When I first learned that we have different “colors” of fat, I immediately wondered: Can we find out how much of each type we have? If white fat stores energy and brown fat burns it, wouldn’t it be nice to know where we stand?
Unfortunately, science isn’t quite there yet.
The truth is that there is no routine test your doctor can order to tell you how much white, brown, or beige fat you have. There isn’t a blood test, body composition scale, DEXA scan, or office measurement that can tell us the percentage of each type of fat in your body.
Researchers can study these fat types, but doing so requires highly specialized imaging or even tissue biopsies. That’s great for scientific studies, but it isn’t something we use in everyday medical practice.
A Quick Refresher on the Three Types of Fat
White fat is what most people think of when they think about body fat. It stores energy, cushions organs, produces hormones, and makes up the majority of the fat in our bodies.
Brown fat is different. It contains large numbers of mitochondria, the tiny power plants inside our cells. Rather than storing calories, brown fat can burn them to produce heat.
Beige fat is somewhere in between. These cells develop within white fat tissue and can behave more like brown fat under certain conditions.
Think of beige fat as the body’s “hybrid vehicle.” It can act more like a storage cell or more like a calorie-burning cell depending on the signals it receives.
Why Can’t We Measure It?
The difference between white, brown, and beige fat happens at the cellular level.
You can’t feel it. You can’t see it in the mirror. Your provider can’t determine it during an examination.
Under a microscope, these cells look very different. White fat cells are mostly one large droplet of stored fat. Brown fat cells contain many smaller lipid droplets and are packed with mitochondria. Beige fat cells share characteristics of both.
The challenge is that beige and brown fat overlap so much that even advanced imaging technologies struggle to tell them apart.
In many studies, what researchers call “brown fat” is actually a mixture of both brown and beige fat cells.
What Do Researchers Use?
The gold standard is a special PET/CT scan performed after cold exposure.
Researchers expose participants to a cool environment and then use imaging to identify areas that become metabolically active. This can help estimate the activity of thermogenic fat, but it only shows fat that is actively burning fuel at that moment.
Even then, the scan cannot reliably distinguish brown fat from beige fat.
Researchers may also use advanced MRI techniques, infrared thermography, or tissue biopsies, but these remain research tools rather than routine clinical tests.
So if you’ve ever wondered whether your annual physical can tell you how much brown fat you have, the answer is no.
Does Weight Loss Increase Brown Fat?
This is where things get interesting.
Adipose tissue is remarkably adaptable. Scientists call this fat plasticity, meaning that fat tissue can change its behavior over time.
In general, people who are leaner, younger, and more metabolically healthy tend to have more detectable brown fat activity.
However, studies looking at weight loss and fat “browning” have produced mixed results.
Some research suggests that significant weight loss, particularly after bariatric surgery, may increase detectable brown or beige fat activity.
Other studies show that calorie restriction alone does not necessarily increase browning, even when substantial weight loss occurs.
Exercise appears to have its own unique effect. Some studies suggest that regular physical activity can increase brown fat activity without actually increasing the amount of brown fat present.
In other words, your fat may become more metabolically active even if the total quantity doesn’t change.
What Should We Focus On Instead?
This is the part I find most important.
Many patients become fascinated by the latest discussion of brown fat, beige fat, mitochondria, and metabolic flexibility. The science is exciting, but we should not lose sight of what actually matters.
We cannot currently measure the color of your fat in a meaningful clinical way.
What we can measure are the things that directly affect your health:
- Weight
- Waist circumference
- Blood sugar
- Insulin resistance
- Cholesterol
- Blood pressure
- Physical fitness
- Strength and muscle mass
- Optimized Hormone Levels
The good news is that the habits that support healthy brown fat activity are the exact same habits that improve overall health:
- Regular exercise
- Maintaining a healthy weight
- Good sleep
- Stress management
- Occasional cold exposure
- A nutrient-dense diet
We want to help
Science has discovered that fat is far more complex than we once believed. White fat stores energy. Brown fat burns energy. Beige fat lives somewhere in between.
What science has not given us is a practical way to measure exactly how much of each type of fat any individual has.
For now, don’t worry about whether your fat is white, brown, or beige. Focus on the habits that improve metabolic health. If you’re exercising, building muscle, maintaining a healthy weight, sleeping well, and keeping inflammation under control, you’re already doing the things that help your body’s fat cells function the way they were designed to.
And honestly, that’s far more important than knowing their color, come in and we will measure your SECA and discuss what we do know.
