Understanding Body Composition: How to Read Muscle Mass, Body Fat & Visceral Fat

The most important points in 3 takeaways

• Two people with the same body weight can have completely different body compositions.
• Visceral fat is the metabolically active fat surrounding your organs and is closely linked to cardiovascular risk.
• Muscle mass supports your metabolic capacity – low muscle mass has been associated with higher mortality in scientific studies.

This article explains the most important body composition metrics, what they mean for your health, and how to interpret them – no degree in statistics required.

What is body composition?

Your body is made up – broadly speaking – of fat, muscle, water, and bone. Body composition describes how your body weight is distributed across these different components.

This explains a common observation: Two people who are the same height and weigh exactly the same can look completely different – and have very different health profiles. One may have more muscle, the other more body fat. On the scale, they are identical. Beneath the surface, they are not.

Why body composition tells you more than the scale – and BMI

Body weight and BMI do not distinguish between fat and muscle, nor do they tell you where fat is stored. Yet this is exactly what matters:

Where fat is stored: Fat surrounding the organs (visceral fat) is metabolically active and poses a greater health risk than subcutaneous fat.

How much muscle you have: Muscle is your body's metabolic engine. It supports metabolic health, strength, and physical function – especially as you age.

That is why body composition provides a more accurate picture of your health than a single number on the scale.

The most important metrics – and how to interpret them

Skeletal muscle mass

Muscles use energy, help regulate blood sugar, and support metabolic flexibility. Low muscle mass is not simply a matter of appearance: A meta-analysis of 16 studies involving more than 81,000 participants found that low skeletal muscle mass was associated with an approximately 57% higher risk of all-cause mortality (PLOS One, 2023). More muscle is therefore an important part of preventive health.

Body fat percentage

Body fat percentage shows how much of your body weight consists of fat. It is more informative than BMI because it distinguishes fat from muscle. Interpretation should always take sex, age, and the measurement method into account. In most cases, changes over time are more meaningful than a single measurement.

Visceral fat

Visceral fat is the fat stored around your internal organs. It is metabolically active tissue that releases free fatty acids and inflammatory signalling molecules, contributing to metabolic dysfunction. Systematic reviews have associated higher levels of visceral fat with a less favourable cardiometabolic profile and increased mortality (Frontiers in Endocrinology, 2022).

Reading the muscle-fat analysis: understanding the bar chart

Many body composition analyses display three bars stacked vertically: body weight, skeletal muscle mass, and body fat mass. A simple rule of thumb is that a longer muscle bar than fat bar (with both remaining proportional to your overall weight) is generally a positive sign. A shorter muscle bar combined with a longer fat bar suggests there may be room for improvement. The most important aspect is the overall pattern – and how it changes over time.

What are “good” values?

There is no single ideal number. Healthy ranges vary depending on age, sex, fitness level, and the measurement method used. Two principles are more helpful than any reference table:

Trends matter more than single measurements. If your body fat is decreasing while your muscle mass stays stable or increases, you’re moving in the right direction—regardless of where you started.

Balance matters more than individual numbers. The ratio of muscle to fat (combined with low visceral fat) is more meaningful than any single percentage.

The best way to understand what your specific results mean is to discuss them with a healthcare professional.

What you can do

The two most effective strategies are:

Strength training builds and preserves muscle mass (aim for 2–3 sessions per week for meaningful results).

Getting enough protein helps preserve muscle, especially during weight loss.

Zone 2 exercise (60–70% of your maximum heart rate) is one of the most effective ways to reduce visceral fat.

If you’re trying to lose weight, preserving muscle mass is essential. We explain why in detail in our article on muscle and weight loss.

Why trends matter more than a single measurement

A single measurement is like a photograph. What you really want is the movie: Is your body composition moving in the right direction?

That’s why care doesn’t measure body composition just once. As part of your treatment, it is measured monthly. This allows you to see whether you’re losing fat while maintaining muscle mass—and adjust your plan accordingly.

What a care body composition analysis measures

A care body composition analysis measures far more than your weight and body fat percentage. In just a few minutes, it provides a comprehensive overview across four key areas:

Body Score – an overall score (0–100) that combines your measurements into a single assessment and helps you track your progress over time.

Muscle & Metabolism – Skeletal Muscle Index (SMI), Fat-Free Mass Index (FFMI), and Basal Metabolic Rate (BMR): showing how much energy your body burns at rest.

Muscle & Fat Mass – your body weight, skeletal muscle mass, and body fat mass in kilograms.

Fat Analysis – body fat percentage, BMI, waist-to-height ratio, waist circumference, and visceral fat—the metabolically active fat surrounding your organs.

This allows you to see not only whether things are changing, but exactly what is changing—muscle, fat, metabolism, and visceral fat are all assessed separately. Your results are then interpreted by a physician to create a personalised plan, rather than leaving you with a collection of numbers.

Know your numbers. A muscle and fat analysis is part of the care Full Body Check-up, together with blood tests and blood pressure measurements—all reviewed by a physician. That way, you’ll know where you stand instead of guessing.

→ Discover the care Full Body Check-up

Already receiving treatment with care? Your monthly muscle and fat analysis, along with your progress over time, is available in the App.

In brief

Your body composition tells you far more about your health than your weight or BMI. It shows how much muscle supports your body, how much body fat you have, and how much of that fat is stored as visceral fat around your organs. Focus less on individual numbers and more on the overall balance and how your results change over time. And remember the two habits that make the biggest difference: strength training and getting enough protein.

Frequently Asked Questions

What is the difference between body fat percentage and BMI? BMI simply compares your weight to your height and does not distinguish between fat and muscle. Body fat percentage shows directly how much of your body weight is made up of fat, making it a more informative measure.

Why is visceral fat more dangerous than other types of fat? Because it is metabolically active. It releases free fatty acids and inflammatory signalling molecules and is associated with a higher risk of cardiovascular and metabolic disease.

What is a healthy body fat percentage? That depends on your sex, age, and the measurement method used. There is no single “healthy” number. The trend over time and the balance between muscle and fat are far more meaningful. Your results are best interpreted by a healthcare professional.

How often should you measure your body composition? A single measurement provides only limited information—the trend over time is what matters. As part of an ongoing treatment plan, measuring body composition once a month is a practical way to track your progress.

Medical disclaimer

This article is intended for general information and health education only. It does not replace personalised medical advice, diagnosis, or treatment. The meaning of your individual results should always be interpreted by a qualified healthcare professional. If you have any health concerns or symptoms, please consult a doctor.