Tablet with image showing calories on the display

How to calculate your daily energy requirement

Understanding daily energy requirement and how it relates to your fat loss/weight loss /weight gain goal is the key. In this article, you will read about the energy requirements your body has depending on your goal, how to calculate that and we’ll also talk a little about energy balance and few other important aspects that play a vital role when it comes to adequate energy intake.

Let’s jump straight into it.

Metabolism

When we eat and drink, we supply the body with nutrition, which once digested act as a source of energy which is either stored for later or used straight away. The body uses this energy for every single process that happens, from respiration to digestion right down to chemical reactions on a cellular level, this is what we call Metabolism. In addition to the metabolic rate you have at rest (which is your Resting Metabolic Rate, but about that later) we also burn energy when we are moving around doing exercise. More the physical activity, the more energy you’ll need, this is what further increases your metabolism.

Think of metabolism as a fireplace but inside your body, basically, every single cell of your body has some metabolic need (energy requirement) to function efficiently, maintain its self and for all chemical reactions to occur. Some cells in your body have higher demand than others, for example, a muscle cell will have higher energy requirement than a fat cell but about that later. To find out how much energy your body needs you have to understand there are various physiological actions which play a vital part in metabolism.

These are:

  • BMR – Basal Metabolic Rate
  • RMR – Resting Metabolic Rate
  • Thermic effect of feeding
  • Exercise activity
  • Non-exercise activity thermogenesis (let’s call it Activities of daily living)

As you can see, there is a total of 5 components at play, but for the sake of not going too technical we’ll just concern with three key ones:

  • Resting metabolic rate
    Level of energy required to sustain the body’s vital functions at rest
  • Exercise activity
    Physical movement performed as part of structured training program
  • Activities of daily living
    Activities that you do as part of your daily routine, like commuting to work or brushing your teeth in the morning and so forth.


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Unit of energy

Ok so now that you are aware there are physiological actions that affect the metabolic rate, we’ll have a look at energy value of food called Joule.

Hint: Understanding this is going to be important for you later once you decide to get more organized with your food intake and start to keep an eye on food labels 🙂

Although Joule is the standard unit for energy, often you’ll hear the term calorie, which is also a unit of energy but with a different value to it.  In addition to that, there are bigger units of the two above, Kilojoules (kJ) and Calories (Cal, sometimes also called Kilocalorie – kcal).  Most food labels these days use both the units (kJ and Cal). You will also come across places that only use one (e.g. restaurant menu), so it makes sense to know how to calculate both when you are trying to stick to a good nutrition plan to match your weight or body composition goals.


Here is simple conversion:
1 Kilojoule (Kj) = 1000 Joules
1 Calorie (Cal / kcal) = 1000 calories
1 calorie = 4.184 Joules
1 Calorie = 4184 Joules


The important thing to point out here is that out of all the organ systems in your body, the muscular system is the most important one to consider when it comes to achieving healthy body composition,  good health and improved performance. From body composition perspective if you are looking to lose fat, for example, you’ll want to increase your muscle mass and reduce body fat, and this is where well-managed energy balance comes in.

Energy in, energy out

Energy balance represents the relationship between the energy you put in and energy you burn (through the process of metabolism). This balance will dictate whether you maintain, lose or gain weight. However, it is important to understand that there is a lot more to energy balance then it’s outcome being solely on a number on the scale.

Intense negative energy balance does lead to weight loss, but unfortunately also lead to slow down or complete shut down of “non-survival” functions like metabolic function, reproductive function and brain function (typically shown by decreased ability to concentrate).

Positive energy balance from overfeeding (and under exercising) will, on the other hand, lead to weight gain, build up of plaque in arteries, increased blood pressure, cholesterol, insulin resistances (which can further lead to diabetes) increased a risk of certain cancers and so on.

If you want to lose excess fat and lean up

If you want to lose excess fat and lean up, you’ll need to decrease your daily energy intake just slightly. We suggest you try something more realistic and manageable long term such as up to 10% adjustment on your daily energy intake until you reach your goal, which is a lot more sensible approach and will allow you to keep your results going forward, especially when combined with regular exercise and healthy nutrition intake

If you want to gain weight

If you want to gain weight, you’ll simply do the opposite, increase your intake by up to 10% of overall kcal/day. This goal is ideal for someone who wants to improve not just the number on the scale but also someone who wants increase lean muscle mass. To make your nutrition intake a right match to your goal you must focus not only on correct energy consumption but also you must make sure your food is nutritiously dense as opposed to eating food that is high in energy but low in essential nutrients. That is where making sure that your nutrition has a right balance of all three key macronutrients, protein, carbohydrates and healthy fats, along with micronutrient-rich foods like dark colored vegetables and some fruit to provide the additional vitamins and minerals is a key for your body to perform at its most optimal.

Here is how to Calculate your Daily Energy Intake

To calculate your Daily Energy Intake to match your Energy needs to reach your goal there are two steps you’ll need to take:

  • Step 1 – Calculate your Resting Metabolic Rate (RMR)
  • Step 2 – Adjust your RMR by your additional energy requirement based on your Physical Activity Levels

Step 1 – Calculate your Resting Metabolic Rate (RMR)
The first step is to calculate your Resting Metabolic Rate (RMR) which takes into account your current bodyweight, your height, and your age. The result of this calculation will indicate how much energy you need to supply to your body daily. For this, we use a relatively simple mathematical formula called “Harris-Benedict Equation for Resting Metabolic Rate” , which is by far the most commonly used predictive equation.


For men:
RMR (in kcal/day) = 66.5 + (13.75 x weight in kilograms) + (5 x height in centimeters) – (6.76 x age in years)

For women:
RMR (in kcal/day) = 665 + (9.56 x weight in kilograms) + (1.85 x height in centimeters) – (4.68 x age in years)

Note: The Harris-benedict equation has a weight adjustment for desired or ideal weight. If weight loss or weight gain is a goal use the following formula, plugging the adjusted weight (in kg) into the formulas above:

Adjusted weight (in kg) = [(actual body weight in kg – ideal weight in kg) x 0.25] + ideal weight in kg


READ THIS >> The important thing to point out here is that this is only a predictive formula so you should never take the result of this method as a definite as you may be disappointed later. Metabolism is very complex and additional aspects have an impact on your energy requirements. Nevertheless, this will provide you with a reasonable estimate of your average energy expenditure, which is better than nothing.

Fat Loss should be a goal for everyone since cutting bodyfat will help decrease your body weight (if you are overweight) and contribute to reducing the risk of developing various cardiovascular diseases and reduce your chances of becoming diabetic.


Step 2. Adjust your RMR by your additional energy requirement based on your Physical Activity Levels
This one is pretty simple; you’ll need to decide how active you are from the below list and then use it as a multiplier of your RMR Calculation you’ve done in Step 1.


  • Lifestyle                         Example                          Physical Activity (PAL)
  • Sedentary                      Little or no exercise      1.4 – 1.69
  • Moderately Active       1 hour exercise / day     1.7 – 1.99
  • Vigorously Active        2 hours exercise / day   2 – 2.4
  • Extremely Active         Competitive athlete       > 2.4

Here is an example how the calculation works:

Weight loss example:
40 y.o. male, sedentary who is 130 kg, 183cm tall trying to lose weight to get to 100 kg

  • PAL = 1.4
  • Age = 40
  • Height = 183
  • Weight = 130
  • Goal = 100 kg body weight

First, we need to calculate the adjusted body weight:
Adjusted weight = [(actual body weight in kg – ideal weight in kg) x 0.25] + ideal weight in kg
Adjusted weight = [(130 – 100) x 0.25] + 100
Adjusted weight = 107.5 kg

And now we calculate the RMR taking into account the desired goal weight being 100kg bodyweight
RMR (in kcal/day) = 66.5 + (13.75 x weight in kilograms) + (5 x height in centimeters) – (6.76 x age in years)
RMR (in kcal/day) = 66.5 + (13.75 x 107.5) + (5 x 183) – (6.76 x 40)
RMR (in kcal/day) = 2189 kcal / day

Lastly, we apply the PAL multiplier the result from RMR (since this man is sedentary and overweight we’ll select lower number from the PAL, 1.4)
DER = RMR x PAL
DER = 2189 x 1.4
DER = 3064 kcal / day

This guy will need to stay around 3064 kcal/day to achieve his weight loss goal. Now you are probably going to ask a question “Do I have to count calories and I’m good? ” Answer is a definite NO.
Reason being is a calorie is not just a calorie. Some nutrients have more calories and some less. For example, one gram of fat contains nine calories but when we compare this to protein or carbohydrates, which each contain four calories per gram; you can see a clear difference. Also, we need to take into account other things like the effect of food on the speed of insulin response, referred to as a glycemic index. We cover this topic more in our other articles so make sure you keep an eye on our blog.

Now if this man in our example started an exercise program where he’d train 3x / week for an hour we’d then adjust the DER by selecting new PAL and recalculate DER. That is important as a lot of people tend to forget to increase their energy intake when they start to exercise program thinking they can speed up the progress of weight loss. Unfortunately, this strategy typically leads to poor results as the working muscles don’t receive enough required nutrients to recover and grow which leads to muscle loss which in turns slows down the metabolism.

 


Here are general guidelines for body fat % to help you set your body composition goal:

Male body fat % chart VITFIT Personal Training Sydney

Male body fat % chart VITFIT Personal Training Sydney

Female body fat % chart VITFIT Personal Training Sydney

Female body fat % chart VITFIT Personal Training Sydney

 

Fat Loss should be a goal for everyone since cutting bodyfat will help decrease your body weight (if you are overweight) and contribute to reducing the risk of developing various cardiovascular diseases and reduce your chances of becoming diabetic.

Feel free to comment down below any questions you may have and we’ll answer them 🙂

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About the Author

Vit Muller

Vit is a passionate entrepreneur and health & fitness professional with over 6 years of experience in the fitness industry with skills ranging from business management, fitness facilities management and people management with priority always being helping others achieve their true physical potential and all round healthy lifestyle.

 

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