Energy Balance: Beyond Calories In and Out

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A Comprehensive Guide

Article reposted with permission from The Health Hub.

Properly fueling ourselves with the right amount of energy is important to health and well-being. Most of the time this topic is discussed in the context of eating less to lose weight but understanding the topic of energy balance goes far beyond weight loss and losing weight.

So, in this article, we'll discuss the topic of energy balance: beyond weight loss. We'll address what energy balance means, why it's important for our long-term health, the various aspects that contribute to energy balance, why it's harder for some people to lose weight, break down common weight loss myths, and more.

So, let’s start with a simple definition of energy balance.

What Is Energy Balance?

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Energy balance is the difference between the amount of energy that your body is using for fuel and the amount of energy that you consume through food.

Energy Intake – Energy Expenditure = Energy Balance

If you expend more energy than you consume, you will be in a negative energy balance and you will lose body mass.

If you consume more than you are expending, you will be in a positive energy balance and you will gain body mass.

If you are consuming the same amount of energy that your body is expending, you will be at maintenance and your body mass will stay stable.

There are people who attempt to disagree with this concept for various reasons we will discuss. However, at a foundational level, it really is that simple. In practice, it gets MUCH more complicated which is why it is important to understand the various factors that can impact this energy balance equation, so it doesn’t feel like an unsolved mystery. Which is what we are going to help you do with this article.

But first I want to get one of the biggest sources of frustration for many people out of the way which is unexplained weight fluctuations.

Weight Fluctuations Explained

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​The first thing I want to get out of the way is daily weight fluctuations, as I know these can be very frustrating for many people. These day-to-day fluctuations ARE NOT DRIVEN BY CHANGES IN BODY MASS, but instead are mostly driven by fluid retention. These can drive substantial changes in scale weight (up to 5%) despite no actual mass changes.

Extra water retention can be caused by eating lots of sodium or carbohydrates, Intense exercise, stress, hormonal changes, and lack of sleep. Each of these factors can contribute to our body holding onto extra water, which can cause the scale to go up overnight.

These fluctuations can be a huge source of stress and frustration for someone who tracks their body weight and doesn’t understand them.

This is why it is very important not to get caught up in single-time point scale measurements. It is instead better to take your weight under the same conditions (e.g., right when you wake up) on multiple days and track averages over time which will give you an accurate picture of your true weight. If you are trying to make modifications to your body weight, I recommend either weighing daily or on a few set days during the week (M, W, F) to get an accurate picture of your current weight and weight changes over time.

A scale that is connected to an app that will keep that information stored for you can be a useful tool here. This is the one that I have used and recommended in the past. It is inexpensive and has an app that will track the data automatically for you:

Tracking weight is not something that I recommend everyone do. If you don’t have a good relationship with the scale and your weight, then it may not be best to track at this time. However, the information does provide feedback about energy balance and is a useful tool for anyone who wants to make modifications to their body composition.

Now that we've gotten that part out of the way, let’s discuss energy and body mass changes. We will start by discussing the basic unit of energy: calories.

Calories are a Unit of Energy

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We measure energy balance with calories. A calorie is simply a unit of energy, just like a fluid ounce is a measure of volume. You may have heard the claim that “not all calories are created equal” or “calories from healthy foods are different than calories from unhealthy foods”. This is not true. This is like saying that a pound of feathers weighs less than a pound of gold. They are the same, just like a calorie from broccoli is the same as a calorie from sugar. As a unit of energy, a calorie is a calorie.

With that said, different foods can contribute to differential effects within the body that can cause those calories to contribute to weight gain/loss differently. Some foods are more filling than others due to their composition of fiber, protein, and fat. Some calories take more energy to break down and utilize for fuel. Some are simply not absorbed as well in our digestive tract. All these factors can impact how calories from certain foods may impact energy balance. This is where things can get more complicated, but it doesn’t change the simple fact that a calorie is a unit of energy.

So now that we have defined energy balance and discussed how energy balance is measured, let’s dive deeper into the aspects that contribute to energy balance: Energy Expenditure and Energy Intake.

Energy Expenditure and Energy Intake

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As discussed above, there are two sides to the energy balance equation:

  • Energy expenditure which is the amount of energy that our body uses
  • Energy intake is the amount of energy that we absorb into our system

Energy Expenditure is made up of 4 primary components:

  • Basal Metabolic rate – The amount of energy that our bodies use at rest to perform normal everyday functions
  • Thermic Effect of food – The amount of energy that is required to digest the foods that we eat.
  • Exercise Energy Expenditure – This is the amount of energy that we use during formal exercise.
  • Non-exercise activity thermogenesis (NEAT)- This is the amount of energy that our body is expended from all other activities besides exercise.

Out of these 4, Basal Metabolic Rate (BMR) makes up the highest amount of energy expenditure at approximately 60-75% of total energy expenditure. BMR will vary based on your height, body size, and body composition, and slightly by the number of calories that you are consuming as well (1).

Muscle drives higher resting energy expenditure than fat, so having more muscle mass can increase BMR. But this difference is often overstated as a 1 lb increase in muscle mass equates to approximately 6 additional calories of energy expenditure per day.

A large percentage of our resting energy expenditure is driven by the metabolic activity of our brain, heart, liver, and kidneys, which expend about 110, 90, 200, and 200 calories per lb of organ weight each (2). The size and metabolic activity of these organs are largely outside of our control, but the energy expenditure of these organs can contribute to why some people have higher resting energy expenditure and may find it easier to lose weight than others as well.

The thermic effect of food (TEF) accounts for approximately 10-15% of our total energy expenditure for most people. This value can vary based on the macronutrient composition of the diet, however. A higher protein diet will contribute to higher TEF since the TEF of protein is 20-30%, while carbohydrates is 5-10% and fat is 0-3% (3). TEF is also higher in higher fiber foods vs. lower fiber foods vs. those that are lower in fiber (4).

Exercise energy expenditure and NEAT account for the remainder of total energy expenditure. Of course, these specific percentages that these contribute largely depend on the amount of daily activity and exercise we perform. For example, someone running a marathon would have an exercise energy expenditure that makes up a very large % of total calories, and someone who is bed-ridden will have a very high percentage of their energy expenditure coming from BMR due to little to no energy expenditure coming from activity or exercise.

When it comes to energy intake, that is just calories that we eat and absorb. Fat provides approximately 9 calories of energy per gram, and protein and carbohydrates provide about 4 calories per gram. Within the category of carbohydrates, fiber only provides about 2 calories per gram due to the carbohydrates not being digested and available for absorption. Instead, fiber is broken down by our gut microbiota, and we absorb some energy because of this process in the form of short-chain fatty acids (5).

Every calorie that we ingest doesn’t technically contribute to energy intake due to variations in energy absorption from the food that we eat. We do absorb most of what we ingest, however, some of it is lost in the feces and not absorbed. This amount is usually quite small, around 1-2%, but can reach up to 10% of energy intake, particularly during periods of an energy surplus. The amount that we can extract from food is also impacted by the composition of the food, how well we chew the food, our gut microbiota, food preparation methods, and the composition of the diet, but all these factors usually contribute to minor differences in energy absorption (6).

As you can see, while energy balance does come down to a “simple formula” of calories in vs. calories out, it gets a lot more complicated when we dig into the details. Next, I want to cover why energy balance is an important aspect of nutrition and health.

Why is Energy Balance Important?

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There are negative consequences of insufficient and excess energy intake. Insufficient energy intake can result in loss of skeletal muscle mass, reduce bone mineral density, disturbances in hormonal status, fatigue, mental health issues, and more (7).

On the other hand, excess energy intake can lead to excess accumulation of fat in adipose tissue and other organs and high levels of energy circulating in the bloodstream (e.g. glucose, triglycerides, cholesterol, etc.), which can contribute to a range of chronic health conditions (8).

This is why it is important to consume the appropriate amounts of energy for your own body to achieve healthy metabolism and support muscle, bone, and hormonal health. Any discussion about energy balance wouldn’t be complete without some discussion about body fat, and body composition. So, in this next section, I want to dive deeper into the topic of “healthy” or “ideal” body fat a bit more and how it relates to health and well-being.

What is A “Healthy” or “Ideal” Body Fat Level?

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The simple answer to that question is the body fat you are at when you are healthy. Health is about a LOT more than body fat and depends more on your cardiovascular and metabolic health markers (HbA1C, LDL cholesterol, triglycerides, hormones, markers of inflammation, etc.) than the amount of fat that you are holding on your body.

There is a range of body fat in which one can be in good health, and there is a level that is too low and a level that is too high. This range varies from person to person due to a variety of factors (genetics, lifestyle habits, etc.). However, the value that has been shown to be associated with the lowest rates of death over time is about 22% for men and 35% for women, according to a recent study (9).

This is quite a bit higher than what most people would consider “healthy”, but the reality is that lower body fat doesn’t necessarily equal better health, as our societal narratives have led many of us to believe. Just like eating too little can have negative health consequences, too little body fat can have negative consequences. This study also isn’t saying that these values are “ideal” but where the lowest risk of death was seen.

The key is paying attention to your own body and health and the way you feel and working to get to a level that works for YOU. A level where you feel properly nourished and where your markers of cardiovascular and metabolic health are in healthy ranges – or best as they can be. Rather than chronically under-eating or over-eating, it is important to strive to be properly nourished appropriately according to our own individual needs.

So how do we figure out what our needs are? This is what we are going to cover in the next section.

How to Figure Out Your Energy Needs

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There are several online calculators that apply formulas to predict energy needs. These are not going to be 100% accurate for every person, but they are usually close. The one that I prefer is the NIH body weight planner (NIH body weight planner). I will link a guide in the show notes to help you use it to determine your energy needs if you would like.

From there, you must track your calories very closely for a period while also tracking your weight to really get an accurate determination of your true energy needs. For some people, this value is going to be higher or lower than what the online calculators tell you, so this feedback is what helps determine that accurately.

Tracking Calories

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I don’t think that tracking calories is for everyone, however, I think it can be helpful for most people for a short period of time to understand their energy needs and understand how to follow a dietary pattern that helps them meet those needs consistently.

When tracking, you must be accurate for it to be valuable. A lot of people track, but they don’t weigh/measure their food, they just estimate, and they don’t track small things like bites, licks, sips, etc., which can add up over the day and cause tracking to contribute to more confusion/frustration rather than being helpful. I have met a lot of people who have said, “calorie tracking does work for me, and it’s usually because they approached it the wrong way.

If you are tracking your energy intake closely and tracking your body weight, that will allow you to get a much better sense of what your true energy needs are. You can track via any popular app, such as MyFitnessPal or Cronometer, and there are also smart scales that directly link to apps as well that can be used for tracking purposes.

Weight Loss, Gain, and Maintenance

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If you track meticulously for a period and you are losing weight, then that will tell you, that you are in a deficit if you gain, then you are in a surplus, and if you stay stable, then you are eating at maintenance.

It has long been stated that 3,500 calories of either a deficit or surplus is required to lose or gain weight. However, new research is showing that this model isn’t entirely accurate, and it’s more complicated than a simple 3,500-calorie value (10). Weight loss tends to require less of a deficit in the early stages, and when someone has high amounts of body fat to lose and more of a deficit after some fat has been lost, there is less to lose.

As I mentioned before, how much we eat tends to impact our energy expenditure in various ways. When we eat less, our BMR can slow down a bit, and our brain can send subconscious signals throughout our body to even reduce unconscious NEAT as well. On the other hand, when we eat more, our BMR can increase, and our brain can send signals to increase NEAT.

How our specific body responds to a deficit or surplus can be a primary factor that determines our body weight and keeps us at what some people refer to as a “set point”. The set point is the weight that our body will naturally equalize at. For some people, that set point is high, and when they eat and exercise, their body does not compensate with extra physical activity, nor does it do a good job of reducing their desire to eat more, and they can gain weight a lot more easily.

For others eating in a surplus is accompanied by large increases in energy expenditure, increases in fecal energy loss, and very little increase in body weight. This is evidenced by a study published in 1990 that took identical twins and kept them in a facility for over 3 months and overfed them 1,000 calories per day, and weight gain was 3-fold higher in some twin pairs vs. others – 10 pounds vs. 30+ pounds for others (11).

The same can happen with exercise. A similar study of twins who were kept in a very controlled environment and were prescribed 1,000 calories of exercise per day showed an over 7-fold variation in weight loss (12). For some people exercising more will drive weight loss due to the added energy expenditure, and for others, no weight loss will occur due to compensation in NEAT to adjust for the extra energy expenditure from intentional exercise (13).

All of this is to say that yes, energy balance is calories in vs. calories out, but there is a range of factors that can impact either side of this equation that makes weight loss (and gain in some cases) much more difficult in actual practice. These are some of the reasons why weight loss (or weight gain) can feel impossible for some people and why it can lead to lots of frustration. Our bodies have several mechanisms that can come into play when we try to shift energy balance toward a negative or positive direction to keep our weight from changing.

Now, we are going to discuss some common myths and misconceptions about weight loss:

Weight Loss Myths and Misconceptions

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Myth 1: If You Eat Too Little, Your Body Will Go Into Starvation Mode and Gain Fat - As we discussed above, your body can adapt to a lower calorie intake by reducing basal metabolic rate and reducing the amount of NEAT that you are getting. However, these adaptations are not so large that the body will start to store fat while someone is eating a very small number of calories. What often happens is someone feels like they are “starving” because they are eating very few calories and their body is adapting, but they are often also bingeing occasionally leading to an overall calorie surplus that can contribute to what can feel like very high levels of weight loss resistance.

Myth 2: Hormones Are The Primary Factor Responsible for Weight Loss - Various hormones can play a role in regulating both appetite and energy expenditure, thereby influencing weight loss. Hormones themselves do not dictate energy balance, but they can impact energy balance by acting impacting energy expenditure or intake. Except in extreme cases, this effect is usually not very large, and rarely are hormones alone a major influence in driving weight gain (14).

Myth 3: Low-Carb or Low-Fat Diets Are Superior for Weight Loss - Studies that have compared low carbohydrate vs. low-fat diets have shown mixed results. Some studies show minor benefits for those following low-carb diets, some show benefits for those following low-fat diets, and some show similar outcomes (14-17).

The truth is most effective diet is the one that you are going to be able to adhere to, so rather than focusing on which is best, instead, focus on how you prefer eating and start there. Then if you wanted to follow a lower fat or lower carbohydrate approach to see if it offered any benefit, you could try it, but I don’t recommend getting caught up in a single approach, but rather finding what works for you.

Myth 4: Eating More Meals Helps “Boost Metabolism” - While it is true that infrequent meal patterns are associated with weight gain and greater health risks, the idea that eating 6 meals per day “boosts metabolism” is largely a myth. Instead of focusing on eating frequent small meals, it is best to focus on getting into a regular meal pattern that works best for your schedule and ideally includes a filling breakfast and at least two other filling and nutritious meals spread throughout the day (18).

Myth 5: Intermittent Fasting Has Special Weight Loss Effect - When calories are equated, practicing intermittent fasting, doesn’t seem to have any special benefit for improving body composition. For many people, sticking to a shorter eating window (e.g. eating all of your food within a 10-hour period and fasting 14 hours each day) can help maintain a reduced energy intake, which makes it a potentially useful energy management tool. However, the popular approach of skipping breakfast seems to be a suboptimal approach. Studies have shown that an approach called early time-restricted feeding, where you consume most of your calories in the morning and cut off energy intake early in the evening, is the approach that is likely to provide the most benefits (19).

Myth 6: Fat-Burning Supplements Can Assist With Weight Loss - There is no benefit from the use of “fat-burning” supplements, and some of these agents can have potentially dangerous side effects (20). Focus instead on diet, exercise, and lifestyle strategies, and if you need additional support for weight loss to improve health, working with a physician to consider some of the new weight loss medications is going to be the best strategy.


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Energy balance is a function of our energy expenditure and intake and is an important aspect for our health. While body fat can be a contributing factor to health, it is not the most important factor, and individuals can be metabolically healthy at higher body fat percentages than what societal norms often dictate. Nevertheless, consuming the appropriate amounts of energy is something that all of us can benefit from.

While the concept of energy balance and weight loss is simple, in practice creating energy deficits, or surpluses is impacted by several factors that are often outside of our conscious control and may require careful attention and greater levels of effort for some. It does come down to managing energy intake and increasing expenditure, but that can often be much more challenging in practice than it sounds on paper due to our body’s adaptive mechanisms that can often impede attempts to modify our body weight.

At the end of the day, understanding your energy needs, how to meet those needs, and how various factors may be impacting changes in body weight are important for long-term body weight maintenance. I hope this blog post gave you some insight into this topic.

If you would like to dive deeper into this topic and get some help putting it into practice, you might want to consider signing up for my Fundamentals of Healthy Fat Loss Course. This course is the practical application aspect of this topic and includes extensive information about fat loss, muscle mass retention, exercise training, and more. I am offering a limited-time $50 discount for readers of this blog post. Click here for more info.

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