Why know the exact composition of your body
Regular bathroom scales show only one number - your total weight. But this figure does not give a real idea of physical fitness and health. Two people can weigh the same, say 80 kilograms, but look completely different. One will have a toned, athletic build, while the other will be noticeably overweight.
The secret lies in the ratio of fabrics. Muscle is much denser than fat. One kilogram of muscle tissue takes up significantly less volume than one kilogram of fat. Therefore, when losing weight or exercising properly, it is important not to watch the scale, but to ensure that the fat goes away and the muscles remain in place.
⚡ Оценка мышечной массы (по формуле Бура)
Lean mass and muscle mass: what is the difference
When making calculations, people often confuse two important medical terms. To correctly evaluate the results of calculators and instruments, you need to understand the difference between them:
- Lean Body Mass (LBM) This is the weight of your entire body, from which the weight of fat has been completely subtracted. Dry mass includes your bones, internal organs, all the fluid in the body, skin and, of course, muscles.
- Skeletal muscle mass (SMM) This is the weight solely of your muscles, which are attached to your bones and are responsible for movement. On average, pure muscle makes up about 50% of the total dry body mass.
Boer formula: the mathematics of body composition
The most popular algorithm for independent calculations without medical devices is the formula of the South African scientist Peter Boer (Boer formula). It was developed based on extensive research and uses only two parameters: a person’s height and weight.
Due to genetic and hormonal differences, the calculation algorithms for men and women are different.
Formula for men:
Dry mass = (0.407 × Weight in kg) + (0.267 × Height in cm) − 19.2
Formula for women:
Dry mass = (0.252 × Weight in kg) + (0.473 × Height in cm) − 48.3
To find out the approximate weight of skeletal muscles, the resulting dry mass result must be divided in half.
Medical and hardware measurement methods
If mathematical formulas provide only a rough guide, modern technologies allow us to look inside the body and obtain data with an accuracy of up to a gram. Today there are three main methods of objective assessment:
- Bioimpedance analysis (Smart scales). This method is used in fitness clubs and home smart scales. The device passes a very weak, imperceptible electrical impulse through the body. Different tissues resist current in different ways: water and muscles conduct it well, but fat conducts it poorly. Based on this resistance, the processor calculates the exact percentage of each tissue.
- Caliperometry. This is a manual method in which a specialist uses a special device - a caliper (similar to a caliper). They capture folds of skin at several points on the body (on the stomach, back, hips) and measure their thickness. Then the data is inserted into special tables.
- DEXA scanning. The most accurate and expensive medical method. This is a low-dose X-ray test that not only shows the amount of muscle, fat and bone, but also categorizes this data into specific parts of the body (for example, how much muscle is on the right arm and how much on the left).
Healthy norms: what numbers to focus on
The percentage of muscle tissue depends on age, gender and fitness level. The male body naturally produces more testosterone, so the muscular frame in men is always heavier and more voluminous.
| Level of preparation | Norm for men | Normal for women |
|---|---|---|
| Low (sedentary image) | Less than 33% | Less than 24% |
| Medium (healthy norm) | 33% - 39% | 24% - 30% |
| High (regular sports) | 40% - 44% | 31% - 35% |
| Professional athletes | More than 44% | More than 35% |
Why body mass index (BMI) is outdated
Doctors have long used Body Mass Index to diagnose obesity. This index simply divides a person's weight by their height squared. However, today this method is considered inaccurate for assessing health.
BMI does not take body composition into account at all. If a professional weightlifter steps on the scale, his BMI may show he is severely obese, even though he has almost no body fat—all the excess weight comes from heavy, trained muscles. That is why the focus in modern dietetics and fitness has shifted from simple weighing to monitoring the percentage of muscle and fat tissue.