Body Fat: How to Use It and Lose It

A closer look at body fat: Where does it comes from, why do we need it, what are the best ways to burn it off, and where the heck does it go?

Brock Armstrong
7-minute read
Episode #361

body fat measure scale

Body fat, or the more technical term adipocytes (adipo means fat and cyte means cell), is found in many places around the human body and mostly underneath your skin, what we call subcutaneous fat. There is also some on top of your kidneys, inside your liver, and a small amount in your muscle tissue, which we call visceral fat.

An adult male often tends to carry his body fat in his chest, abdomen, and buttocks. An adult female tends to carry her fat in the breasts, hips, waist, and buttocks.

The main role of body fat is to serve as a type of energy storage facility. Up until the mid-nineties, it was thought of strictly as a passive place for us to store energy for the hard times, the times when our ancestors’ hunt didn’t go well (or the weather was poor) and there wasn’t enough food available. This turned out to be incorrect and it does have other uses but it is exceedingly good at storing energy.

A single pound of fat contains roughly 3,500 calories of stored energy.

A single pound of fat contains roughly 3,500 calories of stored energy. Assuming you could burn 100% body fat as fuel, this is enough energy for a 150-pound person to trudge about 35 miles. And that is only one pound of fat and most of us have a lot more than that to spare.

So how does the body use fat and what else is it for? Let’s take a look.

What burns the most energy?

Even though it just sits there, on top of our sinuses, our brain uses about 20 percent of the calories we burn in a day, despite the fact that it only makes up about two percent of the body's total weight. Now, I know what just crossed your mind: Yes, making yourself think harder, or solving a really complicated math problem, does indeed increase the glucose uptake of the brain, but not for very long. So thinking hard is not your best weight loss plan and mathletes may need to do more than math to stay fit. 

Interestingly, the average adult brain consumes about 12 watts of energy in a single day. That is about one-fifth of the power a standard light bulb needs or the same amount of wattage that your iPad uses. So it turns out we have more in common with our devices than we thought.

Your organs, like your heart, lungs, and liver make up five percent of the body's weight but together consume about 50 percent of your daily calories. Now, we know how to give our heart and lungs a good workout but if you can devise a way to exercise your liver, let me know. That is a million dollar exercise craze right there!

We’ve all heard that muscle burns more calories than fat and yes, that is true, but sadly it is not as exciting and impactful as you may think according to a paper on the energy needs of the body.

Your fat tissue burns two calories for every pound of your total body weight and your skeletal muscle burns six calories per pound. Three times as much isn’t anything to sneeze at. Still, relying on your biceps to burn off that extra piece of pie may be a better weight loss strategy than cracking a Sudoku puzzle, but not by much.

But there is some good news. We have more than one kind of fat in our body. We have white fat and brown fat. The primary type of fat cell in our body is called white adipose tissue (WAT), so named because it is a milky yellow. The other type of fat is called brown adipose tissue (BAT) which is actually reddish orange, and turns out to be a lot more interesting than WAT.


About the Author

Brock Armstrong

Brock Armstrong is a certified AFLCA Group Fitness Leader with a designation in Portable Equipment, NCCP and CAC Triathlon Coach, and a TnT certified run coach. He is also on the board of advisors for the Primal Health Coach Institute and a guest faculty member of the Human Potential Institute. Do you have a fitness question? Leave a message on the Get-Fit Guy listener line. Your question could be featured on the show.