Malnutrition and Sarcopenia: The Importance of Muscle Mass and Strength
Guest Author: dr. Odette Bruls, (science) journalist, Lecturer at Tilburg University
Malnutrition and Sarcopenia: The Importance of Muscle Mass and Strength
Malnutrition and sarcopenia often go unnoticed in patients or other vulnerable individuals, even though they pose significant risks. Despite growing awareness, patients are not always diagnosed in time. Recognising the signs of malnutrition and sarcopenia—such as reduced appetite and difficulty with physical exertion—is crucial. Equally important is the ability to measure relevant clinical indicators, such as muscle mass and strength, easily and accurately.
Malnutrition and Sarcopenia: Complex Conditions with Various Causes
The European Society for Clinical Nutrition and Metabolism (ESPEN) defines malnutrition as an acute or chronic condition in which a deficiency or imbalance of energy, proteins, and other nutrients leads to negative effects on body composition, function, and clinical outcomes (Cederholm et al., 2016). Malnutrition, like sarcopenia, falls under the umbrella of "nutrition disorders and nutrition-related conditions."
Malnutrition is also a risk factor for sarcopenia. According to the European Working Group on Sarcopenia in Older People (EWGSOP2), sarcopenia is a progressive loss of muscle mass due to aging, leading to reduced functional capacity of the muscles (Cruz-Jentoft et al., 2018). EWGSOP2 classifies sarcopenia as an age-related condition (primary sarcopenia). However, sarcopenia can also occur secondary to pathogenic mechanisms related to illness, inactivity, or nutrition (e.g., protein deficiency). In cases of disease-related muscle loss, the term cachexia is often used.
Diagnosis of Malnutrition and Sarcopenia
For the diagnosis of both malnutrition and sarcopenia, a three-step approach has been developed by the Global Leadership Initiative on Malnutrition (GLIM) and EWGSOP2, respectively. These three steps are as follows:
| GLIM Criteria for Malnutrition | EWGSOP2 Criteria for Sarcopenia | |
| Step 1 | Validated screening tool (e.g., SNAQ, MUST, PG-SGA in the Netherlands) | Validated screening tool: SARC-F questionnaire |
| Step 2 | Presence of at least one criterion: weight loss, low BMI, low muscle mass + one criterion: reduced food intake or presence of disease / inflammation | Low muscle mass and muscle strength |
| Step 3 | Determine severity based on phenotypic (external) characteristics | Determine severity based on physical limitations |
(Beaudart et al., 2019)
As shown in the overview above, nutritional intake and low muscle mass are key criteria for diagnosing malnutrition. Meanwhile, to establish sarcopenia, muscle mass and muscle strength are the determining factors. Both can be effectively measured using instruments such as bioelectrical impedance analysis (BIA) for muscle mass and handgrip strength for muscle strength.
Certain groups of people are at a higher risk of malnutrition or sarcopenia. As previously mentioned, disease and aging are the two main contributing factors.
Disease as a Risk Factor
Diseases can increase the risk of malnutrition, and consequently, sarcopenia (cachexia). This applies to both acute and chronic conditions, such as cancer, lung diseases, heart and kidney failure, diabetes, or intestinal disorders. These diseases can disrupt metabolism and impair nutrient absorption.
However, individuals affected by these conditions often struggle to eat enough. This may be due to reduced appetite, chewing or swallowing difficulties, or even a lack of energy to shop for and prepare meals. On top of that, physical activity often becomes a challenge during illness and treatment (Roberts et al., 2021).
Ageing as a Risk Factor
Another key risk group for malnutrition and sarcopenia is the elderly. The aging process itself promotes muscle breakdown if no behavioral changes are made. From the age of 30, muscle loss begins to outweigh muscle growth, and without adequate response, individuals may develop sarcopenia later in life (De Groot, 2023). An appropriate response consists of proper nutrition combined with (strength) exercise.
Not all elderly individuals manage to maintain a balanced diet and sufficient physical activity. Even in the absence of disease, they may experience chewing and swallowing difficulties or simply reduced appetite. Additionally, social factors such as loneliness, memory loss, or low income can contribute to poor nutrition and reduced physical activity (Roberts et al., 2021).
The Vicious Cycle of Muscle Breakdown: The Impact of Inactivity on Nutrition and Health
When people, for any reason, become less physically active, muscle loss accelerates significantly. This can lead to a vicious cycle: a weakened body makes it harder to eat properly, and poor nutrition further worsens energy and protein balance, leading to even less physical activity.
Physical inactivity can have a major impact in a short time. For example, one week of bed rest can already result in a loss of 1.4 kg of muscle tissue. Considering an average muscle mass of 35 kg for a healthy 30-year-old and 25 kg for a healthy 80-year-old, this loss quickly becomes substantial (De Groot, 2023).
Strengthening Muscle Tissue with Strength Training and Protein
Although muscle loss due to inactivity can be reversed through training, studies show that frail older adults require three to six months of strength training to regain muscle mass, ideally combined with a protein-rich diet (De Groot, 2023).
Protein plays a crucial role in treating sarcopenia. Studies in both healthy adults (Morton et al., 2018) and older adults confirm this. The Dutch ProMuscle study demonstrated that when frail older adults consumed at least 25g of protein per meal in combination with strength training, their muscle mass and strength significantly increased (Tieland et al., 2012).
Valuable Data for Prevention and Treatment
Preventing and treating malnutrition and sarcopenia starts with proper screening. Measuring muscle mass and strength should be a standard component of this process. Increasingly, dietitians and healthcare professionals are using measurement tools to assess muscle mass and strength.
While MRI, CT, and DEXA scans provide highly accurate muscle mass assessments, they are time-consuming, expensive, and not accessible to everyone. Bioelectrical impedance analysis (BIA) is a suitable alternative for dietitians, offering precise estimations and the flexibility to be used in any setting, including patients' homes.
Additionally, measuring upper arm circumference can provide an initial indication of muscle mass, and a simple handgrip strength test can assess muscle strength.
Measuring is knowing. Various accessible tools provide valuable data on muscle mass and strength, enabling healthcare professionals to tailor treatments to individual patients and effectively monitor treatment outcomes.
References
Beaudart, C., Sanchez-Rodriguez, D., Locquet, M., Reginster, J.-Y., Lengelé, L., & Bruyère, O. (2019). Malnutrition as a Strong Predictor of the Onset of Sarcopenia. Nutrients, 11(12), 2883. https://doi.org/10.3390/nu11122883
Cederholm, T., Barazzoni, R., Austin, P., Ballmer, P., Biolo, G., Bischoff, S., Compher, C., Correia, I., Higashiguchi, T., Holst, M., Jensen, G., Malone, A., Muscaritoli, M., Nyulasi, I., Pirlich, M., Rothenberg, E., Schindler, K., Schneider, S., De van Der Schueren, M., . . . Singer, P. (2016). ESPEN guidelines on definitions and terminology of clinical nutrition. Clinical Nutrition, 36(1), 49–64. https://doi.org/10.1016/j.clnu.2016.09.004
Cruz-Jentoft, A. J., Bahat, G., Bauer, J., Boirie, Y., Bruyère, O., Cederholm, T., Cooper, C., Landi, F., Rolland, Y., Sayer, A. A., Schneider, S. M., Sieber, C. C., Topinkova, E., Vandewoude, M., Visser, M., Zamboni, M., & Writing Group for the European Working Group on Sarcopenia in Older People 2 (EWGSOP2), and the Extended Group for EWGSOP2 (2019). Sarcopenia: revised European consensus on definition and diagnosis. Age and ageing, 48(1), 16–31. https://doi.org/10.1093/ageing/afy169
De Groot, L. (2023). Sacropenie. In Soeters et al. (Red.) Leerboek voeding (pp.307-318). Bohn Stafleu van Loghum. https://doi.org/10.1007/978-90-368-2868-0
Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., Aragon, A. A., Devries, M. C., Banfield, L., Krieger, J. W., & Phillips, S. M. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British journal of sports medicine, 52(6), 376–384. https://doi.org/10.1136/bjsports-2017-097608
Roberts, S., Collins, P., & Rattray, M. (2021). Identifying and Managing Malnutrition, Frailty and Sarcopenia in the Community: A Narrative Review. Nutrients, 13(7), 2316. https://doi.org/10.3390/nu13072316
Tieland, M., Dirks, M. L., van der Zwaluw, N., Verdijk, L. B., van de Rest, O., de Groot, L. C., & van Loon, L. J. (2012). Protein supplementation increases muscle mass gain during prolonged resistance-type exercise training in frail elderly people: a randomized, double-blind, placebo-controlled trial. Journal of the American Medical Directors Association, 13(8), 713–719. https://doi.org/10.1016/j.jamda.2012.05.020