Calories Unraveled: How Much Do You Need Daily and How Do You Calculate It?

Introduction

Calories – it’s a term that often pops up when it comes to nutrition, weight loss, and sports performance. But what exactly are calories? How many do you actually need per day, and how do you find out? For those who want to live healthier, build muscle mass, or lose weight, insight into calorie needs and consumption is essential. In this blog you will learn all about calories, how to calculate your energy needs, the difference between calories and joules, and practical tips for keeping track of your daily intake.

1. What exactly are calories?

Calories are a unit of measurement for energy. In nutrition, we often use the term kilocalorie (kcal), where 1 kcal equals 1000 calories. This is indicated on nutrition labels as the energy value of a product. You will find this information on almost all packaged foods, usually shown in kcal and sometimes also in kilojoules (kJ). Kilojoules are an alternative unit of energy: 1 kcal equals 4.184 kJ.

The calories in our food are converted by the body into energy that we need for both basic functions (such as breathing and sleeping) and physical activities (such as walking and exercising). The total of this energy is often referred to as the Total Daily Energy Expenditure (TDEE).

Joule vs. Calorie: What's the Difference?

In addition to calories, the unit joule (J) is sometimes used to indicate energy. Joules are the standard unit in scientific measurements and are mainly mentioned on European labels. One calorie corresponds to 4.184 joules. Below is an overview:

Energy unit	Description	Conversion
Calorie (cal)	Amount of energy to heat 1 g of water 1°C	1 cal = 4.184 J
Kilocalorie (kcal)	1000 calories, often used in food	1 kcal = 4184 J
Joule (J)	Standard SI unit for energy	1 J = 0.239 cal
Kilojoule (kJ)	1000 joules	1 kJ = 0.239 kcal

Calories per Macronutrient

In addition to calories per product, it is also important to know how much energy each of the macronutrients provides:

• Carbohydrates: 4 kcal per gram
• Proteins: 4 kcal per gram
• Fats: 9 kcal per gram
• Alcohol: 7 kcal per gram

The amount of these macronutrients in your diet determines the total number of calories. Products that contain a lot of fat, such as oil and nuts, often have a higher energy value than carbohydrate or protein-rich products. Alcohol also contains relatively many calories per gram and does not provide any nutritional substances, which is why it is often seen as 'empty' calories.

2. How many calories do you need per day?

Your daily calorie needs depend on several factors, including age, gender, height, weight, muscle mass, and activity level. To help you, below is a table of average daily calorie needs by age group. These figures are for guidance only; individual needs may vary.

Age group	Daily Calorie Needs (kcal) – Women	Daily Calorie Needs (kcal) - Men
Youth (14-18 years)	1800 – 2400 kcal	2200 – 3200 kcal
Young adults (19-25 years)	2000 – 2400 kcal	2400 – 3000 kcal
Adults (26-50 years)	1800 – 2200 kcal	2200 – 2800 kcal
Seniors (51+ years)	1800 – 2000 kcal	2000 – 2400 kcal

Source: Dutch Dietary Guidelines

Please note: these are averages. A person’s specific calorie needs can vary greatly depending on height, muscle mass, and activity level. For example, a young adult who is involved in intense sports will likely need more calories than someone with a sedentary job.

3. How does your body burn calories?

The process of energy consumption in the body can be understood using the basic principles of thermodynamics: energy cannot be created or destroyed out of nothing. This means that the calories we consume are either used by the body or stored (usually as fat).

In order to effectively use the energy you receive through calories, a continuous combustion cycle takes place in your body. This energy combustion consists of three main components:

a. Basal Metabolic Rate (BMR)

Basal metabolic rate is the amount of energy your body uses at rest for basic functions like breathing, heart rate, and temperature regulation. Your BMR often makes up 60-70% of your total daily energy expenditure. Factors like muscle mass, age, and genetics play a big role in your BMR: the more muscle mass you have, the higher your BMR.

b. Physical Activity

This is the energy you use during movement and exertion, and it varies greatly from person to person. This part of your energy expenditure is determined by your activity level and you can actively influence it by moving more or less.

c. Thermal Effect of Food (TEF)

The thermic effect of food is the energy required to digest, absorb and process food. This accounts for about 10% of your total energy expenditure. Proteins require more energy to digest than fats and carbohydrates, which can contribute to higher energy expenditure on a high-protein diet.

4. How do you calculate your daily calorie needs?

You can calculate your calorie needs by calculating your Basal Metabolic Rate (BMR) and then multiplying it by your activity level. Below are the steps for calculating this, plus an alternative method if you prefer to calculate it without a formula.

Method 1: Calculate your BMR and TDEE

1. Determine your BMR
   Your BMR indicates how many calories you burn at rest. A commonly used formula for this is the Harris-Benedict formula:
   • For men:
     BMR=88,362+(13,397×weight in kg)+(4,799×height in cm)−(5,677×age)
   • For women:
     BMR=447,593+(9,247×weight in kg)+(3,098×height in cm)−(4,330×age)
2. Calculate your Total Daily Energy Expenditure (TDEE)
   Multiply your BMR by an activity factor to calculate your TDEE, or your total energy needs for a day:
   • Little or no exercise: BMR × 1.2
   • Light activity (1-3 days per week): BMR × 1.375
   • Moderate activity (3-5 days per week): BMR × 1.55
   • Very active (6-7 days per week): BMR × 1.725
   • Extremely active (intensive sports): BMR × 1.9
3. Adjust your calorie intake to your goals
   • Losing weight: Eat 200-500 kcal less than your TDEE daily.
   • Gaining weight: Eat 200-500 kcal more than your TDEE daily.

 

Method 2: Practical Calorie Needs Testing

Another way to determine your calorie needs is to track your food for two weeks:

1. Choose a calorie intake based on the guideline above and stick to it daily.
2. Weigh yourself daily and take the average weight for each week.
3. Adjust your intake based on your weight trend:
   • If you are gaining weight, you are probably eating too many calories.
   • If you lose weight, you are not consuming enough calories.
   • Is your weight stable? Then you are probably around your maintenance level.

Repeat this method until you have determined your average calorie intake, while keeping your weight stable. This will give you an accurate insight into your energy needs.

5. How do you track your calorie intake?

Now that you know how to calculate your calorie needs, you can start tracking your calorie intake. This can be helpful for achieving specific goals, such as losing weight, gaining weight, or maintaining your weight.

Effective Methods to Track Calories:

1. Apps and Online Tools
   Popular apps like MyFitnessPal and Food offer convenient ways to track your daily calorie intake and macronutrients. These apps often also provide insight into the ratio of carbohydrates, proteins and fats. You can often add food simply by scanning the barcode of products.
2. Read Nutrition Labels
   Nutrition labels list the calories per serving, as well as the amounts of carbohydrates, proteins and fats. Keeping an eye on these will help you understand how many calories you are actually consuming.
3. Use a Food Diary
   For those who prefer manual work, a food diary can be a good option. Write down what you eat every day and calculate your calorie intake at the end of the day.

Closure

Understanding your daily calorie intake and expenditure gives you more control over your health and helps you make more conscious choices. By calculating your BMR and TDEE or practically testing your calorie needs, you get a clear picture of what your body needs. Ultimately, it's all about balance and consistency. Make sure you have an approach that fits your life and goals, so you can work on your personal goals in a healthy way.

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Sources

1. Harris, J. A., & Benedict, F. G. (1918). A Biometric Study of Basal Metabolism in Man . Carnegie Institution of Washington.
2. Nutrition Centre. Energy requirements per age category. Available via: https://www.voedingscentrum.nl