Sun, 14 April 2019
Just when you thought you knew all the reasons why exercise is good for you, a new scientific discovery gives us yet another one. Today on Spartan Health we’re going to talk about something called “brown fat” or “good fat.”
Recent research has found some possible explanations for why a substance called “brown fat” can actually increase your metabolism. Its beneficial qualities have motivated some people to call it “good fat.”
But before we get too deep in the scientific weeds, let’s make a distinction between brown fat and it’s far better-known cousin, white fat.
White fat is the fat most people think of when they’re focused on losing weight and is used mainly for energy storage in the body. It’s also an efficient insulator and helps to prevent the body from losing heat.
Now to “Brown fat.” Its color is different from white fat because it contains a large number of mitochondria (energy structures in your cells that have high iron levels). This type of fat can actually produce heat on its own by a process called “non-shivering thermogenesis.” Not surprisingly, it’s particularly prevalent in human babies and hibernating animals – which both need to produce heat without exercise.
Until recently, it was thought that brown fat was pretty much a non-factor in adult human health; however, the latest research has shown a more important role of brown fat than was previously understood (because it does make up a small amount of all adult fat stores).
So what’s the magic of brown fat during exercise? Contrary to what people might think, exercise does not activate brown fat to somehow burn calories or to take up energy that comes from fat or carbohydrates.
Instead of burning up calories itself, brown fat increases metabolism by becoming a signaling device to the muscles; it actually triggers a muscle to take up more fatty acids to use as fuel. Brown fat is part of an array or group of metabolic tissues that communicate with one another and enable muscles to perform their functions during exercise.
This signaling from brown fat is also what happens during cold exposure where it can help produce heat. But now, we know that brown fat is also useful in its role in raising the body’s metabolism.
So we know that exercise may burn your white fat, but, at the same time, it helps brown fat regulate the functioning of your muscles during exercise – especially how to use (and burn up) energy. Pretty cool stuff.
KEY TERMS & IDEAS
Brown fat’s importance in the consumption of calories in adults has only recently been recognized. Its main importance lies in its function as a conduit of communication with a network of cells that “tell” muscles to take up fatty acids as fuel.
White fat. Unlike brown fat, white fat have far fewer mitochondria and blood vessels than brown fat and is made up of just one substance (a lipid droplet) that is clearer than brown fat – thus having a “white” appearance. It’s involved in storing energy for the body as well as insulation.
Brown fat: A fat that gets its coloration from many iron-rich mitochondria in it. It’s involved in helping to create heat without movement in the body, which is needed for hibernating animals and human babies.
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Misti Crane, “Study links ‘good’ brown fat and exercise,” Medical Press, May 1, 2018, https://medicalxpress.com/news/2018-05-links-good-brown-fat.html, accessed January 2019.
Patrick Seale and Mitchell A. Lazar, "Brown fat in humans: turning up the heat on obesity," Diabetes 58.7 (2009): 1482-1484, http://diabetes.diabetesjournals.org/content/diabetes/58/7/1482.full.pdf.
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