Calories: the importance of calculating and tracking them

Calories: the importance of calculating and tracking them

Why is it important to know how many calories we consume daily?

1. What is a calorie? (1)

A calorie is a unit of energy measurement. In nutrition, when we talk about calories, we mean getting energy from food or drink and consuming energy through physical activity.

There are 2 types of calories:

  1. calorie (cal symbol): 1cal is the amount of energy needed to raise the temperature of one gram of water by 1 degree Celsius
  2. Calorie (Cal symbol, kcal): 1kcal is the amount of energy needed to raise the temperature of one kilogram of water by 1 degree Celsius

1 Calorie (1 kcal) = 1000 calories

The calories included in the nutritional values displayed on the boxes of different foods refer to Cal (kcal). So, if 100 grams of uncooked white rice have 370 calories, they are actually 370 kcal = 370,000 cal.

To be simple, when it comes to energy intake or consumption, kcal or Calorie High is used.


100 gr peeled bananas = 80kcal (I get 80 Calories)

30 min of fast walking on the treadmill = 200kcal (200 calories)

2. Energy balance and the first law of thermodynamics (2)

Human physiology conforms to the first law of thermodynamics, which states that energy can be transformed from one form to another but cannot be created or destroyed.

When we apply this law to the human body we get the following formula:

Es = Ei – Eo

Es = rate of change of macronutrient storage in the body

Ei = ingested energy (energy from food and drink)

Eo = energy consumed (energy consumed by the body to support vital organ functions + energy consumed during physical activity of any kind)

Thus we have the following situations:

  1. ABSOLUTE BALANCE = Calories obtained from food = Calories consumed
  2. POTIVE BALANCE = Calories obtained from food > Calories consumed
  3. NEGATIVE BALANCE = Calories obtained from food < Calories consumed

In a 24-hour period, a person usually eats several meals, achieving a positive energy balance after each meal. Eo (Energy Expended) is largely constant during the day except for those brief moments when physical activity is increased (e.g. 1 hour spent in the gym, or 1 hour of cardio type activity), after which it is drastically reduced during sleep.

The energy balance varies quite a lot over a 24-hour period, which leads to a dynamic change in Es (rate of change of storage). Most adults do not have the same daily food intake and energy consumption so over a long period of time achieving absolute energy balance and maintaining the same body weight is almost impossible.

If over a long period of time the energy balance is POSITIVE, i.e. Calories gained > Calories used (consumed), the body tends to store energy that it does not use in adipose tissue (body fat). There are exceptions to this rule. When an anaerobic stimulus is introduced (through strength training aimed at muscle growth) part of the excess calories, and therefore macronutrients, is used for repair and growth of muscle tissue, while part is stored. A large and constant caloric surplus, a sedentary lifestyle and lack of physical activity over a long period of time leads to weight gain and is directly associated with obesity.

If over a long period of time the Energy Balance is NEGATIVE, i.e. Calories gained < Calories used and energy consumption is increased by increasing physical activity and/or decreasing food consumption, as the body needs extra energy to sustain physical activity and tends to use energy reserves that have already been stored (in the form of fat tissue). The easiest way to understand and use the principle of energy balance to our advantage is the following example: the daily calorie requirement of a person who is mostly sedentary is 2100 kcal. This person does not know how to use the principle of energy balance, does not know how to track their calories from food and eating, has no knowledge of what macronutrients are and has the following eating habits. Tuesday: gets 1700 kcal, because he didn’t have much appetite, or maybe he didn’t actually have time to eat enough due to worry (negative balance results). Wednesday: gets 2900 kcal, had appetite, got a caloric surplus (positive balance results). Thursday: gets 3500 kcal, celebrated a birthday, ate pizza and cake in addition to the food he normally eats during the day. Friday: gets 1800 kcal, ate less due to feeling guilty after Thursday’s “feast”. Saturday: get 2400 kcal, it’s the weekend, no more guilt, ate a little more than you should. Sunday: got 2600 kcal, went to visit relatives, ate traditional Romanian food, consumed alcohol, tasted cakes. How many of you found yourself in the example above? Daily average: (2100+1700+2900+3500+1800+2400+2600)/7 = 2429 kcal Daily calorie requirement: 2100 kcal Result: POOR BALANCE = > CALORIC SURPLUS i.e. 2429 – 2100 = 329 kcal

At first glance, this 329 kcal does not seem to be a large daily surplus, but, if theoretically, repeating these eating habits over a period of 1 week would result in a weekly surplus of 2303 kcal, in 52 weeks (about 1 year) it would result in time a caloric surplus of 119756 kcal, which is not negligible.

Considering the theory that 454 grams (1 pound) of body fat represents 3500 unused kcal (3) (4) (this theory is not necessarily correct in the long run, due to metabolic adaptation and hormonal response, but we will use it for the sake of example), 119756 kcal would result in a storage of 15.53 kg of body fat in a year. Although in practice there would not be an accumulation of 15.53kg of adipose tissue due to several factors (daily fluctuations in energy balance, metabolic adaptation, hormonal response, etc.), it is understood from this example how caloric surplus over time leads to increased body fat, especially if this surplus is not accompanied by a training structure consisting of anaerobic exercises oriented towards muscle hypertrophy and/or strength increase and occasional aerobic activity.


  1. In order to achieve weight loss (to force the body to use energy from fat tissue) it is necessary to achieve a negative energy balance, i.e. to have a CALORIC DEFICIT: CALORIES IN < CALORIES EXHAUSTED
  2. To obtain a weight gain (in order to force the body to use energy and therefore macronutrients from food to repair and grow muscle tissue) it is necessary to achieve a positive energy balance i.e. to have a CALORIE SURPLUS: CALORIES ENTERING > CALORIES USED (combined with specific, muscle-building workouts)
  3. CONSISTENCY IS IMPORTANT. The energy obtained from food consumption must be tracked both daily and over a long period of time, the more carefully it is tracked the more the body is forced to move in the desired direction and the results are optimized.

WARNING: the calorie calculation is only a first step in optimizing the results. Although energy balance is important, the source of these calories (macronutrients) is equally important. More details about Macronutrients in a future article.

3. Theoretical calculation of daily calorie requirements

There are several formulas for determining daily caloric needs, but they all use broadly the following approach: determine a person’s BMR (Basal Metabolic Rate), then multiply this value by an activity quotient. The coefficient is obtained according to the frequency and type of weekly activity.

One of the most widely used methods of calculating the RMB is the Mifflin – St Jeor equation

  • For Men: RMB = 10 * Weight(kg) + 6.25 * Height(cm) – 5 * Age(years) + 5
  • For Women: RMB = 10 * Weight(kg) + 6.25 * Height(cm) – 5 * Age(years) – 161

In order to help as many people as possible to determine their daily caloric needs, we have created a calculator dedicated to this, so you just have to press the button below and enter the necessary data.

In order to better understand how to use the computer, let’s take the following example:

Meet Ion. He has a static job, office work 8 hours a day, goes to the gym 3 times a week but has no set workout structure for progress, does cardio 1 time a week through a little cycling or a football match with friends. Ion has the following characteristics:

Age: 26 years old

Gender: Male

Height Cm: 180 cm ( 5` 11″)

Weight: 80 kg

Activity level: low ( 1 – 3 workouts per week )

Using the computer, Ion obtained the following results:

Calorie requirement : 2475 kcal

RMB: 1800 kcal

Fat Burning: 1975 kcal

Ion’s chosen objective is fat burning, so he is oriented to

be daily in a caloric deficit, so he should consume about 1975 kcal daily.

The daily caloric requirement is only the first step, to optimize the results it is necessary to determine the ratio of

Accurate determination of macronutrients, depending on the person, purpose, etc, requires a careful special attention.

This will be covered in the next article, so don’t forget to sign up to the NEWSLETTER (using the form on the right) to receive updates, tips and articles by email.


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Calories: the importance of calculating and tracking them
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