Rethinking obesity treatments: The importance of body composition

Weight loss medications should only be prescribed following a thorough evaluation of both the potential health benefits and the associated risks or side effects. Careful consideration of these factors is essential to ensure that the therapeutic benefits outweigh any adverse effects. Additionally, treatment outcomes should be tailored to the individual's specific clinical condition, taking into account their unique medical history, current health status, and long-term wellness goals. This personalised approach ensures that the intervention is both safe and effective, promoting overall health improvement.

But why? Isn't it the most straightforward approach to address obesity without complication?

While the common advice to "eat less and move more" is still promoted by some healthcare providers for individuals living with obesity, I aim to foster greater empathy and understanding within both the broader healthcare community and my own clinical practice.

The risks of solely focusing on weight loss

Focusing only on weight loss, without considering lifestyle modifications or body composition changes, can be risky. This approach may lead to lasting negative effects on an individual's health. Ignoring critical factors like preserving muscle mass, improving metabolic health, and adopting sustainable habits can hinder long-term well-being.

Neglecting these aspects could result in metabolic imbalances, loss of muscle strength, and an increased likelihood of regaining weight. Therefore, a holistic approach that emphasises dietary changes, lifestyle adjustments, and attention to body composition is essential for promoting optimal health and preventing long-term complications.

Understanding the complexity of obesity

The reality is that many still struggle to grasp the complex biological basis of obesity as a medical condition. This misunderstanding parallels the struggle to recognise depression as a neurochemical and biological disease. Similarly, obesity is a multifaceted condition influenced by genetics, physiology, and various biological mechanisms, making it more challenging to comprehend.

During a recent lecture, I asked everyone in the room if they had ever seen an obese individual and silently thought, "Maybe they should exercise more or eat less?" To my surprise, every hand went up. Now, consider this: when you encounter someone with cancer, do you think, "Perhaps they should quit smoking or adopt a healthier diet?" The answer is clearly no. But what if I told you that 40% of cancer cases could be avoided with dietary and lifestyle changes?

This illustrates why I began my lecture this way. Addressing obesity necessitates confronting the associated stigma. It’s impossible to educate individuals about managing obesity without exploring its root causes, especially in a room full of healthcare professionals.

Once we achieve a deeper understanding of obesity as a medical condition, we can move beyond biases and misconceptions, dismantling stigmatising attitudes. This knowledge helps reduce discrimination and encourages a compassionate, scientifically informed approach to treatment.

The role of skeletal muscle mass in weight loss and health

The significance of skeletal muscle mass is increasingly recognised in the medical community. One reason for this growing attention is the impact of GLP-1 receptor agonists, effective weight-loss medications that can lead to substantial muscle loss. Studies show that muscle loss is reflected in a reduction in fat-free mass (FFM). This muscle loss is mainly attributed to the extent of weight loss rather than a direct effect of the GLP-1 receptor agonists, although more research is needed.

In contrast, non-pharmacological caloric restriction typically leads to smaller amounts of weight loss and FFM reductions of 10% to 30%. The rate of muscle mass decline associated with GLP-1 receptor agonists exceeds the expected natural age-related loss of approximately 0.8% per year (or 8% per decade) between ages 40 and 70.

Impact of muscle loss on physical function and muscle quality

It's hypothesised that significant reductions in FFM from short-term weight loss may not impair physical function, such as muscle strength. While muscle mass and strength generally correlate positively, they don’t always decrease together, especially in cases of obesity, metabolic disorders, or ageing. Improvements in muscle composition, like a reduction in myosteatosis (fat infiltration into muscle), could enhance muscle quality, defined as the ratio of muscle strength to muscle mass. If muscle composition improves, overall body composition could also improve, maintaining or even enhancing muscle function and strength. 

Broader implications of muscle loss beyond strength

Although evidence on the effects of GLP-1 receptor agonists is limited, findings from bariatric and metabolic surgery suggest that muscle loss doesn’t necessarily lead to a loss of strength. However, muscle strength is just one aspect of muscle's significance. Beyond its functional role, skeletal muscle plays crucial metabolic functions beyond movement and physical strength. It acts as a reservoir for amino acids during stress, trauma, or infection and synthesises and stores glutamine, vital for nitrogen transport and immune function.

Moreover, muscle mass is critical for glucose homeostasis, aiding in glucose uptake in response to insulin and helping maintain normal blood sugar levels. Muscle-derived myokines - signalling molecules released by muscle cells - act as endocrine factors influencing metabolism, energy balance, and inflammation. These myokines also regulate immune system function. Therefore, preserving skeletal muscle mass is essential for maintaining physical function and supporting metabolic health, immune response, and overall well-being.

Recent advancements in myokine research have deepened our understanding of muscle-organ communication and highlighted myokines as potential therapeutic targets and biomarkers. This is especially important for exercise-based treatments of chronic diseases such as cancer, diabetes, and neurodegenerative disorders.

In summary, the roles of skeletal muscle extend far beyond movement, highlighting the importance of preserving muscle mass during weight loss interventions. Both clinicians and patients must understand the broader implications of muscle health to ensure that treatment strategies are optimized for long-term wellness.

The importance of measuring body composition

Accurate measurement of body composition is crucial for understanding individual health, particularly concerning obesity and weight management. Unlike traditional metrics like BMI, which only consider total body weight, body composition analysis - such as Bioelectrical Impedance Analysis (BIA) and Bioimpedance Spectroscopy (BIS) - provides a nuanced understanding of fat, muscle, and other tissue proportions. This detailed insight is essential for assessing overall health and developing personalised treatment strategies.

For instance, focusing on fat loss while preserving muscle mass can improve metabolic health and reduce the risk of chronic diseases. Additionally, tracking body composition helps evaluate the effectiveness of weight loss interventions, ensuring they don’t inadvertently lead to muscle loss - an especially important consideration with weight loss medications like GLP-1 receptor agonists.

Advice for individuals seeking support

As a dietitian, I encourage individuals seeking to manage their weight and improve their health to consider the following:

1. Focus on body composition, not just weight - Understand that achieving a healthy body composition is more beneficial than merely focusing on the number on the scale. Aim to reduce body fat while preserving or increasing muscle mass.
2. Adopt a balanced diet: Incorporate a variety of whole foods, including fruits, vegetables, lean proteins, and whole grains. These foods provide essential nutrients that support metabolic health and overall well-being.
3. Prioritise strength training: Engage in regular strength training exercises to build and preserve muscle mass. This can enhance your metabolism and improve physical function.
4. Stay hydrated: Adequate hydration is essential for overall health, including maintaining muscle function and supporting metabolic processes.
5. Consult a healthcare professional: If considering weight loss medications, discuss with a healthcare provider or dietitian to determine the most suitable approach based on your unique health profile.
6. Be patient and compassionate with yourself: Recognise that sustainable weight loss and health improvement take time. Focus on making gradual, long-term changes rather than seeking quick fixes.

By following these guidelines, you can develop a healthier relationship with food and your body, leading to better health outcomes and improved quality of life.

References

• Heymsfield, S.B., 2024. Advances in body composition: a 100-year journey. International Journal of Obesity, [online] Published online April 20. Available at: https://doi.org/10.1038/s41366-024-01511.
• Chen, L., Nelson, D.R., Zhao, Y. and et al., 2013. Relationship between muscle mass and muscle strength, and the impact of comorbidities: a population-based, cross-sectional study of older adults in the United States. BMC Geriatrics, 13, p.74.
• Severinsen, M.C.K. and Pedersen, B.K., 2020. Muscle-organ crosstalk: the emerging roles of myokines. Endocrine Reviews, 41(4), p.bnaa016. DOI: 10.1210/endrev/bnaa016.
• The Lancet Diabetes & Endocrinology, 2024.Muscle matters: the effects of medically induced weight loss on skeletal muscle. The Lancet Diabetes & Endocrinology, [online] Available at: https://www.thelancet.com/journals/landia/article/PIIS2213-8587(24)00272-9/abstract (Accessed 24th September 2024).