Calories Out: How Does Your Metabolism Burn Calories?

Knowledge is the Antidote to Fear

My priority in my work with clients is that they not only achieve their goals, but also that they become intelligent information consumers and critical thinkers. With all of my clients, I strive to educate them so that they can be unfazed by “new studies” that pop up on the morning news or on social media, and can understand how to analyze new information and translate it into meaningful action.

This is because many, many nutrition and fitness headlines – whether on social media or on the morning news – play on fear. Fear and worry thrive in an environment of innocent ignorance. Education, on the other hand, empowers women and makes them mentally strong and resilient.

In other words, the magical antidote to fear is knowledge.

This is especially true when it comes to weight- and health-related information. Women already tend to be more targeted than men by weight-loss-related marketing and advertising, and when women are not knowledgeable about how and why their metabolic processes function the way they do, they are more susceptible to fear-inciting advertising, journalism, and media. They are more vulnerable to click-baity links leading to garbage information or products. Sometimes, they are even prone to make neurotic decisions about their health, like dieting too hard or taking questionable “supplements” to help them lose weight faster.

On the other end of the spectrum, misinformation about the metabolism can simply lead to complete inaction. Feeling that something is “wrong” with you, or that your metabolic rate is somehow too slow or even damaged (for whatever reason), can result in a total lack of troubleshooting solutions and experimenting with lifestyle changes. It’s just too hard.

At either end of the spectrum is fear and frustration, and possibly poor health.

Knowledge, education, and critical thinking, on the other hand, short-circuit frustration and failure, and pave a path to effective action, authentic confidence, and lasting results. I love talking about metabolism with my clients, because it empowers them to make sound decisions for their bodies and ignore hyped-up, fear-based media.

This month, I’m going to be exploring the topic of metabolism, inside and out. We’re going to cover:

  • Calories Out
  • Calories In
  • 5 Common Metabolism Myths, Busted
  • Fat Loss vs. Weight Loss
  • Working with Your Unique Metabolism

So let’s start with “Part I” of this five-segment series: “Calories Out.”

Burning Calories

The first thing you must understand about calories is how and why they “burn.” When you “burn” calories, you are experiencing a chemical reaction in your body. It is, put simply, your body using the energy stored in calories, either from stored fat cells or incoming food calories, for fuel. The “heat” – which has coined the term “burn” – is the chemical reaction that takes place when your body converts calories into actual energy expenditure.

When you are taking in less than food than your energy needs on a regular basis, your body begins to mobilize the calories stored in body fat to make up the difference in fuel, which results in fat loss. And no, you can’t target fat loss on your abs by doing crunches, or on your butt by doing squats – fat loss happens from all over the body, in ways that tend to be predetermined by your genetics.

Another way to look at metabolism is to simply call it “energy needs.” It’s like a budget. Let’s say your house costs $1,000 per month to rent or own. Your house requires $1,000 of energy from you. If you can’t get that $1,000 from your monthly income (let’s say you only make $800 per month), you must dip into your savings to pay your mortgage.

That is how fat loss works. If your daily food intake is not enough to cover your energy needs, your body will dip into “savings” (calories stored as body fat) to make up the difference.

So what is all this energy needed for?

Energy Needs for Survival

An absolutely huge part of your metabolism is solely dedicated to keeping you alive. Even if you relaxed in bed all day, your body would still work quite hard to keep your lungs pumping, your heart beating, your liver detoxifying, and more.

In other words, if you did not exercise at all, your metabolism would devote considerable energy to simply running the machine. Even for small women, this calorie burn is typically upwards of 1,000 per day – much more than you would likely estimate. Your body takes energy just to maintain itself.

This is called “resting metabolic rate.” This number is highly individual, and is calculated simply on height, weight, age, and sex. You can roughly figure out your RMR by multiplying your body weight by 10 (150 x 10 = 1500 calories per day, for example), but to get the most nuanced number, you should use a calculator.

Some individual factors (like hormones) can affect RMR – more on that at the end of this post, as well as in the upcoming weeks.

However, there two more extremely important ways that your body burns calories, that you can either indirectly influence or directly control to increase the daily calorie burn of your metabolism.

Non-Exercise Activity Thermogenesis

Again, this is nothing new in terms of my blog posts. But if you haven’t been convinced before, I hope to drive home today the importance of staying active outside of exercise.

Non-exercise activity thermogenesis (NEAT, for short) is the mostly unconscious moving around that you do throughout the day.

I put “mostly” unconscious, because many of the behaviors are beyond your conscious awareness (bouncing your foot when you cross your legs, for example), but a few are somewhat within the realm of control.

One of these factors that you can control is not sitting as much. This is why my online coaching clients, whether they’re one-on-one or in a group, track steps consistently and make step goals a huge part of their program. If you can resist the overall impulse of 21st-century American culture to sit all day long, you will make huge inroads in “speeding up” your metabolism.

We sit in the car on the way to work. Many of us sit at a computer at work. Then we drive home, and sit and watch TV at night. If we can replace some of those periods of sitting with conscious periods of low-intensity, non-exercise movement, we will harness the power of NEAT to drive up metabolic rate by as much as 2,000 calories per day. Does this number sound unbelievable? Believe it. Unlike 1000-calorie-torching bootcamp classes (which are completely false), NEAT has the potential to vary your metabolic rate in the quadruple digits. And I’m not even talking about exercise yet.

The extra energy that it takes for your body to maintain itself while you’re in motion (compared to sitting still) is tremendous. Since most of us can’t exercise for hours a day – as most of us aren’t professional athletes – we can still reap the benefits of this increased metabolic expenditure by simply moving a bit every time we think of it. This adds up dramatically over hours every day.

For example, some professions tend to move more than others. Mail deliverers who walk on foot, as well as teachers, tend to burn more calories per day relative to other professions.

It’s so simple, it almost seems unbelievable. The extra energy spent over 8-10 hours of activity throughout the day significantly outpaces what we can do with “formal” exercise.

Take more breaks at work. Get up to go for a quick walk. Change positions more frequently while sitting. Try to work in a standing position when you can. Pace in your office as you take a phone call. Basically, anytime you realize, “Hmm, I’ve been sitting awhile…” get up.


In terms of metabolism only, exercise is not a heavy lifter. Relative to NEAT, it burns fewer calories and does not exert as much influence on metabolic rate.


… and this is a very important “however”…

Exercise is incredibly important for a myriad of reasons that I describe in this past blog post. Strength training can blunt many of the acute experiences of aging by building and maintaining lean body mass, and can ameliorate the slowing of the metabolism with each decade.

In fact, the National Weight Control Registry has noted that many of its successful weight loss participants exercise for an hour per day to help maintain weight loss. This is a significant time investment, and well worth the effort. In the next few weeks, I am going to go into more detail in terms of how to plan exercise to get the most bang for your metabolic buck.

Suffice to say, there is a cascade of benefits that we receive from exercise that can’t be limited to a discussion of metabolic rate, so you should have a daily (or “most days”) exercise habit that is oriented around building strength and getting your heart rate up, not focusing on burning calories.

To summarize:

  • You “burn” calories by:
    • Living – this is based mostly on height, weight, age, and sex
    • Moving around – this is somewhat unconscious, but can be leveraged
    • Exercising – this is conscious and intentional
  • When you move more and exercise more, your metabolism is technically “faster” because you are burning more calories per day.
  • You lose fat when you need to recruit extra energy from stored fat, because your food intake is not sufficient to cover your energy needs (we’ll cover this next week).
  • Note: there are other “thermic effects” of body processes, like digesting food, that I am not exploring as a part of this topic, because these are inconsequential factors. They are mostly interesting factoids, not material for impactful lifestyle changes. Pro tip: don’t get hung up on teeny-tiny details like these, which – ironically – tend to be the ones that make headlines.
A Few Notes on Hormones

If you’re a woman reading this and you’re over 40, you may intuitively know that your metabolism has slowed somewhat as you have aged. I want to point out that, for many women, the change is likely not so much age, but hormones. I have written about hormones before (specifically the idea of control vs. influence), but it’s important to point out that the changes of menopause are more significant than the idea of “aging” itself.

The changes in thyroid function and hormone production that happen during perimenopause and menopause can downshift your metabolism, and this can also happen to a degree with some hormonal medications (like some birth control methods) and hormonal disruptions like PCOS. Hormones are so powerful, in fact, that they change a woman’s metabolic rate throughout the menstrual cycle each month, with periodic increases and decreases in rate.

In other words, if you’re a woman, you do not have a fixed, linear metabolic rate. This is something that you will have to “dance” with in your efforts to get leaner. You must work with yourself, not against yourself, and this is something that I will be covering in more detail in the upcoming weeks.

Stay tuned for next week, “Calories In!”

Follow-Up Questions from Last Week

If you want to jump into this free healthy living project (with weekly strategies to try out), sign up on this page to get these questions delivered directly to your inbox each week!

Last week in “‘Dessert Stomach,’ Sensory Specific Satiety, and Overeating,” we explored how some overeating can be managed simply by reducing the amount of variety available at each meal.

Answer the following questions about your experiences with last week’s post:

  • Question 1: Have you had the experience of “dessert stomach”?
  • Question 2: Which strategies sound the most do-able for you? Did you try any of them last week?
  • Question 3: How did the listed strategies impact your thinking around food variety, fullness, and psychology of eating?

E-mail these answers to me! 

Rachel Trotta

I am a Certified Personal Trainer, Fitness Nutrition Specialist, Physique and Bodybuilding Specialist, and Women's Fitness Specialist. I live in New Jersey in the NYC metro area, and I coach clients online all over the world. As a trainer and health writer, my mission is to make healthy living sustainable for the average person. I’m also a wife, mom, nature lover, runner, avid cook, weightlifting aficionado, history nerd, travel addict, and obsessive podcast listener. Get in touch!

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