and humiliated woman picked up the yellow rubbery “fat” and started crying, violently shaking her head no. I remember thinking two things: “Wow, this guy’s tactic is horrifying,” and two, “Why would he choose yellow? What a putz.”
So, by now you might be thinking, “Well, what color is fat, Jen?” The truth: Fat isn’t just one color or one type. In fact, there are two distinct types of fat tissue in the human body: brown fat and white fat. These two types of fat serve different functions, have different appearances and affect your health in diverse ways. The question is, what color is your fat, and how does it influence your body?
White fat: the energy reserve
White fat, also known as white adipose tissue (WAT), is what most people traditionally think of as body fat. This type of fat stores energy in the form of large, oily droplets that expand or shrink depending on your diet and activity levels. White fat also plays a role in cushioning vital organs, providing insulation to maintain body temperature and producing hormones like leptin, which regulate hunger and metabolism.
However, too much white fat, particularly around the abdomen, is linked to various health issues. Excessive white fat can increase the risk of heart disease, type 2 diabetes and other metabolic disorders. While white fat is essential for survival, its accumulation can become problematic if not kept in check through diet and exercise.
Brown fat: the calorie burner
Brown fat, or brown adipose tissue (BAT), is a completely different type of fat. Instead of storing energy, it burns calories to generate heat – a process known as thermogenesis. Brown fat contains a high number of mitochondria, the energy-producing components of cells, which give it its characteristic brown color. The primary function of brown fat is to help regulate body temperature, especially in newborns and animals that hibernate.
Unlike white fat, brown fat is metabolically active and can help improve insulin sensitivity and reduce the risk of obesity. While adults have significantly less brown fat than newborns, researchers have found that we still retain some brown fat stores, typically around the neck, shoulders and spine. The good news is that it’s possible to increase your brown fat levels, which could have a beneficial impact on your overall metabolism.
How brown fat and white fat differ
One of the key differences between brown and white fat is their function. Brown fat is an active player in calorie burning, whereas white fat is more passive.
Another significant difference is where these fats are located. White fat is commonly found throughout the body, particularly in the abdomen, thighs and buttocks. Brown fat is typically located in smaller, concentrated areas like the upper back, neck and shoulders.
In terms of health, having more white fat — especially visceral fat, which surrounds organs — can increase the risk of various diseases. Brown fat, in contrast, has been linked to improved metabolic health and may help protect against conditions like obesity and diabetes.
Converting white fat to brown fat: Is it possible?
Recent studies suggest that it is possible to convert white fat into brown-like fat, often referred to as “beige” fat. This beige fat behaves more like brown fat, meaning it burns calories rather than storing them. So, how can you encourage this transformation?
- Cold exposure: One of the most well-known ways to activate brown fat and encourage the conversion of white fat into brown fat is through cold exposure. When you’re cold, your body burns more energy to generate heat, which increases brown fat activity. Taking cold showers, using cold plunges (more on this in an upcoming article) or spending time in cold environments can help stimulate this process. Studies have shown that people who are regularly exposed to colder temperatures tend to have more active brown fat.
- Exercise: Physical activity is another way to promote the browning of white fat. Exercise releases a hormone called irisin, which is thought to trigger the conversion of white fat cells into brown-like fat. Regular exercise also increases overall energy expenditure, which helps reduce white fat stores.
- Certain foods: Some studies have found that certain foods and nutrients can also help activate brown fat. Capsaicin, the compound that gives chili peppers their heat, has been shown to stimulate brown fat activity. Green tea, rich in catechins, and resveratrol, a compound found in red wine and berries, may also enhance the browning of white fat. Now, don’t go down the red wine hole and think drinking multiple glasses throughout the day is going to be your new “diet plan.” First, not all red wines are created equal, and as much as I love what resveratrol can do, the alcohol content often offsets the benefits if you don’t keep it to one glass two or three times per week. Berries are a MUCH better option.
- Quality sleep: Sleep affects various hormones that regulate fat metabolism. Poor sleep disrupts the balance of these hormones, potentially leading to increased white fat accumulation. On the other hand, good quality sleep helps maintain a healthy metabolism, which can support the activation of brown fat.
So, what color is your fat? There are several high-tech ways to measure how much WAT vs BAT a person has. A PET-CT scan is the gold standard, but there are other tests including a DXA scan, thermal imaging, biomarkers found in blood work as well as hormone levels, and biopsies. I encourage you to talk to your primary care provider to see what is available to you. The good news is that you can throw that rubber yellow “fat” back in that jerk’s face, say “I’d like to start converting white fat into brown,” and walk out the door with your head held high, because you are in control and you can make big changes.
