Calculating Lean Body Mass

When it comes to understanding our bodies, it's vital to grasp the concept of lean body mass (LBM). Often, people misunderstand or confuse the term, but it's a critical factor in our overall health and well-being. Let's dive deeper into what lean body mass is and why it's so important.

Understanding Lean Body Mass

Lean body mass (LBM) refers to everything that remains in the body after subtracting storage fat or adipose tissue. It's a crucial anthropometric parameter that is distinct from your ideal weight. However, it's not to be confused with another related term, fat-free mass (FFM), which is everything left in the body after removing all lipid components, including essential fat.

The essential fat, which safeguards internal organs, constitutes bone marrow, mammary glands, and is present in various tissues, is crucial for an individual's health. It makes up approximately 3% of the male body mass and 12% of the female body mass.

The Composition of Lean Body Mass

Lean body mass is composed of bones, teeth, muscles, internal organs, connective tissue, and essential fat. The differentiation between lean body mass and fat-free mass is critical because essential fat is vital for an individual's health.

Fat mass (FM), on the other hand, represents the total amount of lipids extractable from the human body, including both primary and storage fat. A fat mass of less than 3% in men and 12% in women is not conducive to good health, and in extreme cases, it can be life-threatening.

Measuring Lean Body Mass

The determination of lean body mass can be conducted via various methodologies, each differing in practicality, precision, and cost. These methods include plicometry, bioimpedance measurement, body circumferences, Dexa, creatinine, magnetic resonance imaging, CT scan, K40, and ultrasound.

However, a simple and immediate method involves calculating lean body mass based on an individual's height and weight using different formulas.

The Boer formula

For men: LBM = (0.407 × Weight in Kg) + (0.267 × Height in cm) − 19.2

For women: LBM = (0.252 × Weight in Kg) + (0.473 × Height in cm) − 48.3

The Hume formula

For men: LBM = (0.32810 × Weight in Kg) + (0.33929 × Height in cm) − 29.5336

For women: LBM = (0.29569 × Weight in Kg) + (0.41813 × Height in cm) − 43.2933

These equations are approximations and are useful for obtaining an estimate of lean mass in sedentary individuals. However, they are not reliable for athletes as their value is influenced by muscle mass and bone mass.

The Importance of Lean Body Mass

Accurately calculated lean body mass provides excellent insights into basal metabolism, significantly better than those obtained based on the individual's height. The basal metabolic rate, according to Katch and McArdle formula, is equal to: 370 +(21.6 × LBM)

The basal metabolic rate is directly proportional to a subject's lean mass. As its value is mostly influenced by muscle tissue, the more muscle we have, the more calories we burn throughout the day, regardless of age, thyroid function, and physical activity level.

Muscle is a living tissue, continuously renewing, and with metabolic demands significantly higher than adipose tissue. Therefore, to lose weight, it's advisable to increase lean mass by following an appropriate diet and a regular exercise program.

In conclusion, understanding and maintaining your lean body mass is crucial for overall health and well-being. It not only helps in weight management but also contributes to the body's metabolic rate and energy consumption. So, pay attention to your LBM, and remember, it's not just about losing weight, but about maintaining a healthy body composition.