Metabolism’s Role in Burning Body Fat

How calories are used by the body can be confusing.  Metabolism, thermogenesis, age, gender, and physical activity all play important roles.

METABOLISM  — the process by which your body converts what you eat and drink into energy – is popularly regarded as the key reason for you being thin or fat.  We like to distill things down into simple terms or concepts.  A world painted either black or white is definitive and easier to navigate.

So, is the real difference between those who are overweight and the skinny beans simply a matter of metabolism?  The skinny simply burn up their calories cause of God’s gift of a “fast” metabolism?

Let’s dig into this a bit.  I’m inspired to address this metabolism issue after having read the Editor-in-Chief of SELF magazine, Lucy Danziger’s article called, 7 Tricks to a Speedier Metabolism. My sense is that her “tricks” (listed below) are worth knowing about and implementing, but they do not necessarily act mainly on metabolism.

Let’s turn to the Mayo Clinic for clarity, which says this here:

“…contrary to common belief, a slow metabolism is rarely the cause of excess weight gain. Although your metabolism influences your body’s basic energy needs, it’s your food and beverage intake and your physical activity that ultimately determine how much you weigh.”

The term “metabolism” or “basal metabolic rate” (“BMR”) is the number of calories your body uses to carry out some basic functions, such as biochemically processing calories and oxygen to realize the energy used by your body.  Even at rest, you need to breathe, blood needs to circulate, hormones adjust and cells repair and grow.  All this requires energy/calories/metabolism.

On average, 60 to 75% of the calories you use to fuel the process of these basic functions are fairly consistent and fixed. That said, there is more to metabolism when it comes to burning calories.  About 10% of the calories used each day is used for thermogenesis – the digesting, absorbing, transporting and storing the food you consume.  And the rest of the calories used is from physical activity and exercise, whether it’s running up a hill, or carrying groceries from the car to the home.

[Read Lose Weight without Dieting, a primer on thermogenesis.]

Determinants of BMR

There are three basic factors that determine your basal metabolic rate (BMR):

  • Your body size and composition. Even while resting, the bodies of people who are larger or have more muscle burn up more calories.
  • Your sex. Men usually have less body fat and more muscle than do women of the same age and weight, and muscle burns more calories, even with the body at rest.
  • Your age. As you get older, the amount of muscle tends to decrease and fat accounts for more of your weight, slowing down calorie burning.  This is why it’s so important to engage in weight-bearing exercise (walking up hills, calisthenics, weight lifting) as you get older, so that muscle tissue is retained.

Although it may be tempting to blame your metabolism for weight gain, only rarely is this the case. Instead, what’s true is that weight gain is most commonly the result of eating more calories than you burn. Yes, it’s pretty black and white after all: To lose weight, you need to create an energy deficit by eating fewer calories, increasing the number of calories you burn through physical activity, or both.

So, with that primer on metabolism behind us, let’s return to the “7 tricks” that Ms. Danzinger wrote about.  I contend that rather than principally effecting metabolism, these tricks mainly influence  thermogenises, that being the calories digesting, absorbing, transporting and storing the food you consume.  Nonetheless, I think what she presents would be helpful to someone trying to lose body fat, and so I’ll summarize them, and if you wish to delve deeper, read her 7 Tricks to a Speedier Metabolism here.

7 Tricks to Speed Up Calorie Burning While at Rest

1. Scrimping on shut-eye

In a study of more than 68,000 women, those who slept seven hours weighed 5.5 pounds less than women who slept five hours or less.

2. Stressing out

Stress has a deleterious effect on your thyroid, a gland that regulates metabolism and protein synthesis, among other things. If not working properly, you can gain weight, feel depressed and fatigued.

3. Skipping breakfast

Miss breakfast and you’ll have less energy and likely eat more later than you would if a good quality breakfast was eaten.  What you eat for breakfast is important… try to consume all three macronutrients: protein, complex carbs and a high quality (omega-3) fat.  Try an omelet made with 4 egg whites, 1/2 cup chopped broccoli, 1/4 cup chopped onion and 1 oz lowfat shredded cheese; it delivers an impressive 22 g protein per serving.

4. Staying seated

Sitting for a few hours switches off enzymes that capture fat in the bloodstream, but standing up and getting active reignites them. Stand when possible.

5. Eating junk food

Junk food might stimulate a gene that encourages your body to store excess fat, causing you to gain weight over time.  Dampen sweet cravings with berries or an orange, both of which are high in vitamin C, a nutrient that can help you sizzle up to 30 percent more fat during exercise.

6. Falling into a workout rut

As you get closer to your weight goal, there’s less body mass to consume calories, so you need fewer of them.  Rather than get upset, revamp your workouts and try different quality foods.

7. Dodging the weight room

Lifting weights helps you build calorie-burning lean muscle, and with more lean muscle, you use more calories even when just sitting at your desk or lying on the bed.  Add weight-bearing exercises like planks, lunges, squats and tricep dips to your workouts three times a week, and/or develop a rigorous yoga routine that requires lifting your body up and down off the floor.

Good luck and have fun — let all great things be done with a light heart.

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Joe Garma

I help people live with more vitality and strength. I'm a big believer in sustainability, and am a bit nutty about optimizing my diet, supplements, hormones and exercise. To get exclusive Updates, tips and be on your way to a stronger, more youthful body, join my weekly Newsletter. You can also find me on LinkedIn, Twitter and Instagram.