Body mass index (BMI), body measurements and body composition – why Yazen uses multiple measures

1. How Yazen uses BMI in a health assessment

‍BMI serves as an initial part of the health assessment by providing an overall indication of weight status and potential health risks. At the same time, the measure has limitations and does not reflect the full individual health situation. At Yazen, BMI is therefore used as a screening tool and is complemented with additional clinical data, such as blood tests, waist circumference and other relevant body measurements. This enables a more nuanced medical assessment and the development of an individualised treatment plan.

2. Body measurement analysis

‍How fat is distributed in the body plays a major role in health. Fat stored deep within the abdomen, around the organs – known as visceral abdominal fat – is linked to insulin resistance, inflammation and hormonal changes that affect metabolism. This increases the risk of metabolic diseases such as type 2 diabetes, fatty liver disease and cardiovascular disease.

When body measurements are combined with BMI, a more nuanced picture of health emerges. By monitoring waist, hip, height and neck measurements, proportions and ratios can be calculated, making it possible to:

• estimate and track body fat percentage
• estimate fat distribution and metabolic risk
• tailor treatment strategies based on individual measurements and risk profile

3. Body composition via bioelectrical impedance analysis (BIA)

‍In collaboration with Withings, Yazen offers the option to order a bioimpedance scale that can be connected to the Yazen app. In addition to body weight, this scale can provide information about body composition, such as body fat, muscle mass and visceral fat. The measurements are synchronised with the Yazen app, allowing changes in weight, body fat percentage and muscle mass to be tracked over time. This information is also shared with the treatment team. This enables long-term monitoring of body composition and allows lifestyle interventions to be adjusted to achieve a healthy balance between muscle mass and body fat.

How BMI works

BMI (Body Mass Index) is a measure that shows the relationship between your weight and height. It can provide an initial indication of health risks and help you understand how different factors affect your wellbeing. You can calculate your BMI using a simple formula or digital tools, such as Yazen’s BMI calculator.

At a population level, BMI has been shown to have a strong association with increased risk of diseases such as cardiovascular disease, type 2 diabetes, high blood pressure and certain cancers. However, for the individual patient, BMI does not provide a clear picture of how excess body fat affects health. People with the same BMI can therefore have very different risk profiles: some may have complications and weight-related conditions, while others may not.

Individuals with similar BMI values can also differ in the amount and distribution of body fat, which affects health outcomes in different ways. Due to the complex and heterogeneous nature of obesity, further clinical assessment is therefore required to determine the extent to which excess body fat affects an individual’s health.

BMI categories – understanding your result

When you calculate your BMI, the result falls into a specific category. Your BMI category provides information about potential health risks and can be used as guidance to understand your current health status. Each category is associated with different levels of health risk.

It is important to be aware that BMI was developed based on Western populations and does not fit all population groups equally well. Research shows, for example, that people of Asian descent may experience increased metabolic risk at lower BMI levels (e.g. BMI ≥ 23 = increased risk, BMI ≥ 27.5 = high risk). In addition, BMI may underestimate risk in older adults, as muscle mass often decreases with age.

For this reason, BMI should always be considered alongside other factors such as body measurements, other health markers, lifestyle and how you feel overall. The purpose of interpreting BMI is to provide an initial indication of overall health status. The result can be used as a basis for assessing whether further medical investigation or lifestyle support is needed, and as guidance when working towards a healthy weight. In this way, BMI can contribute to promoting long-term health and wellbeing.

Underweight – BMI below 18.5

‍A low BMI often indicates that the body may be lacking adequate nutrition and that there is an increased risk of health problems related to underweight. It may be a sign that the body is not receiving enough energy or nutrients, which can affect energy levels, immune function and muscle mass.

Healthy weight – BMI 18.5–24.9

‍This category indicates a healthy weight, where the risk of weight-related diseases is generally lowest. The focus is on maintaining stable habits that support long-term health: regular physical activity, a healthy and varied diet, and adequate recovery.

Overweight – BMI 25–29.9

‍In this range, the risk of future health problems may increase slightly, particularly from a BMI of around 27 and above. Many people in this category feel well but may benefit from reviewing their habits to reduce the risk of conditions such as type 2 diabetes and elevated blood lipids. Untreated overweight can also progress to obesity, further increasing disease risk.
Small changes can make a big difference. Often, adjustments to diet, physical activity and daily routines are sufficient, ideally with support from healthcare professionals when needed.

Obesity class 1 – BMI 30–34.9

‍A BMI above 30 is classified as obesity and is associated with an increased risk of several obesity-related conditions, such as elevated blood lipids, and can affect energy levels, blood pressure and blood sugar regulation. Many people find that a structured programme works best for obesity treatment, with guidance from healthcare professionals and support tailored to individual needs. Medical weight-loss treatment may be an option for some and should be monitored regularly by a doctor.

Obesity class 2–3 – BMI ≥ 35

‍At higher BMI levels – particularly above 35, classified as severe obesity – the risk of obesity-related conditions increases further, including elevated blood lipids, type 2 diabetes and cardiovascular disease. In some cases, more extensive support may be required, such as bariatric surgery, if other treatment methods do not provide sufficient results.

Body measurements

The distribution of body fat is crucial for health. When more fat accumulates deep within the abdomen, around the organs, the risk of several diseases increases. This visceral abdominal fat is linked to insulin resistance, inflammation and hormonal changes that regulate metabolism. Together, these factors can lead to metabolic diseases such as type 2 diabetes, fatty liver disease and cardiovascular disease.

Research shows that several body measurements and ratios often predict disease risk and premature mortality better than BMI alone. For example, a larger waist circumference or a high waist-to-height ratio is strongly associated with increased risk of type 2 diabetes, cardiovascular disease and other metabolic disorders.

Body composition via BIA

Bioelectrical impedance analysis (BIA) measures how easily an electrical current passes through the body via electrodes on the skin. Because different tissues conduct electricity differently, the method can estimate body composition, such as fat mass and muscle mass.

A healthy body composition involves a balance between muscle mass and body fat, as well as where fat is stored in the body. This is particularly important because excessive body fat, especially visceral abdominal fat, increases the risk of type 2 diabetes, high blood pressure and cardiovascular disease. At the same time, optimal muscle mass is essential for proper bodily function, maintaining metabolism and reducing injury risk.

During weight loss, both fat and muscle mass are usually lost. Because muscle mass plays such a vital role in overall health and long-term weight stability, it is important to minimise muscle loss. Regular strength training combined with adequate protein intake are key factors in reducing muscle loss during weight loss.

By measuring body composition, you gain a clearer picture of what is happening in your body during lifestyle changes. It also helps you set appropriate goals, whether you want to lose weight, increase muscle mass or improve your health in other ways. Weight and body composition can vary from day to day due to factors such as physical activity and dietary intake, which is why trends over repeated measurements are more informative than single measurements. To obtain comparable results, it is important to weigh yourself under similar conditions each time.

Regular measurements and clear tracking of results can help maintain motivation and focus throughout your health journey. By regularly evaluating how your diet and exercise plan affect your weight, body fat percentage and muscle mass, you can more easily adjust your treatment in the desired direction.

A long-term health journey

BMI is only a starting point. What matters most is what you need to feel well and strengthen your long-term health. For some, the goal may be to maintain a new weight, while others aim for weight loss to achieve a healthy weight and improve wellbeing in a sustainable way.

Your health is unique, and different life situations require different solutions. Strategies for achieving and maintaining a healthy weight vary depending on age, lifestyle and individual circumstances. That is why Yazen works to tailor treatment specifically to you.

The long-term strategy for maintaining healthy habits is just as important as the initial weight change. Through our professional team, you receive support to develop sustainable methods that fit your life situation. People of different ages and with different needs require different approaches, and a good healthcare team takes these individual needs into account.

Professional support for weight-related health

You do not have to make the journey alone. At Yazen, you gain access to a team of healthcare professionals who help you find strategies that work for your everyday life, both via our digital platform and through personal contact. You can also receive support from various specialists. Your Yazen team includes:

• Doctors, who assess health risks and help identify appropriate treatment options
• Dietitians, who support you with personalised nutritional guidance
• Personal trainers, who help tailor physical activity to improve your health
• Psychologists, who support you with thoughts and emotions related to body image, weight and food
• YazenCoach, your main point of contact, who supports you throughout your treatment and guides you to the right expert in nutrition, mental health or physical activity when needed

At Yazen, we combine evidence-based methods with care and personalised support – to help you strengthen your health on your own terms.