What Is Brown Fat and Why Is It Important?
When we hear the word “fat,” we usually think of something negative, something to avoid at all costs. But, as with most things in life, it’s not that simple. Fat plays essential roles in the body: it stores energy, protects organs, and regulates temperature.
Fun fact: Nearly 60% of the human brain is made of fat. Why? Because fat insulates electricity—and the brain, packed with neurons communicating through electrical impulses, needs that insulation to prevent overheating.
Our bodies have two main types of fat:
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White fat: Accumulates in areas like the abdomen and thighs. It’s the type commonly associated with weight gain. It’s relatively passive and mainly stores energy.
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Brown fat: Found mostly in the neck, shoulders, and upper back. It’s metabolically active and burns calories by increasing energy expenditure when activated.
What makes brown fat especially important is its ability to stimulate the growth of mitochondria within cells.
Dr. Florencia Leinado describes a mitochondrion as a “small engine” that converts glucose and fats into ATP (energy). Almost all cells contain mitochondria, and every bodily function depends on them to sustain life.
For overall health—and especially for healthy longevity—having mitochondria that are both abundant and functioning properly is essential.
How to Activate Brown Fat with Ice Baths
According to Susanna Søberg, PhD, when something is critical for our survival and evolution, the body builds multiple systems to support it. Brown fat evolved to regulate body temperature, helping us stay alive and avoid hypothermia.
There are three main pathways for activating brown fat:
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Cold receptors → hypothalamus → neurotransmitters → brown fat
When we immerse ourselves in cold water, cold receptors in the skin send signals to the hypothalamus, the brain’s temperature-regulating center. This triggers a rapid increase in neurotransmitters. One of them, norepinephrine, directly activates brown fat. -
Cold receptors → brown fat (direct activation)
As skin temperature drops, brown fat responds by generating heat. -
Muscle shivering → brown fat
When body temperature falls, we begin to shiver. These small muscle contractions activate brown fat as well.
What are the benefits of activating brown fat?
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Increases calorie expenditure
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Improves insulin sensitivity
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Promotes loss of white fat
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Stimulates mitochondrial production
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Enhances thermogenesis (heat production)
Søberg explains that cold is the most powerful stressor for activating brown fat because brown fat is the organ responsible for regulating body temperature.
Shivering, Metabolism, and Cellular Health
There’s no need to fear shivering. It’s a form of positive stress, also known as hormesis. As long as we don’t enter hypothermia, this type of stress strengthens our cells, boosts metabolism, and supports overall health.
“Shivering is training. It’s training for your muscles, for your metabolism. You’re strengthening your cells,” Søberg explains.
The more we expose our cells to this kind of stress—through cold exposure or exercise—the better they become at keeping us healthy.
So: no fear of success.
If you enjoyed this article and want to learn more about cryotherapy and its benefits, we invite you to explore our Wellness Journal. And if you’re ready to take it a step further, discover the Ice Baths from Alfa Humans.
*Alfa Humans is designed to support a healthy lifestyle, not to diagnose, treat, cure, or prevent any disease or medical condition. Our tubs are not medical devices. Please consult your physician before engaging in deliberate cold exposure practices.
