Book Contents

How the Body Burns Fat

As my understanding of how the body burns fat increased, so did my ability to effectively burn it. For me, I have to understand how things work in order to have motivation and know-how to beat it. What I found however was a lot of misinformation. However, after reading many books, blogs, articles etc I found a lot of overlap I could finally trust. Plus, I put these things to practice and saw results.

I used to think that you burned your fat during workouts. You know, hit the gym or treadmill for a couple hours a few times a week to ensure you are burning calories. If more people knew the truth, there would be less gym memberships and workout plans. People feel productive “working out”, because it’s actionable. They feel the sweat. They see other people doing it so it feels good. But the idea that your main focus should be exercise is simply not true.

Now as a disclaimer, if you enjoy walking, running, biking or other “cardio” exercises for other reasons like being active, getting outside, socializing etc, fantastic. Just don’t get caught up in the idea that these are effective methods of burning fat. If you are training for a race, of course you need to condition yourself to prepare yourself for endurance. If you want to look like a body builder, yeah, you’ll need to do more than just dieting. However, I’ve just found that many people get stressed with this way of thinking. “Dang! I have to go on my run today or I won’t lose these last 5 lbs!” Sure supplementing some walking, running, biking can help this whole process, but I’m going to focus on more effective methods that take less time and less commitment. Exercise as it turns out, it only 20% of the game.

Your metabolism is your calorie burning engine. Your basal metabolic rate (BMR), or the rate at which your burn calories at rest accounts for 60 to 70 percent of your overall calorie burn. In other words, 60% - 70% of the calories you burn are when you are doing nothing at all. So the focus of any diet with the goal of losing weight has to be to increase your BMR, since you spend more time everyday in a low-active state. My estimated BMR is 1,778 / day, or 74 calories per hour (calculate yours here: Once you have your BMR you multiply it using the Harris Benedict Formula which is a multiple based on your activity level which gives you total calories needed to maintain weight. If all this sounds like a lot, just download MyFitnessPal app and it will calculate all of this for you. But now you know how it’s calculating it.

To understand calorie-burn better, let’s consider the treadmill. If I run on a treadmill for an hour it might say I burned 300 calories, but in fact I burned 226, since it also takes into account my BMR (that’s why it asks your height, weight, age). Common thinking says, "Have too much dessert? Just hit the gym the next day and work it off.” This simply does not work. A 600 calorie piece of cheese cake would require me to run for 2 hours straight to “burn it off". That doesn’t sound right.

Studies show there is a difference in 1,000 calories between feeling satisfied and feeling full. There is a difference of 2,000 to 3,000 calories between feeling full and feeling stuffed. If you went to an all you can eat buffet and ate 3,000 calories more than you mean to, you would need to run for 29 miles continuously to “burn off" that many calories. The idea of “burning off” in the gym whatever you “put on” is simply impossible.

To lose a pound of fat, you would need to burn 3,500 calories, or in other words 15.4 days of running an hour a day (if your daily intake of calories stayed the same). Our bodies aren’t that efficient at burning calories, and that’s a good thing. We wouldn’t be able to survive if we were burning hundreds of calories during physical activities. On the flip-side, if you ate 500 calories less than what is needed to maintain your weight everyday, you could lose a pound of fat in 7 days. So you do the math. What’s easier. Running an hour a day? Or eating a little less everyday? Nothing beats dieting.

After BMR calories burned, another 15-25% of calories is burned through digestion. So think about that. Up to 85% of your daily calorie burn is while you are doing nothing at all. So if you’ve heard that 80% of losing weight is diet and 20% is exercise it’s pretty accurate.

Your body also burns fat to support muscle. In fact, it takes about 3X the energy to keep muscle as it does fat. Your body is lazy and would much rather be breaking down then building up. Thus through exercise that stimulates muscle growth (more on this later) you force your body to work harder to support the muscle you are building.

If you gain 5 lbs of muscle, that will cause your body to burn 250 more calories a day to maintain it. If you continue to eat the same way you did before the muscle, you would lose a pound of fat in 14 days without doing anything. Conversely, if you lost 5 lbs of muscle because of age and ate the same, you would eat in excess 250 calories a day and gain a pound of fat in 14 days. We lose about 5 lbs of muscle every 10 years of our life, which is why each decade it’s a bit harder to control our weight unless we make adjustments.

If you consume 2,000 calories of processed carbohydrates, the metabolic cost of converting it into stored energy (bodyfat) is close to zero. However, if you consume lean meats, fruits and vegetables the metabolic cost of converting these foods into usable energy is high. This is know as the “thermic cost of digestion.” Protein is harder for your body to digest and thus takes more energy than does fat or carbs. The TEF of protein is 25%, meaning 25% of the calories of each gram of protein is burned off through digestion, whereas the TEF of carbohydrates is 5%, and is only 2% for fats. This is why Paleo and raw diets are effective. It makes your body automatically work harder to get the nutrients you need… plus fresh food is just healthier and better.

When you wake up, you’ve most likely been fasting for 8 - 12 hours. Fasting puts your body into fat-burning mode. Your body’s levels of cortisol are highest when you wake. Cortisol breaks things down, like fat into energy. Also, when you sleep your body releases growth hormone, which releases fat to be burned as fuel. At the same time, your insulin levels are low, meaning insulin is not getting in the way of burning fat. As soon as you eat something with carbs, your insulin spikes and you shut off your natural fat burning machine. When insulin is high, it inhibits the ability to burn fat.

So to sum this all up, eating properly has more impact on burning calories (which translates to your weight) then exercise does. Combining the two is like putting kerosene on the fire (more later). Your action items from this chapter are to download myfitness pal and get it setup. This will give you at least an idea of how many calories you need to burn to reach your weight loss goals.

Unfortunately, it’s not as simple as just focusing on the amount of calories to consume. If you ate the recommended amount of calories completely with carbs, you wouldn’t lose weight. We'll talk more about macronutrients later.

Key Takeaways:

  • Your metabolism burns more calories than exercise ever could
  • "Burning off" calories in the gym is a fallacy
  • 80% of your daily calorie burn is from your metabolism
  • Fresh foods and meats takes more calories to digest then processed carbs
  • When insulin spikes, your ability to burn fat halts

Next >> Insulin Control