In principle, your calorie goal is your basal metabolic rate plus your physical activity level. Depending on your goal, we also calculate your energy difference, which is decisive for losing or gaining weight.  

• What is the basal metabolic rate?
  Your basal metabolic rate refers to the energy your body needs for all metabolic processes when at complete rest.
  
• What is the Broca Formula?
  The Broca Formula, or the Broca Index, is an old formula used to calculate “normal weight” or “target weight.”
  
• Why doesn't YAZIO use the Broca Index Adjustment?
  YAZIO determines your calorie needs using the Mifflin-St. Jeor Equation. This equation doesn't allow for a Broca Index Adjustment. However, in most cases this isn't necessary, either.
  

• How does YAZIO calculate my calorie goal with the Mifflin-St. Jeor Equation?
  The complete equation is: Basal metabolic rate x Activity factor + Energy difference = Calorie goal.
  
  

What is the basal metabolic rate?

Your basal metabolic rate refers to the energy your body needs for all metabolic processes when at complete rest. For example, the energy needed if you were lying in bed all day and doing absolutely nothing.

Since men have a slightly different basal metabolic rate than women, there are also slight differences in the formulas. For the calculation, we use the information you provided us for your weight, height, sex, and age. We work with the Mifflin-St. Jeor Equation.

We use the Mifflin-St. Jeor Equation because it is deemed to be the most current and accurate equation. On average, it is 5 percent more accurate than the Harris-Benedict Equation, which used to qualify as the standard!

What is the Broca Formula?

The Broca Formula, or the Broca Index, is an old formula used to calculate “normal weight” or “target weight.” It was later replaced by the well-known Body Mass Index.

Calculation:

Desired normal weight in kg = Height (in cm) minus 100.

At a height of 170 cm, normal weight is calculated at 70 kg.

• Desired normal weight = Height - 100

The Broca Formula is merely an estimation and best suits individuals of average height. It also doesn’t take other body composition characteristics, such as muscle mass, into account.

Broca Index Adjustment

If using the Harris-Benedict Formula to determine calorie needs, an adjustment to the calorie calculation is required for a BMI of 30 kg/m² or more (i.e. an indication of obesity). This is because a high body fat percentage reduces the basal metabolic rate per kilogram. According to Broca, a weight adjustment is necessary in this case. This is also referred to as the Broca Index Adjustment.
The adjusted body weight is then inserted into the Harris-Benedict Formula.

Why doesn’t YAZIO use the Broca Index Adjustment?

YAZIO determines your calorie needs using the Mifflin-St. Jeor Equation. It is considered the most current and accurate formula for calculating energy needs and has largely replaced the Harris-Benedict Formula.

Unfortunately, since the Broca Index Adjustment is only possible in combination with the Harris-Benedict Formula, we cannot take it into account.

We chose to use the Mifflin-St. Jeor Equation because it is the best formula to apply to a large number of people. However, in certain cases (e.g. for obese or very small individuals) it may not be completely functional.

If your BMI is more than 30 kg/m², it may be useful to calculate your energy needs with help from the “outdated” Harris Benedict Formula + the Broca Index Adjustment and manually adjust your calorie goal within the app.

How does YAZIO calculate my calorie goal with the Mifflin-St. Jeor Equation?

The following is used to calculate your basal metabolic rate according to the Mifflin-St. Jeor Equation:

• 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

Since you’re active to some extent throughout the day, it’s important for us to multiply the basal metabolic rate with an activity factor in order to calculate your active metabolic rate. This is dependent on your daily activity level. If you just signed up with YAZIO, we set your activity level between low and moderate. For those who sit at work, this is a suitable value. You can change your activity level under Profile > Settings > My Goals > Activity Level.

The activity factor is a fixed value:

• PAL Summary  
  
• Scientific PAL Source
  
• Ranges of Activity for PAL 

As a new user (low to moderate):

• Women: 1.33
• Men: 1.36

By activity level adjustment under Profile > Settings > My Goals > Activity Level:
The activity factor is a fixed value but is determined by us in advance. In detail, we evaluate each hour of your day with its own factor. We assume you sleep 8 hours, resulting in a factor of 0.95. We then evaluate the remaining 16 active hours, depending on your activity level, with another factor to obtain a final weighted average for the calculation of the entire day: 

• Low: 1.25
• Moderate: 1.38
• High: 1.52
• Very High: 1.65

If you would like to maintain your weight, this is the final equation for your calorie goal:

• Basal metabolic rate x Activity factor

If you would like to use YAZIO to lose weight or build muscle, we also need to expand the equation with the energy difference. Depending on your goal, this will be a positive or a negative value. The equation is as follows:

The energy difference reduces or increases your calorie goal:

• (Weight difference x 750) ÷ (Weight difference ÷ Weight gain/loss difference per week)
  

The weight difference is calculated by subtracting the goal weight from the starting weight. The planned weight gain or loss per week for a new user is plus or minus 0.5 kg. That means: For a weight loss of 0.5 kg per week, we calculate a deficit of 375 Calories per day. For a maximum weight loss of 1 kg per week, the calorie deficit will be 750 Calories per day. Under Profile > Settings > My Goals > Weekly Goal, you can adjust your desired weekly goal or calorie goal.

The complete equation is as follows:

• Basal metabolic rate x Activity factor + Energy difference

If you use a tracker (e.g. Garmin, Fitbit, Apple Watch) or another app to track your activities, YAZIO will automatically adjust your calorie goal. If you do not want to take your burned calories into account, you can adjust this under Profile > Diary > Include activities

As you can see, our formula for the calculation of your daily calorie goal is based on a calorie deficit of 750 calories per day. Since this number might raise a few questions, we’ll take a quick look at why we chose this value.

According to the general rule of thumb, a weight loss of 1kg body weight per week requires a calorie deficit of 1000 calories per day. However, please keep in mind that this is only a general point of reference. Since it depends on various factors, weight loss is a very individual subject and can vary from person to person.

As mentioned above, we decided to slightly deviate from this rule of thumb. While a higher calorie deficit can sometimes initially lead to a faster weight loss, this is neither healthy nor sustainable in the long term in most cases. The higher the calorie deficit is, the higher the risk is that you consume less calories than your Basal Metabolic Rate (BMR), which is the energy your body needs in a state of complete rest to maintain vital functions. Covering at least your BMR, however, is very important because only then your body is provided with the nutrients it needs for the essential bodily functions and processes, ensuring a sustainable and healthy weight loss. You can find more information on that here.

As mentioned, a higher calorie deficit can cause you to initially lose weight so fast that you and your body cannot cope with this for long, which in turn oftentimes results in a yo-yo effect. This can be intensified by the fact that a high-calorie deficit usually also comes with a lot of stress and sacrifice, which can have significant negative physical and psychological effects.

Of course, we can understand that it is difficult to be patient with yourself and your body and choose a moderate calorie deficit, especially when you’re just getting started. However, we believe that your health and sustainability should have top priority at any time on your journey to your dream weight and healthier life. That’s why we decided to include a little “safety cushion” and base our formula for the calculation of the calorie goal on a calorie deficit of 750 instead of 1000 calories.

Many of our users have reported that this has really helped them not only to integrate the calorie deficit into their everyday life and daily routines but also to stay motivated. If you want to learn more about other users’ experiences, please feel free to take a look at our users’ amazing success stories!

That being said, you of course always have the option of manually adjusting your calorie goal in the app to perfectly fit your wants and needs. However, we only recommend this for very experienced users or after consulting a medical expert or nutritionist.

Please note:
This is a purely technical estimation of your calorie needs and how they are calculated.
Unfortunately, our equation cannot take into account the fact that every metabolism is different. Besides body height, weight, gender, and activity level, there are other factors such as genetic predisposition, hormones, and gut flora that can play an important role when determining your exact calorie requirement.
If you notice you are not getting closer to your goal with our calculated recommendations, you can also manually adjust your calorie and macronutrient goals.

If necessary, seek advice and support from a doctor or dietician.

What trustworthy online calculators would you recommend for users who want to use another formula for calorie calculation or who want to use the Broca Index? 

There are several different online calorie calculators out there using different formulas. Here you can find a short comprehensive list of some formatted options you can use:

For using the Mifflin-St. Jeor Equation:

➡️ Healthline Calculator
➡️ BMR Calculator (with in-depth explanation)

For using the Harris-Benedict Equation
➡️ Mayo Clinic Harris-Benedict Calculator  

For using the Broca Index Formula
➡️ MDApp Broca Index Calculator  

For using the Katch-McArdle Formula
➡️ Omni Katch-McArdle Calculator

We hope that you were able to find answers to all your questions and wish you a great journey with YAZIO. Should you have any more questions, please feel free to contact our support team and submit your request here.