Calorie Deficit: How Many Calories Should I Eat To Lose Weight?

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Last update: 30.04.2024

To lose weight, we need a negative calorie balance. However, it must not be too low, otherwise the kilos will be back on faster than we can buy new clothes. So how many - or rather, how few - calories should we eat to lose weight healthily?

Table of contents

Calorie requirements for survival

If we eat too little during a diet, evolution comes into play: everyone needs a certain basal metabolic rate to survive. Calories that provide us with the energy we need for our brain, circulation, breathing, organs and digestion to function.

On top of this, there is the so-called power metabolic rate. Calories that we consume to get to work, sit at our desk, go to the letterbox, clean our home or brush our teeth. Anyone who - commendably - also does sport also burns extra calories.

However, if you think that you only need to eat as little as possible to lose weight particularly quickly and effectively, you are falling right into the evolutionary trap. This is because our body switches to economy mode in times of need. If it doesn't get the minimum it needs, it reduces the basal metabolic rate and stores everything it can get as fat.

Losing weight successfully means eating enough

For a successful diet, this means that we need to eat enough on a regular basis. So much and so nutritious that our body dares to use its fat stores, leaving the valuable muscles alone.

If we eat less than our body needs, it lacks important nutrients. As our body is extremely comfortable, it prefers to use the muscles first, which is quicker than laboriously converting body fat into the energy it needs. But we absolutely have to maintain our muscles.

This means that only those who are full and sufficiently supplied with all nutrients will lose weight sustainably and without the yo-yo effect! For most women, this means not eating less than 1,500 to 1,600 calories a day for healthy and sustainable weight loss.

How do I calculate my calorie requirement?

Calorie consumption depends on your height, weight, daily activity and sport. If you want to know exactly, calculate your calorie requirement using the Harris-Benedict formula:

Basal metabolic rate for women: 655.1 + (9.6 x body weight in kg) + (1.8 x height in cm) - (4.7 x age in years)

The basal metabolic rate is then multiplied by an activity factor: Those who hardly move around multiply the resting metabolic rate by 1.2, those who are moderately active by 1.55. Those who run around a lot for work, for example as a nurse, tend to use the factor 1.8. This is then the individual calorie requirement without extra sport!

Let's take Sabine as an example. 50 years old, 65 kg and 170 cm tall, office worker, does no extra sport.
Sabine's basal metabolic rate is: approx. 1,350 kcal per day
= 655.1 + (9.6 x 65 kg) + (1.8 x 170 cm) - (4.7 x 50 years)

Your power metabolic rate (your basal metabolic rate x factor 1.55) is: 2,093 kcal

Not even that little!

Rule of thumb: a calorie deficit of 25%

If our example woman, Sabine, only eats 1,000 kcal a day, for example, she is permanently hungry and sacrifices her valuable muscle mass. She may lose more weight on the scales. This will mainly be muscle mass - because muscle is heavier than fat and water. However, her body composition does not change for the better as she loses valuable fat-free mass. At the end of her diet, the yo-yo effect strikes.

The much better way for Sabine to lose weight would be a daily calorie deficit of only around 25 per cent. She could eat around 1,570 kcal per day. This would lead to a considerable loss of body fat without hunger while maintaining her muscle mass.

If Sabine then eats enough protein and increases her muscle mass - and therefore lean body mass - with strength training, her weight loss will mainly come from fat stores.

Read our article to find out the best way to distribute your calories between the relevant macronutrients - proteins, carbohydrates and fat - and what else you can do to help your body lose weight healthily: How to lose weight after 40