Lean body mass is the total weight of your body minus all the weight due to your fat mass. In other words, it calculates the weight of all the components of your body except for fat mass, including muscles, bones, skin, organs, blood, and other tissues [1]. Calculating your lean body weight can be beneficial in several ways, especially for fitness-oriented individuals. You can easily use our LBM calculator to get an accurate estimate.
What’s My Lean Body Mass?
Usually, you would need to know your current body fat percentage to calculate your LBM. But with the algorithm, you can do so by inputting just your weight and height. The value will also change depending on whether you are younger or older than 14 years of age.
Knowing your LBM can help you on several fronts. For example, if you are trying to lose weight, you can track your LBM to see how much muscle you are losing with time. If you are losing more muscle mass than fat mass, it is an indication that there is a flaw in your diet/training program.
Similarly, you can also assess the efficiency of your muscle-building programs by tracking your LBM. The values can be used as a benchmark of progress and allow you to adjust your macronutrient intake, exercise routines, and other parameters accordingly.
Parameters like LBM are more efficient compared to basic fitness metrics like BMI because they take into account an individual’s body composition[2]. To get a good perspective of your current health level, it’s imperative that you calculate lean body mass in addition to other basic fitness trackers.
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What is Lean Body Mass?
Lean body mass is the total weight of your body minus the weight of your body fat.
Apart from muscle, your LBM also includes the weight of your bones, water inside the body, connective tissue, and even some stored-up glycogen. It also includes essential fat that is necessary for normal physiological functions, which is found in organs, bone marrow, and nervous tissues.
In addition to being a helpful fitness indicator, knowing your LBM is also essential for some physiological functions. These include mobility, metabolism, and overall health [3]. As such, maintaining healthy levels of lean body mass should be an end goal for all individuals.
For men, a healthy LBM percentage typically ranges from 75-90% of total body weight, while for women, it’s around 68-80%, reflecting essential fat differences between sexes. Maintaining a healthy LBM supports overall health, physical performance, and can reduce the risk of chronic diseases. The figure varies due to changes in sex and age. Generally, LBM figures less than 75% in men and 68% in women may be an indication of impending health concerns.
How to Calculate Lean Body Mass?
There are many formulas for calculating one’s lean body mass. However, they might seem very complicated and lengthy.
The better and more convenient way of calculating your LBM would be to use our lean body mass calculator. Using that, you can simply input parameters like your weight, height, and body fat percentage to get a precise estimate of your LBM.
Lean Body Mass Formulas
There are many equations that can help us calculate our respective lean body masses. Each of them varies based on different parameters, including the sex of the individual.
For our calculator, we use a combination of equations – including the Boer formula, the James formula, and the Hume formula to yield the most accurate results. We also use the Peters Formula for calculating the LBM of children aged 14 years or under.
Let’s have a look at some of the most popular equations. The equations listed below work only for measurements given in metric units.
The Boer Formula:
The Boer Formula is the most popular in the modern times. It is given by:
LBM for Males = 0.407 * Weight + 0.267 * Height – 19.2
LBM for Females = 0.252 Weight + 0.473 Height – 48.3
The James Formula
The James Formula is also relatively popular due to its accuracy. It is given by:
LBM for Males = 1.1 * Weight – 128 (Weight/Height)2
LBM for Females = 1.07 * Weight – 148 (Weight/Height)2
The Hume Formula:
The Hume Formula is slightly less popular than the other two. It is given by:
LBM for Males = 0.32810 * Weight + 0.33929 * Height – 29.5336
LBM for Females = 0.29569 * Weight + 0.41813 * Height – 43.2933
The Peters Formula
The Peters Formula was developed exclusively to calculate the lean body mass of children aged 14 years or younger.
Here, the equation computes an estimate of the LBM based on the Extracellular Volume (ECV) of the individual.
It is given by:
Estimated ECV = 0.0215 * Weight0.6469 * Height0.7236
LBM = 3.8 * Estimated ECV
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Is Lean Body Mass the Same as Skeletal Muscle Mass?
No, Lean Body Mass and Skeletal Mass are entirely different from each other. The former is concerned with calculating the weight of the body minus the body fat. On the other hand, Skeletal Mass weighs the pure muscle present in the body.
While the two terms are used interchangeably, there are many distinctions that differentiate the two metrics.
What is the Difference Between Lean Body Mass and Skeletal Muscle Mass?
People often confuse Lean Body Mass and Skeletal Muscle Mass because they think that Lean Body Mass measures an individual’s pure muscle mass. However, that is not true at all.
Lean Body Mass refers to the total weight of the body – including components like organs, skin, blood, bones, water, and more – minus the body fat. Skeletal Muscle Mass, on the other hand, only calculates the weight of the muscle mass present in the body [4].
Another major difference between the two is that an increase in Skeletal Muscle Mass will result in a definite increase in Lean Body Mass. However, it’s not certain that Skeletal Muscle Mass may increase if Lean Body Mass is increasing [5]. This is because an increase in LBM can be due to two factors – either SMM is increasing or total body water is increasing.
Basically, we can say that our Skeletal Muscle Mass is nothing but a component of our overall Lean Body Mass.
Is Lean Body Mass the Same as Fat Free Mass?
No, Lean Body Mass and Fat-Free Mass are not the same. While these two terms are used interchangeably, they are very different from each other.
We have said before that LBM is nothing but the total weight of all the components minus body fat. However, it does take into account some essential fats.
Fat-free mass, on the other hand, is different as it does not take into account any kind of fat whatsoever.
What is the Difference Between Lean Body Mass and Fat Free Mass?
While lean body mass includes the weight of all components except body fat, it does count some essential fat present in the internal organs, bone marrow, and nervous tissues for measurement. That is why it is not the same as fat-free mass, which excludes all kinds of fat altogether.
In LBM, the essential fats present in the organs, the central nervous system, and bone marrow are measured. Only the nonessential or storage fat tissues (subcutaneous fat) present underneath the skin and around the internal organs are excluded.
In other words, fat-free mass is simply the difference between an individual’s lean body mass and essential fats present in the body. Generally, this constitutes a difference of around 2-3% in men and 5-12% in women.
Final Words
An individual’s lean body mass is an important indicator of their fitness level. It represents the overall body composition minus all the nonessential fat tissues.
With our LBM calculator, you can get an accurate measurement even if you don’t know your body fat percentage. By measuring this value, you can track your weight loss or muscle growth journey efficiently and ensure that your fitness/diet plans are up to date.
References
- Roubenoff, R., & Kehayias, J. J. (2009). The meaning and measurement of lean body mass. Nutrition Reviews, 49(6), 163–175. https://doi.org/10.1111/j.1753-4887.1991.tb03013.x
- Lee, D. H., Keum, N., Hu, F. B., Orav, E. J., Rimm, E. B., Willett, W. C., & Giovannucci, E. L. (2018). Predicted lean body mass, fat mass, and all cause and cause specific mortality in men: Prospective US cohort study. BMJ, k2575. https://doi.org/10.1136/bmj.k2575
- Cheung, C., Lee, G. K., Au, P. C., Li, G. H., Chan, M., Li, H., Cheung, B., Wong, I. C. K., Lee, V., Mok, J., Yip, B., Cheng, K. K. Y., & Wu, C. (2021). Systematic review and meta-analysis of lean mass and mortality: Rationale and study description. Osteoporosis and Sarcopenia, 7, S3–S12. https://doi.org/10.1016/j.afos.2021.01.001
- Pomeroy, E., Macintosh, A., Wells, J. C., Cole, T. J., & Stock, J. T. (2018). Relationship between body mass, lean mass, fat mass, and limb bone cross‐sectional geometry: Implications for estimating body mass and physique from the skeleton. American Journal of Physical Anthropology, 166(1), 56-69. https://doi.org/10.1002/ajpa.23398
- Kim, S. R., Lee, G., Choi, S., Oh, Y. H., Son, J. S., Park, M., & Park, S. M. (2022). Changes in predicted lean body mass, appendicular skeletal muscle mass, and body fat mass and cardiovascular disease. Journal of Cachexia, Sarcopenia and Muscle, 13(2), 1113-1123. https://doi.org/10.1002/jcsm.12962