How Your Body Burns Fat

There’s one essential aspect that needs to be attained before any sort of fat loss is possible.

Want to know the secret to losing weight? Here it is – create a caloric deficit.


Simply put, a caloric deficit is when you burn more calories than you consume.

Why is the term “deficit” used? - When you take the number of calories you consume and subtract out the number of calories you burn, that number is negative.

So…if you consume 2000 calories and burn 2500, you’ve created a 500-calorie deficit for that day. (2000-2500 = -500) – easy enough!


You body uses calories to create energy for everyday tasks like moving, digesting, even breathing.

When your body isn’t providing all the calories it needs to perform, you’re in a state of negative energy balance. That means you body has to pull energy from somewhere else.

And from where does it pull that energy? You guessed it – from your body fat!


Fat is stored inside the fat cell in the form of triaglycerol. It cannot be burned right there inside of the cell – it has to be released first.

When your body realizes it’s in a state of energy deficit, it sends hormones and enzymes that signal the fat cells to release the fat reserves.

These signal cause hydrolysis (fat breakdown) that splits the molecule, triaglycerol, into glycerol and three fatty acids.

These fatty acids are then released through the bloodstream and travel to the muscles where the energy is needed.

The enzyme lipoprotein lipase (LPL) helps the fatty acids get inside the mitochondria of the muscle cell, where they can be burned for energy.


Every pound of fat contains about 3500 calories. So in order to burn 1 pound per week, you’d need to create a 500-calorie deficit each day.

The best way to achieve a deficit is through a combination of healthy dieting and combination exercise.

Aerobic exercises like walking or jogging tend to burn more overall calories during exercise than strength/resistance workouts. 

However, resistance workouts increase the amount of muscle tissue in your body. Muscle tissue is extremely metabolically active, meaning it uses up a lot of energy (or calories) to maintain its proper function. In addition, the high amount of recovery needed after a workout increases your calorie burn which is why strength training is so effective for fat loss.  

Therefore, increasing your muscle mass helps you burn more calories, even while you’re at rest.

It’s important to note, however, that the more weight you lose, the less energy your body needs to function correctly.

That’s why it’s important you don’t forget the diet aspect - because even with lots of hard training, the greatest energy deficit will come from your nutrition, not your exercise.  While exercise is crucial and can help refine what your body looks like, it is a relatively small calorie expenditure compared to what you can accomplish with some healthy calorie restriction.

Note from Luke:  We have all seen (or experienced ourselves) the phenomena of someone exercising 5,6 or 7 times a week and make ZERO changes to their body fat.  You might see this person exercising their butt off almost every day, for weeks and months and look exactly the same as when they started.  Sure, they may have gotten stronger, more mobile or even increased some health markers like lower resting heart rate.

But sometimes with really poor nutrition you see someone who exercises hard and looks the same and has made little strength improvements too.  So the answer is not "exercise more" because it simply can't be.  They wouldn't recover. What's holding back their fat loss, muscle gain and health is their nutrition.

How can this be?  If you exercise a lot, how could you NOT lose weight?  Like we've discussed above, there HAS to be a calorie deficit.  That's the main driver of your bodyweight. You can argue all you want but it's either alcohol, weekend binges or simply misunderstanding portions leading to you consuming the same or more calories as you're expending. I've had countless clients tell me they "can't" lose weight despite eating healthy and exercising a lot.  The answer is often simple and straightforward: the client simply doesn't understand portion control or underestimates their cheat meals and alcohol.

Creating a smart calorie deficit

While the math of 500 calories per day should lead to a pound of fat loss per week, I prefer to create a deficit based off a percent of someone's calories.


What's a 500 calorie deficit to a large man whose maintenance calories are 3300 per day?  Not a lot.

What's a 500 calorie deficit to a small, post-menopausal woman whose maintenance calories are 1400 per day?  Overkill.

The smart way to create a calorie deficit is to find your maintenance and then subtract 10-20% from there, which will create an excellent fat loss environment that fits your personal calorie needs.  This method avoids the trap many people fall into of eating a lot less at first, losing a bunch of weight and then stalling for the next 6-12 months.  Too much too soon is the enemy of long-term results.  With this method, you can start at 10% deficit and every time you slow, subtract another 5%.  Then only add exercise when you've reached a 20% deficit and this exercise can be as simple as walking more.

How do you ensure you'll keep all your muscle while losing bodyfat?  Stay tuned for our next article on maximizing fat loss while maintaining or even gaining muscle.


"Caloric Deficit To Lose Weight - Calorie Intake For Weight Loss." The Best Diet Plan To Lose Fat, Build Muscle & Be Healthy. N.p., 13 Aug. 2013. Web. 27 July 2017.

Hussman, John P., Ph.D. "Caloric Deficits and Fat Loss." Hussman Fitness - The Scale: Caloric Deficits and Fat Loss. N.p., n.d. Web. 27 July 2017.

Johnson, Andrea. "Process of Losing Weight." LIVESTRONG.COM. Leaf Group, 18 July 2017. Web. 27 July 2017.

"What Happens When Fat Is Burned?" Muscle & Strength. N.p., 18 Feb. 2012. Web. 27 July 2017.

Wilson, Lindsay. "What Is a Calorie Deficit and How Does It Cause Weight Loss?" FitFolk. N.p., 05 Apr. 2017. Web. 27 July 2017.