You may have experienced it yourself: you have tried countless diets, repeatedly calculated your daily calorie requirements using various calorie calculators, and yet weight loss success remains elusive? It can be extremely frustrating and discouraging when you try so hard and still see no progress. If this sounds familiar, you are not alone.
The path to a healthy weight and well-being is sometimes not that simple. One of the greatest challenges lies in precisely determining your individual daily requirement of calories and nutrients. But even though the basal metabolic rate and the active metabolic rate are important components for calculating your energy balance, relying solely on numbers is not enough.
In this article, we want to help you better understand the numbers and show you why calculating your daily requirement alone is often insufficient. The key to sustainable success lies in the combination of knowledge, self-observation, and flexibility.
Losing weight with weight loss injections
GLP-1 medications, often referred to as weight loss injections, have established themselves as effective aids for weight reduction and the treatment of type 2 diabetes. These medications work by reducing feelings of hunger and increasing the feeling of satiety, which leads to a reduced calorie intake. However, even with the support of GLP-1 medications, understanding and calculating your own energy requirements remains essential for weight loss success. A calorie deficit is necessary to lose body weight, and to achieve this, it is important to know and calculate your own basal metabolic rate and daily energy requirement. In the following, we show how you can calculate your energy requirement and the necessary calorie deficit to have a benchmark for losing weight effectively.
Calculating daily requirements: Kilocalories or Kilojoules?
In the world of nutrition and energy calculation, we encounter the terms "calories," "kilocalories" (kcal), and "kilojoules" (kJ), which all represent different units of measurement for energy. The term "calorie" is originally derived from the Latin word "calor" (heat) and describes the amount of energy required to heat one gram of water by 1 degree Celsius. However, this definition is not entirely precise, as it depends on ambient pressure, the water used, and other factors. Kilocalories (kcal) are the larger unit of measurement commonly used in nutrition. 1 kilocalorie corresponds to 1000 calories.
Kilojoules (kJ) are an alternative unit of measurement for energy, which allows for more accurate measurement because they are directly linked to the international SI unit system for energy. 1 kilocalorie corresponds to approximately 4.184 kilojoules. Kilojoules offer a more precise calculation of the energy content of foods and are more common in scientific circles as well as in some countries like Australia and New Zealand.
Why do we calculate with kilocalories instead of kilojoules?
The use of kilocalories instead of kilojoules is largely historical and based on practical reasons:
Kilocalories have long been established as a unit of measurement in nutrition and are used worldwide. Consumers are familiar with the listing of kilocalories on food packaging, which simplifies communication and understanding.
Many people have an intuitive understanding of how much energy a certain amount of kilocalories in food represents. This makes it easier to handle the information in everyday life and allows for an easier comparison between different products.
We also prefer calculating with kilocalories (kcal) rather than kilojoules (kJ) because the values in kcal are lower and thus easier to manage and understand.
Basal metabolic rate or resting energy expenditure?
When we want to calculate calorie requirements individually, we often encounter the terms basal metabolic rate (BMR) and resting energy expenditure (REE). Both terms are often used synonymously.
Basal Metabolic Rate (BMR):
The BMR indicates the value of calories that your body requires in complete rest, at a neutral ambient temperature, and after a 12-hour fasting period to maintain basic vital functions.
In everyday life, however, it is rarely possible to create such ideal conditions, so the amount of energy referred to as the basal metabolic rate represents the resting energy value.
Resting Energy Expenditure (REE):
The REE is the amount of calories you should consume at rest under less strict, everyday conditions. The REE is generally slightly higher than the BMR, as it takes digestion and small activities into account, since we are still moving slightly, even when we are at rest.
The basal metabolic rate accounts for up to 75% of an individual's total daily energy expenditure. Women have an approximately 10 percent lower basal metabolic rate than men, because fat-free body mass consumes more energy and women, due to genetics, have a higher body fat percentage and less muscle mass than men.
Increasing the resting energy expenditure is a challenge, as it is largely determined by genetics, age, gender, and body composition. However, there are some strategies that can help increase REE, especially if you want to lose weight:
Thermogenesis through nutrition
Certain foods and diets can increase the thermic effect of food (TEF), which can have a small but significant impact on REE.
- Protein-rich diet: Protein has a higher thermic effect than carbohydrates and fats, which means more energy is consumed for the digestion and processing of protein.
- Regular meals: More frequent, smaller meals also increase the thermic effect.
Cold exposure
The body consumes more energy to maintain body temperature when exposed to cold temperatures. This way, you can even lower your "energy overheads" in winter.
- Cold showers
- Cold environment: Spend time in colder environments or lower the room temperature slightly.
Muscle building
Even if you often read that cardio training in the fat-burning zone is the first choice for the goal of weight reduction, you will reach your goal faster and more sustainably by building muscle.
Why is muscle building important?
- Increase in energy requirements: Muscles are metabolically active and consume more calories than fat tissue even at rest. The more muscle mass you build, the higher your daily energy requirement. This means your body burns more calories even when you are not active. This can accelerate the weight loss process and make it more sustainable.
- Protection against muscle loss: During a diet, there is a risk that your body will break down not only fat but also muscle mass, especially if you have a high calorie deficit. Through regular muscle-building training, you send a signal to your body that the muscles are needed. This helps to minimize muscle loss and preserve muscle mass.
- Improvement of body composition: Muscle-building training helps to improve body composition by increasing the proportion of fat-free mass. This leads to a firmer and more defined appearance. Even if your weight on the scale plateaus, your body can still change positively.
Calculating daily calorie requirements
To calculate your daily calorie requirement, you need your requirement in complete rest and in motion, i.e., the basal metabolic rate and the active metabolic rate.
The difference between BMR and REE is less relevant in practice, as both terms describe energy expenditure at rest and the differences in normal everyday life are negligible.
For most people trying to determine their calorie needs, it is sufficient to use one of the common formulas, regardless of whether it is for BMR or REE.
But this is often where the problem lies: Different formulas for calculating the basal metabolic rate lead to different results. These formulas estimate the REE. These inaccuracies arise from individual differences in body composition, metabolism, and genetic factors. Therefore, it can be extremely frustrating if you stick strictly to a calculated amount of calories and still see no progress.
Calorie consumption at rest
Harris and Benedict published the standard values for the basal metabolic rate that are still valid today as early as 1919, with different calculation formulas for women and men. For this, the parameters of age, height, and weight are used. 
Since calculating with this formula is very complex, you can also just use the approximation formula for a simple estimate.
The following Katch-McArdle formula is more accurate for estimating the BMR in individuals with a high muscle percentage.
All formulas for calculating calorie requirements for men and women apply to adults 18 years and older.
Activity level
With increasing physical activity, energy requirements increase because your body consumes energy during movement. The extent of daily muscular work varies greatly, as there is a big difference between having an office job or performing heavy physical work, and whether you count yourself among those who exercise regularly or are more of a couch potato. For this reason, in nutritional science, people are divided into five groups based on their physical activity.
The PAL factors (Physical Activity Level) were developed to calculate a person's total energy requirement based on their activity level. They were determined through research and studies that examined the relationship between physical activity and energy expenditure.
Energy requirement: How many calories do I need daily?
You can calculate your total daily energy expenditure (TDEE), i.e., your individual calorie requirement, by multiplying the REE by the corresponding PAL factor.
Note: Often, the PAL factor is overestimated and the energy supplied from food is underestimated.
Calculating active metabolic rate
The active metabolic rate is the difference between your total energy requirement and your resting energy expenditure.
Calorie calculator
Don't want to calculate your daily calorie consumption yourself?
You can also use a calorie requirement calculator, which has the formulas stored to display the average values for your daily calorie requirement, i.e., how many calories your body needs every day.
What calorie requirement for weight loss?
To lose weight long-term, you must keep your calorie intake below your daily calorie requirement. You therefore need to consume fewer calories and, ideally, also burn more energy. This is known as a negative energy balance or calorie deficit.
Do not make the calorie deficit too large! A moderate calorie deficit is typically between 300 to a maximum of 500 kcal per day. In some cases, the deficit can be increased to 1000 kcal. However, it is important to ensure that you do not reduce your calorie intake below your basal metabolic rate, as this can have negative effects on your body and can ruin your weight loss success.
What happens if you fall below your basal metabolic rate?
Since the basal metabolic rate is the amount of energy your body needs in complete rest to maintain vital functions, several negative effects can occur if you reduce your calorie intake below your basal metabolic rate:
- Yo-yo effect: Drastically reduced calorie consumption can slow down your metabolism. Your body switches to "economy mode" to save energy. As soon as you start eating normally again, your body gains weight faster, which leads to the well-known yo-yo effect, because your metabolism remains slowed down.
- Loss of muscle mass: If your body does not receive enough energy from food, it begins to break down muscle mass to gain energy. This loss can further lower your basal metabolic rate and make weight loss more difficult in the long term, because muscle burns more energy at rest than body fat.
- Stress hormones: With low calorie intake below the BMR, your body releases stress hormones like cortisol. Cortisol promotes the storage of fat, especially in the abdominal area. This happens because your body is preparing for potential famine and therefore stores energy in the form of fat.
- Decrease in daily energy requirements: Due to the slowing down of metabolism and the loss of muscle mass, your daily energy requirement drops. Your body needs fewer calories to perform the same activities, which makes it harder to continue losing weight or maintain your weight.
The right approach to a calorie deficit
To achieve a healthy calorie deficit without falling below your basal metabolic rate, you should consider the following points:
- Moderate deficit: Aim for a daily calorie deficit of 500 kcal, which you can increase to up to 1000 calories per day, as long as it does not fall below your basal metabolic rate.
- Regular meals: Distribute your calorie intake over several small meals throughout the day. This helps keep your blood sugar level stable and avoid cravings.
- Sufficient protein: Make sure you consume enough protein. Protein helps to maintain your muscles and promotes satiety.
- Exercise: Integrate regular physical activity into your everyday life.
- Stress management: Reduce stress through relaxation techniques. Less stress means lower cortisol levels, which reduces fat accumulation.
- Patience and flexibility: Weight loss is a process that requires time and patience. Be flexible and adjust your strategy if you notice that you are not making progress or feel uncomfortable.
I have a calorie surplus, what now?
If you should happen to exceed your calorie limit on a given day, or even several times in a week, this is by no means a reason to despair. Increase your physical activity in everyday life, simply reduce your calorie intake the next day as usual, and focus on active leisure activities. Keep in mind, however, that a persistent surplus will cause you to gain weight again. Therefore, it is important to repeatedly recalculate your calorie requirements to know whether you are still in a deficit.
Weight loss injections make it easier to stay in a calorie deficit and thereby lose weight effectively.
Calculating your calorie deficit and the role of weight loss injections
To lose weight successfully, it is crucial to achieve a calorie deficit. This means you consume more calories than you take in. Here are some steps and tips on how you can calculate and maintain your calorie deficit:
- Calculate your basal metabolic rate (BMR): Your BMR is the amount of calories your body burns at rest. This is the basis for calculating your daily calorie needs.
- Determine total energy expenditure: Total energy expenditure consists of your BMR and the calories you burn through physical activity. You obtain this value by multiplying your BMR by an activity factor.
- Create a calorie deficit: To lose weight, you must create a calorie deficit. A deficit of about 500 to 1,000 calories per day leads to a weight loss of about 0.5 to 1 kg per week. It is important to know that 1 kg of fat corresponds to approximately 7,000 calories.
- Role of weight loss injections: GLP-1 medications help you reach a calorie deficit more easily. They reduce hunger and increase satiety, allowing you to consume fewer calories and maintain the deficit.
- Calculate and adjust your calorie deficit: Regular adjustments to your calorie expenditure and intake are necessary to ensure you remain in a deficit. Weight loss injections help you control your appetite and minimize your calorie intake.
Losing weight with GLP-1 medication
The use of GLP-1 analogues should not lead to falling below your BMR, as long as you continue to eat enough calories per day to cover the body's basic energy needs. Here are some important points to keep in mind:
- Basal Metabolic Rate (BMR): Your personal calorie requirement remains the same, regardless of the use of GLP-1 analogues.
- Effect on appetite: GLP-1 analogues reduce appetite and increase the feeling of fullness. This can lead to eating less or feeling hungry less often. It is important to ensure that you still consume enough food to meet the BMR that your body requires.
- Monitoring and adjustment: People using GLP-1 analogues should regularly monitor their health status and diet. It may be necessary to adjust your diet to ensure that the body receives enough nutrients and energy to remain healthy.
Conclusion: "How many calories do I need to lose weight?"
A healthy calorie deficit of at least 300 calories below your daily energy requirement is the key to sustainable weight loss. But how high is your energy requirement? The calculations provide an estimate, but every body is different. Factors such as muscle mass, metabolic rate, and genetic differences also play a major role. Therefore, it is important to view the calculated values as guidelines and listen to your body. If you are not making progress, adjust your calorie intake and activity level accordingly. Also, make sure to remember that not just the quantity of calories, but also the quality of your food plays a role.
Avoid extreme diets that lower your calorie intake below your BMR. With a moderate but consistent deficit, sufficient nutrient intake, regular training to build muscle, and good stress management, you can achieve your weight loss goals and maintain your weight in the long term.
Remember, the road to your target weight is a marathon, not a sprint. Stay patient and stay on track!
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