What you need to know about sarcopenic obesity and cancer

Most of us are familiar with the risks of obesity and the challenges of age-related muscle loss (known as sarcopenia). But what happens when these two conditions occur together? Welcome to the growing health concern called sarcopenic obesity, and it's especially dangerous for people living with cancer.

What is sarcopenic obesity?

Sarcopenic obesity is a condition where too much body fat and too little muscle mass coexist. This isn’t just about looking overweight or under-toned - it’s a metabolic and inflammatory state that poses real risks to health. Originally thought to affect mainly older adults, researchers are now discovering that sarcopenic obesity is becoming more common across age groups, particularly in those with chronic diseases like cancer.

Why does this matter for cancer patients?

For cancer patients, body composition matters more than ever. People with sarcopenic obesity tend to have poorer treatment outcomes, such as:

• more severe side effects from chemotherapy
• longer hospital stays
• increased physical disability
• lower survival rates

This is because both obesity and muscle loss contribute to inflammation, insulin resistance, and oxidative stress, all of which can make cancer worse and harder to treat.

What’s going on inside the body?

Sarcopenic obesity creates a dangerous imbalance in metabolism. Here’s what’s happening:

• Fat builds up inside the muscle (a condition called myosteatosis), making muscles weaker.
• Muscles lose their ability to use sugar and fat properly, leading to insulin resistance.
• Inflammation increases, driven by the fat tissue and muscle breakdown.
• The body starts breaking down muscle even faster, often feeding cancer cells in the process.

It’s a vicious cycle that weakens the body just when it needs to be strongest.

Why is it so hard to detect?

One big challenge is diagnosis. People with sarcopenic obesity may appear to be a "normal" weight or even overweight, but hidden under the surface is poor muscle quality. Traditional methods like BMI (body mass index) miss the bigger picture.

Special scans like DEXA, CT, or bioelectrical impedance analysis (BIA) can measure muscle and fat more accurately, but these tools aren’t always available - especially in routine cancer care.

Can anything be done?

Yes. The good news is that sarcopenic obesity can be treated and even prevented - but it takes a multi-pronged approach:

• Nutrition: Eating enough high-quality protein, healthy fats (especially omega-3s), and essential nutrients is critical to support muscle maintenance.
• Exercise: Resistance training (like lifting weights or using resistance bands) and aerobic exercise help build and preserve muscle.
• Innovative therapies: Techniques like muscle electrostimulation and whole-body vibration therapy show promise for people who struggle with conventional exercise.

What you can do to protect your muscles and support recovery

Here are practical, evidence-based tips that can help:

1. Prioritise protein at every meal

Muscle maintenance depends on adequate protein intake. During cancer treatment, aim for 1.2-1.5g of protein per kg of body weight per day, unless your healthcare team advises otherwise.

Good sources include:

• eggs, fish, poultry, lean red meat
• dairy products (milk, yoghurt, cheese)
• plant-based options like beans, lentils, tofu, and soya mince
• nutritional supplements if eating is difficult

Tip: Spread protein across the day - include a protein-rich food at every meal and snack.

2. Don’t cut calories unnecessarily

Weight-loss during cancer is often unintentional and includes muscle loss, not just fat. Even if someone is overweight, a 'weight-loss' diet is not appropriate during active treatment unless supervised by a dietitian.

Instead:

• Eat small, frequent meals.
• Add energy to meals using healthy fats like olive oil, nut butter, and avocado.
• Use oral nutrition supplements (like Fortisip, Aymes or prescribed shakes) if food intake is low.

3. Focus on nutrient-dense foods

Micronutrients like vitamin D, magnesium, and B vitamins are all vital for muscle health. Try to include:

• leafy greens (spinach, kale)
• wholegrains (oats, brown rice, wholemeal bread)
• oily fish (salmon, mackerel) for omega-3s
• nuts and seeds

Note: Vitamin D is often low in people with cancer. Speak to your GP or dietitian about testing and supplementation (typical UK guidance: 10 micrograms/day).

4. Stay hydrated and monitor appetite

Dehydration can worsen fatigue and appetite. Sip fluids throughout the day and don’t ignore early signs of poor appetite or taste changes these are common during treatment and can lead to further nutritional decline.

Speak to your care team early if you're struggling to eat, as early dietetic support makes a big difference. It’s also essential to personalise care for each cancer patient what works for one person may not work for another.

Right now, there are no universal guidelines to diagnose or treat sarcopenic obesity, especially in cancer patients. That needs to change. The sooner we can screen, identify, and address sarcopenic obesity, the better we can support people living with cancer and potentially save lives. Sarcopenic obesity is a silent but serious health concern, particularly in cancer patients. If you or someone you love is undergoing cancer treatment, talk to your healthcare team about body composition, muscle health, and nutritional support. Understanding what’s happening beneath the surface could make all the difference.

Sarcopenic obesity is a silent risk - but it doesn’t have to be. With early dietetic input, personalised support, and better awareness in cancer care, we can help people preserve muscle, tolerate treatment better, and improve their quality of life.

References:

Axelrod, C. L., Dantas, W. S., & Kirwan, J. P. (2023). Sarcopenic obesity: Emerging mechanisms and therapeutic potential. Metabolism, 146, 155639. https://doi.org/10.1016/j.metabol.2023.155639

Jurdana, M., & Cemazar, M. (2024). Sarcopenic obesity in cancer. Radiology and Oncology, 58(1), 1–8.