Gildardo Uribe Gil
ND- MgSC, Phd (c) en SP
Obesity is a complex condition that affects millions of people worldwide, with WHO projections indicating that approximately 4 billion adults will be living with overweight or obesity by 2030. In addition to metabolic and cardiovascular impacts, excess body fat is associated with multiple comorbidities that affect quality of life. In the search for effective therapeutic solutions, glucagon-like peptide-1 receptor (GLP-1R) agonists have proven to be a promising option for the treatment of obesity, with positive effects on weight control and metabolic regulation (Wang et al., 2023).
Although the use of these drugs has shown benefits in reducing fat tissue, recent research has indicated that they may also affect muscle mass, which carries important clinical implications. The reduction of muscle mass can compromise basal metabolism, physical functionality, and the regulation of energy homeostasis, especially in vulnerable populations such as older adults or individuals with underlying metabolic conditions (Celis-Morales et al., 2024). Due to this impact on body composition, monitoring patient progress through bioelectrical impedance analysis (BIA) has become a fundamental tool for assessing the quality of weight loss and optimizing therapeutic intervention processes (Roca-Rodríguez et al., 2017).
GLP-1 agonists, such as liraglutide and semaglutide, act on the central nervous system by regulating appetite and prolonging the sensation of satiety, contributing to reduced caloric intake. Additionally, these drugs modulate insulin secretion and decrease glucagon production, which supports glucose homeostasis and a better energy balance (Drucker, 2018). Recent studies have shown that patients treated with GLP-1 agonists may experience significant reductions in fat mass, accompanied by improvements in insulin sensitivity and other metabolic parameters. However, it has also been reported that weight loss includes a concurrent decrease in muscle mass, which presents challenges for maintaining long-term health (Evans & Cummings, 2024).
The muscle loss associated with GLP-1 agonist use can be attributed to multiple factors. Firstly, the drastic reduction in caloric intake can lead to a prolonged energy deficit, limiting the availability of essential proteins for muscle synthesis. Furthermore, it has been suggested that these drugs may influence the secretion of anabolic hormones, affecting the preservation of lean tissue. Reduced physical activity due to decreased appetite and changes in energy perception may also contribute to this process. Additionally, some studies have reported changes in fluid distribution, with alterations in the balance between intracellular and extracellular water, which could affect the structural quality of muscle tissue (Hong, 2019; Uchiyama, 2023).
From a clinical perspective, the reduction of muscle mass induced by these drugs may lead to significant consequences. A decreased basal metabolism can impair the body’s ability to maintain energy homeostasis, while reduced physical functionality increases the risk of frailty and decreased mobility. There is also an elevated risk of developing sarcopenic obesity, particularly in older patients and those with preexisting metabolic disorders. Therefore, it is essential that GLP-1 treatments be complemented by appropriate nutritional strategies and a structured exercise program to preserve muscle mass and ensure a healthy body composition (Wilding, 2021).
Since the weight loss induced by these agonists affects both fat and muscle tissue, bioelectrical impedance analysis (BIA) emerges as a key tool for patient monitoring. This technology enables precise assessment of body composition, providing specific data on the distribution of lean mass, fat tissue, and hydration. In addition, BIA provides information on electrical biomarkers such as Phase Angle (PA), a fundamental indicator of cellular quality and the patient’s metabolic state (Whyte et al., 2019).
The use of devices such as Aminogram allows for detailed tracking of GLP-1 effects on body composition, helping determine whether weight loss is occurring in a healthy way. Fat mass measurement is key for evaluating treatment effectiveness, while analysis of appendicular muscle mass and the ASMI index helps identify changes in physical functionality and the risk of sarcopenia. Active cellular mass is an essential parameter for monitoring changes in basal metabolism, intracellular fluid regulation, and potassium loss, which impacts muscle function. Similarly, the balance between extracellular and intracellular water can reflect alterations in cellular hydration, providing crucial data for therapeutic adjustments. Phase angle has proven to be a valuable biomarker for assessing health and nutritional status, while the impedance ratio (Z200/Z5) is useful for analyzing cellular integrity, inflammation, and fluid regulation. These parameters enable the development of intervention strategies based on objective data, ensuring that weight loss with GLP-1 is effective and does not compromise muscle quality (González-Ortiz et al., 2011).
Conclusions
GLP-1 agonists have shifted the paradigm in obesity treatment by providing an effective pharmacological alternative for weight reduction. However, their use requires careful evaluation to ensure the preservation of muscle mass and the patient’s metabolic functionality.
Monitoring with advanced tools such as bioimpedance, combined with nutritional strategies and appropriate physical activity, allows for the optimization of therapeutic intervention and ensures sustainable long-term outcomes in obesity management.
References
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