Lean Body Mass: The Basics & The Genetics
Table of Contents
Understanding the concept of lean body mass and its influencing factors is pivotal for anyone looking to improve their fitness level or body composition. This article will delve into what lean body mass is, how to calculate and increase it, and the role of genetics and non-genetic factors in determining it.
What is Lean Body Mass?
Lean body mass (LBM) refers to the weight of everything in your body, excluding fat. This includes your bones, organs, skin, blood, and most importantly, your muscle mass. It’s a critical factor in determining your overall physical health, fitness level, and metabolic rate.
How to Calculate Lean Body Mass?
Lean body mass can be calculated using the following formula:
Lean Body Mass = Total Body Weight – Body Fat Weight
To use this formula, you first need to know your total body weight and your body fat weight. Your body fat weight can be calculated by multiplying your total body weight by your body fat percentage.
How to Find Lean Body Mass?
There are several methods to find out your lean body mass. The simplest method is to use body composition scales that give you a breakdown of fat mass, muscle mass, and sometimes bone mass and water weight.
More accurate methods include Dual-energy X-ray absorptiometry (DEXA), bioelectrical impedance analysis (BIA), and hydrostatic weighing. These methods should be administered by a trained professional.
How to Increase Lean Body Mass?
Increasing lean body mass predominantly involves gaining muscle. Here are some strategies:
- Resistance Training: Regular resistance training is key. This includes weight lifting, bodyweight exercises, and resistance band exercises.
- Protein Intake: Consuming sufficient protein is crucial as it provides the building blocks for muscle growth.
- Caloric Surplus: Eating slightly more calories than your body burns can support muscle growth.
- Adequate Rest: Giving your body time to recover and grow after workouts is essential.
Genes that Influence Lean Body Mass
Lean body mass, which predominantly consists of muscle mass, is significantly influenced by your genetic makeup. Here are some genes that play a crucial role:
ACTN3
The ACTN3 gene, also known as the ‘sprint gene’, codes for a protein found in fast-twitch muscle fibers, which are responsible for power and speed. The R577X polymorphism in the ACTN3 gene (rs1815739) results in two common variants: R and X.
Individuals with the RR genotype produce alpha-actinin-3 and might have a higher proportion of fast-twitch muscle fibers, which could potentially lead to greater muscle mass. Those with the RX genotype have an intermediate amount, while those with the XX genotype cannot produce alpha-actinin-3. The XX genotype is thought to be more beneficial for endurance activities rather than power-based ones.
MSTN
The MSTN gene codes for myostatin, a protein that limits muscle growth to prevent muscles from becoming too large. This process, known as negative regulation, is important for maintaining control over muscle size and preventing excessive growth.
However, variations in this gene can influence its function. For instance, the rs1805086 (K153R) variant of the MSTN gene results in a change in the myostatin protein that might reduce its activity. Individuals with this variant may have the potential for increased muscle growth and thus higher lean body mass.
VDR
The VDR gene provides the instructions for making vitamin D receptors in the body. These receptors bind with vitamin D to activate certain genes, influencing a variety of biological processes including muscle function.
Specifically, certain variants of the VDR gene have been associated with muscle strength and mass. For instance, the FokI polymorphism (rs2228570) results in two variants: F and f. The FF genotype has been associated with increased muscle strength compared to Ff and ff genotypes.
IGF1
Insulin-like growth factor 1 (IGF1) is a hormone that plays a crucial role in muscle growth and repair. Variants in the IGF1 gene can influence the levels of IGF1 in the body, which may in turn impact muscle mass. For example, the rs35767 variant of IGF1 has been associated with IGF1 levels, and the C allele has been linked with higher levels of circulating IGF1 and potentially greater muscle mass.
It’s important to note that while these genes can influence lean body mass, they do not work in isolation and the overall impact will depend on the interplay of many genes as well as environmental factors.
SNP Table
| Gene | SNP | Description |
|---|---|---|
| ACTN3 | rs1815739 | The R allele is associated with a higher proportion of fast-twitch muscle fibers and potentially greater muscle mass. |
| MSTN | rs1805086 | The G allele might result in reduced myostatin activity, potentially facilitating greater muscle mass. |
| VDR | rs2228570 (FokI) | The F allele has been linked to greater muscle strength. |
Non-Genetic Factors that Affect Lean Body Mass
While genetics play a crucial role, various non-genetic factors significantly affect lean body mass. Let’s examine some of these factors:
Diet
Diet plays a pivotal role in influencing lean body mass, particularly protein intake. Proteins provide the necessary amino acids required for muscle repair and growth after exercise. Consuming sufficient protein, especially in close proximity to resistance training, can support muscle synthesis and thus increase lean body mass.
Exercise
Physical activity, specifically resistance and strength training exercises, is a key non-genetic factor influencing lean body mass. Such exercises trigger muscle protein synthesis, leading to muscle growth and increased lean body mass. Consistency and progressive overload, or gradually increasing the intensity of workouts, are vital for continual muscle growth.
Hormonal Balance
Hormones like testosterone, growth hormone, and insulin-like growth factor play significant roles in muscle growth and recovery. Any imbalances in these hormones can impact lean body mass. For instance, low testosterone levels can hinder muscle growth and recovery.
Age
As we age, we naturally lose muscle mass in a process called sarcopenia. This process can start as early as the age of 30 and accelerates after 60. Resistance training and protein-rich diets can help counteract this muscle loss.
Sleep
Sleep is a crucial recovery time for the body. During sleep, growth hormone is released, which aids in muscle recovery and growth. Lack of sleep can hinder this process and negatively impact lean body mass.
Stress
Chronic stress can negatively affect lean body mass. It can disrupt hormonal balance and negatively impact muscle recovery and growth. Techniques to manage stress, such as meditation, yoga, and other relaxation exercises, can be beneficial.
How to Improve Lean Body Mass Based on Your Genes?
Your genetic predispositions can offer valuable insights that can be used to personalize strategies for improving lean body mass. Here are some ways you can leverage this genetic information:
Understand Your Genetic Profile
The first step to tailoring your approach based on your genes is to understand your genetic profile. Various genetic testing services can provide insights into how your body might respond to certain types of exercise and diet, helping you customize your strategy accordingly.
For instance, if you have the RR genotype in the ACTN3 gene, which is associated with an increased proportion of fast-twitch muscle fibers and potentially greater muscle mass, you might focus more on power and strength-based resistance training.
Customize Your Exercise Regimen
Once you have a clear understanding of your genetic profile, you can customize your exercise regimen to align with your genetic predispositions. If you have a genetic variant that suggests you may respond well to resistance training, such as certain ACTN3 or MSTN variants, incorporating more strength training exercises into your workout could help you increase your lean body mass.
Adjust Your Nutrition
Your genetics can also provide insight into how you should adjust your diet to effectively increase lean body mass. For example, certain genetic variants can influence how your body metabolizes protein. If you have a variant that suggests you might require more protein to effectively build muscle, increasing your protein intake could help you gain lean body mass.
Consider Hormonal Influences
Certain genetic variants can influence hormone levels, which in turn can affect lean body mass. For example, variations in the SHBG gene can affect testosterone levels, influencing muscle growth and recovery. Understanding these genetic influences can help tailor strategies to maximize lean body mass gains.
Remember the Role of Lifestyle Factors
Regardless of genetic predispositions, lifestyle factors like sleep, stress management, and consistency in training and diet play a significant role in improving lean body mass. For example, regardless of whether your genes suggest you need more or less sleep for optimal recovery, prioritizing quality sleep is essential for muscle recovery and growth.
Working with a fitness professional who understands genetic testing can be beneficial in translating your genetic insights into a practical and effective plan for improving lean body mass.
Summary
What is lean body mass? Lean body mass refers to the weight of everything in your body, excluding fat. It includes bones, organs, skin, blood, and muscle mass.
How can I increase my lean body mass? To increase lean body mass, engage in regular resistance training, consume a protein-rich diet, maintain a slight caloric surplus, and ensure adequate rest and recovery.
How do genes influence lean body mass? Certain genes, like ACTN3, MSTN, and VDR, can influence muscle fiber type, muscle growth regulation, and muscle function, respectively, potentially affecting lean body mass.
References
- Antonio J, Ellerbroek A, Silver T, et al. The effects of a high protein diet on indices of health and body composition – a crossover trial in resistance-trained men. J Int Soc Sports Nutr. 2016;13:3.
- Pickering C, Kiely J. ACTN3: More than Just a Gene for Speed. Front Physiol. 2017;8:1080.
- Santiago C, Ruiz JR, Muniesa CA, et al. Does the polygenic profile determine the potential for becoming a world-class athlete? Insights from the sport of rowing. Scand J Med Sci Sports. 2010;20(1):e188-e194.
- Ahmetov II, Donnikov AE, Trofimov DY. The Actn3 genotype is associated with the testosterone levels of athletes. Biol Sport. 2014;31(2):105-108.
- Bouchard C. Overcoming barriers to progress in exercise genomics. Exerc Sport Sci Rev. 2011;39(4):212-217.
Written By
Share this article
