December 29


Energy Balance | One Simple Equation for Weight Loss and Weight Gain

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The energy balance equation has been around for quite a while. Most people know of it, yet lots of people try to discredit it. In short, it involves calories in versus calories out. When one is greater than the other, we see changes to our body composition.


You may have seen this referred to as CICO. This is simply an acronym for Calories In, Calories Out.

Effectively, Energy Balance = Energy Intake - Energy Output.

In other words, when the energy coming into our body through the food we eat is greater than the energy we expend from exercise, we gain weight.

Conversely, when we consume less energy than the amount we burn, we lose weight.

Lastly, when both sides of the equation are balanced, our weight stays the same. In other words, we maintain our weight.

Is the energy balance equation that accurate?

Quite simply, yes it is.

You may be sceptical. You may have read online, or some social media influencer may have told you calories don't matter. However, the principle of energy balance is tried and tested and upholds the laws of physics.

Cast your mind back to your high school science lessons.

You may or may not remember the first law of thermodynamics. Simply put, energy cannot be created nor destroyed. Instead, energy can only be transferred, or converted, into another type of energy.

For example, the human body can't create energy from nothing. We digest the food that we eat to produce energy for our bodies to function and move.

What happens to excess energy the human body consumes?

Well, when we consume a caloric excess - that is, eat more calories than we burn, the extra energy doesn't simply disappear. It has to go somewhere.

Basically, our body has two options:

  • increase the energy we expend by either moving around more or ramping up our metabolism, or
  • store the excess, in the form of body fat.

In a nutshell, if your body can't use up the extra energy, it must store it.

If you think back to your high school physics lessons, you may remember the first law of thermodynamics.

(what do you mean you don't remember?!)

The first law of thermodynamics states that we can never create or destroy energy. All we can do is convert energy from one form to another.

In practical terms, the human body converts the food we eat into energy. Likewise, any extra energy we take in doesn't just disappear.

So how come many people claim "not all calories are equal"?

Well, in simple terms, a calorie is always a calorie. It's a simple unit of measure.

However, you've probably heard not all calories are created equally.

And this leads to a lot of confusion.

Let's be clear. Eating 100 calories worth of beef is the exact same in terms of energy intake as eating 100 calories worth of table sugar.

The difference is in the nutrition, and the macro and micronutrients provided to your body.

However, that's a story for another day. For this article, we're just talking about energy balance. After all, it's energy balance that determines whether we lose or gain weight.

And in the beef vs sugar example above, the energy balance is the same.

Factors affecting energy balance and whether we lose or gain weight

Energy balance equation - calories in versus calories out determines weight loss or gain

So, we could stop there.

However, let's delve a little deeper so we can fully understand what energy balance is and how we can influence it.

At first glance, we might feel to reduce energy intake all we have to do is eat less. Similarly, to increase energy output we'd just have to move more.

After all, you've probably heard the 'key' to weight loss is to move more and eat less.

While that's true to an extent, let's look at the individual factors that can influence our energy balance within our bodies.

Factors affecting energy intake

While eating less food certainly would help with reducing energy intake, that's not all there is to it. Several factors influence the energy our bodies take in on a daily basis.

It's worth noting the factors affecting our energy balance can become quite complex. Many aspects can affect 'calories in' and also 'calories out'. For example, take your brain. It generally has a massive effect on energy output since it can effectively turn up or down its own metabolism as required.


Our hormones regulate how hungry we feel, our appetite and, in turn, our satiety. It makes sense that if we have a large appetite, then we're likely to eat more. Consequently, we'd have a higher energy intake.

Food consumed

Not only the amount but the type and nutritional quality of the food. For example, to a large extent, we are limited to what we have available to us.

Subsequently, what we have available to us is affected by a range of things too.

For example, our socioeconomic status - our income and expenditure. Even the type of area we live in can affect what food is easily available to us. If funds are tight and our budget is limited, then we may not be able to afford certain items and food.

Additionally, the foods that we find enjoyable influence our energy intake. After all, we tend to eat more of the foods we find taste good. Conversely, we tend to eat less of those foods we find less palatable.

Other factors influencing our food choices and what we eat are the energy density and macronutrient content of the food. Some foods contain high numbers of calories, with relatively little in the way of sustenance. Others, fill us up fairly quickly for fewer calories.

Lastly, the quality and regularity of our sleeping patterns influence the food that we eat. When we're tired, we feel lethargic. This in turn causes our body to crave more of the high fat, high sugar types of food. You're no doubt aware by this point that these types of food are higher calorie.

Calories absorbed

To an extent, "you are what you eat" is true. However, a more accurate portrayal would be "we are what we absorb."

Our bodies are not 100% efficient digesting machines. There are natural variances among every human being. As a result, we may not absorb all the calories from one particular foodstuff in the same way that someone else might.

How much of the calories we absorb from a portion of food is reliant upon:

  • our age
  • how the food is prepared
  • our general health status
  • our general macronutrient intake

Lastly, even our general state of energy balance can determine whether we absorb more or fewer calories from each meal!

Psychological factors affecting our energy intake

Similarly to how our sleep habits can influence our appetite, so too can our general mood and psychology affect how much or little we eat.

For example, you've probably already experienced times of extreme stress when you simply either don't feel like eating or don't want to eat. This sort of dietary regulation also occurs under times of mild stress.

Self-esteem and our overall mindset can have a big effect on our daily energy intake.

When we feel good, we tend to eat well. When we feel healthy, often we'll make healthier food choices. Unfortunately, the opposite is true too.

Our psychological state and stress levels also have a great influence on our sleep quality. And as we've already discussed, sleep quality affects energy intake.

Factors affecting energy output

Already we've looked at many factors affecting the 'energy intake' part of the energy balance equation.

Let's now look at those that affect the 'energy output' part.

Basal metabolic rate

Our basal metabolic rate, or BMR, is essentially the amount of energy our body requires just to function. Put another way, it's the energy we burn while resting.

When we go to sleep, our bodies don't switch off. Our metabolism continues, our brain is still active and many of our tissues repair and recuperate.

Our BMR is generally most affected by the size of our body. In essence, how much we weigh. Bigger bodies need more energy to keep them going.

Additionally, BMR can vary according to your hormone levels and genetics.

Similarly, your general health status - whether you suffer from any chronic conditions, etc. has a huge effect.

Again, sleep quality and age play an important part too.

Lastly, our history with dieting can have an effect. Years of so-called 'yo-yo' dieting can effectively screw up your metabolism and with it, your BMR.

Exercise and activity

Perhaps most obviously, the amount of activity we do in a day affects our energy output.

Essentially, we're talking about the calories we 'burn' by getting up and moving.

When it comes to formal exercise and gym workouts, sports matches and training sessions there are a few things that affect how many calories we expend:

  • our ability level
  • how intense the exercise session is
  • the duration of the workout
  • how often we exercise in a day or week
  • the type of activity we perform

Energy burned through 'non-exercise' activity - N.E.A.T.

You may have heard of N.E.A.T.

Here we're talking about Non-Exercise Activity Thermogenesis.

It might sound complicated but in fact, it's pretty simple. If we're up and moving around, we'll burn more calories than if we spend all day lying in bed. Or sitting in a chair.

Now again, there can be several factors that influence how much we get up and move around during the day.

Perhaps most importantly, is our general health status.

There are lots of ailments and conditions which impact our ability to move around. If we're suffering from any of those, then our energy output is likely to diminish.

Our occupation and how we go about our day-to-day business largely determines N.E.A.T.

Manual labourers, farmhands and construction workers could potentially burn thousands of calories a day just doing their job. Compare that to your average office worker who spends more than 6 hours sitting at a computer. Not much movement = not much in the way of energy output.

The energy we burn through the act of eating itself - T.E.F.

In technical terms, we call this the Thermic Effect of Feeding.

T.E.F. for short.

Basically, this is the energy it takes for our body to digest and process the food we eat. Our digestive system after all comprises many muscles. These muscles move to accomplish their task. This movement takes energy.

Generally speaking, the macronutrient profile of the food will determine its effect on T.E.F.

Foods higher in protein will generally require more energy from our body to digest. Conversely, high-fat foods require much less energy from us.

Similarly to macronutrient content, the nature of the food has a large effect.

Highly processed and manufactured foods may be absorbed quite easily by our bodies without much work. Fresh vegetables, lean meat and unrefined carbohydrates must be broken down by our digestive system before we can use them. This takes work. This work takes energy, therefore increasing our energy output. Albeit slightly.

What does this energy balance equation mean for you?

Well, if you either want to gain or lose body mass, you'll want to consider your overall energy balance.

In particular, you'll want to understand how to shift it in your favour.

Here's a list of things you can do to shift energy balance in whichever direction you want it to go.

Tips to reduce calorie intake

Aim to consumer more fibre-rich fruit and vegetables. This can bulk up your food volume and reduce the number of calories your body absorbs.

Look to increase your protein intake - this can help reduce your appetite. As a result, your overall energy intake may drop as you eat less food.

Eat mindfully, by chewing slowly and aim to tune in to your body's hunger and fullness signals. Learn to recognise what your body is telling you. Above everything, aim to stop eating once you are satisfied. Don't wait until you're stuffed, or eat food just because it's there.

Understand portion sizes and have a clear plan to help guide you in how much to eat.

To reduce hunger and cravings for sugar and fat, get adequate sleep. Every night.

Tips to increase energy output

Add cardio into your workout schedule to increase the number of calories you burn.

Incorporate resistance training and look to increase muscle mass. This can assist with boosting your BMR and help burn more energy.

Wherever possible, look to increase daily activity. Use tactics like parking further from your destination and walking the difference. Take the stairs instead of the lift or escalator. Consider wearing an activity tracker and compete with yourself over how many steps you can fit into your day.

Reduce stress and improve sleep by practising self-care strategies.

Paul Stokes Perth Personal Trainer Sports Nutritionist Group Fitness Instructor Massage Therapist

About the author

Paul Stokes

Paul Stokes BSc (Hons) is a Certified Personal Trainer, Accredited Sports Nutritionist, qualified Exercise to Music Instructor, Precision Nutrition coach, Massage Therapist and teaches 8 of the Les Mills Group Exercise programs.

He currently works in the Oil & Gas industry as a Wellness Coach, imparting his vast knowledge and experience to improve the quality of life of several hundred offshore workers.

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