Striving to keep our body healthy as we age can be a challenge! One of the toughest challenges is maintaining a healthy body composition, or the percentages of lean tissue and fat mass. Starting in our mid-forties, we begin to lose muscle mass and progressively accumulate fat mass. On average, between the ages of 40-60, a person gains about 1 pound of fat per year and loses a 1/2 pound of muscle. By age 75, 50% of your muscle mass can vanish! (1) Beyond the loss of strength that occurs with reduced muscle mass, a loss in lean tissue affects our health in many ways and even puts us at greater risk for disease. Read on to learn how lean body mass is critical for building strong bones as well as maintaining a healthy, well-functioning body as we age.
What is lean body mass? Lean body mass consists of your bones, ligaments, tendons, internal organs, muscles and water…everything in your body that’s not fat. Because lean body mass includes components whose weight cannot be easily changed, such as the weight of your internal organs, the loss or gain of skeletal muscle mass is the primary reason for change in lean body mass. Therefore, lean body mass, lean tissue mass and muscle mass are terms that are frequently used interchangeably.
5 Reasons why Lean Body Mass Benefits your Health as you Age
Lean Body Mass Combats Obesity:
Lean body mass is associated with your basal metabolic rate (BMR), or the amount of calories you burn at rest. Muscles, even at rest, require energy in the form of calories while fat cells do not. So the greater amount of lean muscle tissue you have, the more calories you burn throughout the day decreasing the likelihood of excessive fat accumulation and obesity. Obesity is a contributing factor to many chronic diseases such as chronic systemic inflammation, cardiovascular disease, metabolic syndrome, diabetes, and non-alcoholic fatty liver.
Lean Body Mass can Protect against Diabetes and Insulin Resistance:
Muscle is required to clear glucose from the blood and help to maintain healthy blood sugar levels. Insulin resistance is the first step in the progression of diabetes. It occurs when insulin secreted by the pancreas in response to a high sugar meal loses its ability to stimulate muscle to take up glucose from the blood. This results in high blood sugars which can lead to diabetes. In a large scale study of over 13,000 people over a 6-year span conducted by the UCLA School of Medicine, researchers found that higher muscle mass was associated with better insulin sensitivity and a lower risk of developing diabetes. Not only that, they found that for every 10% increase in skeletal muscle mass, there was an 11% decrease in insulin resistance. (2)
Lean Body Mass helps Recovery from Illness or Disease:
Illness and disease increase the body’s need for protein in order to heal. Often times the protein needs are far beyond what we can get from our daily diet, thus the breakdown of muscle occurs to meet the increased protein requirement. Individuals with lower levels of muscle mass will have greater difficulty meeting the demands caused by illness. In fact, loss of muscle mass is known to impact the rate of recurrence and survival from cancer. In patients with lung cancer, those who had a decrease in lean body mass due to the cancer and cancer therapy, had a higher rate of recurrence and a worse survival rate than those patients that were able to maintain muscle mass. (3)
Lean Body Mass keeps your Bones Strong and Healthy:
It has been shown that greater muscle mass is a consistent predictor of better bone health in older men and women. (4) Not only does muscle contraction create a force on the bone stimulating healthy bone remodeling, several studies have shown a positive correlation between muscle size and bone density and strength. (5) In the Mediterranean Intensive Oxidant Study, researchers found that lower amounts of skeletal muscle mass was correlated with weaker and thinner bones in elderly men. (6) Keeping your bones strong and healthy as you age requires the maintenance of adequate muscle mass and function.
Lean Body Mass Reduces your Risk of Falls and Fractures:
Reduced lean tissue, especially in the lower-leg muscles, is associated with poor balance and increased risk of falls and fractures. (5) A 2015 report from the American Society for Bone and Mineral Research found that people with decreased muscle mass had 2.3 times the risk of falling and breaking a bone, such as a hip, collarbone, leg, arm, or wrist. (7) Hip fracture is the most serious consequence of falling because it is not only associated with a high risk of death during the first year post- fracture, but also increases the risk of mortality for up to 10 years.
Do you know your Lean Body Mass?
The only way to truly know your lean body mass is to have your body composition measured. Body composition analysis breaks down your weight into muscle, fat, and body water. In my practice I use a Bioelectrical Impedance Analysis (BIA) machine to determine body composition. The BIA uses a scale to send an undetectable low voltage electric current throughout the body. Since fat is a poor conductor of electricity and muscle a good conductor, by measuring the resistance to the current the machine estimates the percent body fat and lean tissue mass. This test provides a quick and easy assessment of body composition and a great way to monitor the results of your hard work and dedication to building strong bones and a healthy body.
We all know that too much body fat is a serious health risk. But too little lean mass puts us at risk as well. Building lean body mass has health benefits beyond just becoming stronger and trimmer; it will also help you age vibrantly and with overall good health.
- Beers MH, Jones TV, Berkwits M, et al, eds. The Merck Manual of Geriatrics. Whitehouse Station, NJ: Merck Research Laboratories; 2009-2010: Section 3, chapter 31; Section 7, chapter 48; Section 8, chapter 66.
- Hornberger, T. (2014). Faculty of 1000 evaluation for Relative muscle mass is inversely associated with insulin resistance and prediabetes. Findings from the third National Health and Nutrition Examination Survey. F1000 – Post-publication peer review of the biomedical literature. doi:10.3410/f.718307005.793492146
- Kadar, L., Albertsson, M., Areberg, J., Landberg, T., & Mattsson, S. (2006). The Prognostic Value of Body Protein in Patients with Lung Cancer. Annals of the New York Academy of Sciences, 904(1), 584-591. doi:10.1111/j.1749-6632.2000.tb06520.x
- Scott, D. (2016). Influence of Sarcopenic and Dynapenic Obesity on Musculoskeletal Health and Function in Older Adults. Nutritional Influences on Bone Health, 35-48. doi:10.1007/978-3-319-32417-3_4
- Edwards, M. H., Gregson, C. L., & Patel, H. P. et al.(2013). Muscle size, strength, and physical performance and their associations with bone structure in the Hertfordshire Cohort Study. Journal of Bone and Mineral Research, 28(11), 2295-2304. doi:10.1002/jbmr.
- Szulc, P., Beck, T. J., Marchand, F., & Delmas, P. D. (2004). Low Skeletal Muscle Mass Is Associated With Poor Structural Parameters of Bone and Impaired Balance in Elderly Men-The MINOS Study. Journal of Bone and Mineral Research,20(5), 721-729. doi:10.1359/jbmr.041230
- Publishing, H. H. (n.d.). Protein at every meal may help preserve muscle strength as you age. Retrieved February 04, 2018, from https://www.health.harvard.edu/staying-healthy/protein-at-every-meal-may-help-preserve-muscle-strength-as-you-age