In short, your calorie goal is based on your basal metabolic rate and your physical activity level. Depending on your goal, we also calculate an energy difference, which helps guide gradual weight loss, maintenance, or weight gain in a supportive and sustainable way 💚
👉 If you’d like to jump to a specific section, here’s a quick overview:
- Which formula Yazio uses (and why)
- How does Yazio calculate your calorie goal
- How activity level affects your calories
- How calorie deficits and surpluses work
- Why does Yazio use a moderate calorie difference
- Activity tracking and burned calories
What is my basal metabolic rate?
Your basal metabolic rate, often called BMR, describes how much energy your body needs when it’s completely at rest.
This includes energy for essential processes like:
- Breathing
- Circulation
- Temperature regulation
- Organ function
You can think of it as the energy your body needs just to keep things running, even if you were resting all day.
Which formula does Yazio use?
Yazio uses the Mifflin–St. Jeor Equation to calculate your basal metabolic rate.
We use this formula because:
- It’s considered one of the most accurate methods available (avg. 5% more)
- It performs better on average than older formulas
- It’s widely used in nutrition science
For the calculation, we use the details you entered during setup:
- Your weight, height, age, and sex
How does Yazio calculate my calorie goal with the Mifflin-St. Jeor Equation?
First, we calculate your basal metabolic rate:
- Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5
- Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161
Because daily life involves some level of movement, we then multiply your BMR by an activity factor to estimate your active metabolic rate.
When you sign up, we set your activity level between low and moderate. This is usually a good fit if you spend much of your day sitting.
You can update this anytime under:
Profile → Settings → My Goals → Activity Level.
What is the Broca Formula, and why doesn’t Yazio use it?
The Broca Formula, also known as the Broca Index, is an older method that was used to estimate a target weight.
Calculation:
- Desired normal weight in kg = Height (in cm) minus 100
- For example:
- If you are 170 cm tall, the calculated value would be 70 kg
This formula is a rough estimation. It works best for people of average height and doesn’t account for individual factors such as muscle mass or body composition.
When calorie needs are calculated using the Harris-Benedict Formula, an additional step, the Broca Index Adjustment, may be applied for a BMI of 30 kg/m² or higher. This adjustment uses an adapted body weight to better reflect energy needs.
Yazio calculates calorie needs using the Mifflin-St. Jeor Equation, which does not support a Broca Index Adjustment. We use this equation because it provides a reliable, science-based starting point for many people.
If your BMI is above 30 kg/m², you might prefer to calculate your calorie needs using the Harris-Benedict Formula together with the Broca Index Adjustment and then manually adjust your calorie goal in the app if needed ☺️
What is the activity factor?
The activity factor is a fixed value based on your daily routine and overall movement. We calculate it by looking at how active you are throughout the day and creating a weighted average.
To do this, we account for:
- Sleep (we use an average of 8 hours)
- Active time (the remaining 16 hours) → weighted by your chosen activity level.
As a new user (low to moderate activity):
- Women: 1.33
- Men: 1.36
By activity level:
- Low: 1.25
- Moderate: 1.38
- High: 1.52
- Very high: 1.65
You can update your activity level anytime under:
Profile → Settings → My Goals → Activity level
How does the energy difference work?
If your goal is to maintain your weight, your calorie goal is calculated as:
- Basal metabolic rate × Activity factor
If you want to lose or gain weight, we add an energy deficit or surplus to support gradual, sustainable progress.
- Basal metabolic rate × Activity factor + Energy difference
The default weekly change for new users is ±0.5 kg. This equals a daily adjustment of around 375 Calories. For a weekly change of 1 kg, the daily adjustment would be 750 Calories.
You can adjust this under:
Profile → Settings → My Goals → Weekly Goal
How activity tracking affects your calorie goal
If you connect Apple Health, Health Connect, or a fitness tracker, Yazio automatically factors your tracked activities into your calorie goal.
If you prefer not to include burned calories, you can change this under:
Profile → Settings → Diary & Water Tracker → Include Activities in Calorie Goal
Why does Yazio use a 750-calorie difference?
You may have heard that a weekly change of 1 kg requires a daily difference of around 1,000 Calories. This is a general reference point, but it doesn’t work the same way for everyone.
We intentionally use a slightly smaller default difference. Larger deficits can feel overwhelming, increase stress, and make it harder to meet your body’s basic energy needs. Meeting your basal metabolic rate is important for supporting essential functions and long-term well-being.
A more moderate approach helps many people stay consistent, motivated, and supported over time 🌱
You can always adjust your calorie goal manually if you have experience doing so or if you’ve discussed it with a medical professional.
If you’d like more background, you can learn more here.
💡 Good to know
This calculation is a technical estimate based on the available information. Every body is unique, and factors such as genetics, hormones, or gut health can influence energy needs.
If you feel your progress doesn’t reflect your goals, you can adjust your calorie and macronutrient targets in the app. If needed, we recommend seeking guidance from a doctor or dietitian.
If you’d like to explore other methods, these tools may be helpful:
Mifflin-St. Jeor Equation
Harris-Benedict Equation
Broca Index Formula
Katch-McArdle Formula
We hope this article was helpful and wish you lots of joy with Yazio. If you still have questions, Max is always happy to help in the chat 💬