Why muscle mass matters in keeping weight off long term

When we think about maintaining weight loss for good, it's easy to focus on the number on the scales. But there's another important piece of the puzzle: your body composition, or the balance of muscle, fat and bone in your body.

Muscle plays a key role in supporting long-term weight maintenance, which means maintaining your weight isn't just about reducing body fat. Preserving and building muscle can be just as important for supporting your health, strength and long-term results.

Let's take a closer look at what muscle mass is, why it matters, and how you can maintain it throughout your weight maintenance journey.

Key takeaways

• Muscle mass is an important part of weight maintenance, helping to support your strength, mobility aFnd overall health.
• Some muscle loss can happen during weight loss, but getting enough protein and including strength-based exercise can help protect it.
• Focus on building healthy habits, not hitting a perfect number. Maintaining or improving your muscle mass relative to your own goals is what matters most.

What is muscle mass?

Muscle mass is a fancy term for the amount of smooth muscle tissue in your body. It includes your skeletal, smooth, and cardiac muscles. Your muscle mass makes up only one part of your overall body composition, because your body is also made up of fat, bone and water.

What is skeletal muscle mass?

When people talk about muscle mass, they're usually referring to skeletal muscle mass. These are the muscles attached to your bones that help you move, maintain your balance, and carry out everyday activities, from walking up the stairs to lifting shopping bags.

Skeletal muscle does much more than support strength and mobility. It also plays an important role in long-term weight maintenance, which is why preserving muscle during and after weight loss is so important.

"Skeletal muscle is the type of muscle that helps you move, stay active and maintain your strength. It's easy to focus solely on weight loss, but protecting your muscle mass is just as important. Maintaining muscle can support your overall health, help you stay physically active, and make it easier to maintain your weight in the long term."

Ayesha Bashir, Weight Loss Expert and Prescribing Pharmacist

Muscle mass percentage explained

Muscle mass percentage is the portion of your total body weight made up of skeletal muscle.

Even though body weight is typically used in healthcare assessments, there is scientific evidence to suggest that body composition measurements are a better indicator of your overall health than body weight alone. This is because they account for differences in the proportion of fat and fat-free mass that vary naturally between different people.

For example, these proportions can vary by sex and age, and are determined by multiple factors, including your genetics and activity levels. In short, body composition accounts for the fact that two people of the same height and body weight can look completely different due to having different body compositions.

Why muscle mass matters for weight maintenance

Your muscles support all your bodily functions, helping to control your heartbeat, breathing and digestion, among other things. However, your muscle tissue is also metabolically active, meaning it burns calories, even when you’re not moving. This is why people with more muscle mass tend to have higher resting metabolic rates. As a result, your muscles also play an essential role in helping you maintain your weight.

Can weight loss lead to muscle loss?

Yes, when you lose weight, alongside fat, you can also lose some muscle mass, particularly if you’re losing weight quickly, not eating enough protein, or not doing any strength-based exercise.

This is why preserving muscle should be a priority throughout both weight loss and maintenance. Muscle plays an important role in supporting strength, mobility and overall health, and it can also make it easier to maintain your weight in the long term because muscle tissue requires more energy than fat tissue. Put simply, the more muscle mass you maintain, the more calories your body burns throughout the day to maintain it, even when you're at rest.

If you're using weight loss medication, paying attention to your protein intake as part of a balanced nutrition becomes especially important. Medications such as Wegovy, Mounjaro and Foundayo can reduce your appetite, which means you may naturally eat less. While this can support weight loss, it can also make it harder to get the nutrients your body needs to protect muscle mass if you're not eating a balanced diet.

Signs you may be losing muscle mass

If you've lost weight, it isn't always easy to tell whether you've lost muscle mass as well. While some people notice that their muscles appear less defined, there are other signs of losing muscle mass, including:

• Feeling weaker than usual
• Finding everyday activities, such as carrying shopping or gardening, more challenging
• Struggling with exercises that previously felt manageable
• Feeling less stable, balanced or mobile

It's important to remember that these signs don't always mean you're losing muscle mass. They can sometimes be linked to other health conditions or changes in your overall health. If you're concerned about a loss of strength, mobility or muscle mass, speak to a healthcare professional for personalised advice.

What is a good muscle mass percentage?

There isn't one "ideal" muscle mass percentage that everyone should aim for. What's considered healthy can vary depending on factors such as your age, sex, body size, genetics, and activity levels.

For example, someone who regularly does strength training is likely to have a higher muscle mass percentage than someone who is less active, and that's perfectly normal. Muscle mass also tends to change naturally throughout life, with many people gradually losing muscle as they get older.

Rather than focusing on reaching a specific number, it's often more helpful to think about whether you're maintaining or improving your muscle mass relative to your own circumstances and goals. Building or preserving muscle can support your strength, mobility, metabolism, and overall health, regardless of the exact percentage.

Average muscle mass for women and men

Men and women naturally tend to have different amounts of muscle mass, but there's no single figure that's considered "normal" for everyone. Your muscle mass is influenced by a range of factors, including your age, genetics, body size, activity levels, and overall health.

On average, muscle makes up around 40% of total body weight, although this can vary significantly from person to person. Rather than comparing your muscle mass to someone else's, focus on what you can do to support your own muscle health.

How can you check your muscle mass?

Most widely available muscle mass calculators are a rough estimation. For a more accurate picture, there are various types of imaging tests that can measure your muscle mass. However, they are typically expensive and can produce different results, even in the same individual. Options include:

• magnetic resonance imaging (MRI)
• dual-energy X-ray absorptiometry (DEXA)
• bioimpedance analysis
• D₃-creatine dilution
• computed tomography (CT)
• ultrasound

It’s perhaps more important to measure your muscle strength, as this will help you stay active and able to perform your daily activities. A healthcare professional can help you do this using a hand dynamometer, which measures handgrip strength, which is a good indicator of overall muscle strength.

How to increase muscle mass during maintenance

Here are some of our top tips for maintaining and even increasing your muscle mass while maintaining your weight:

• Prioritise protein: Eating plenty of protein can help to maintain your muscle mass, even when you’re eating less overall. Good sources of protein include meat, eggs, fish, beans and peas, nuts and seeds.
• Include strength training: Resistance training can help you preserve your current muscle mass and improve your muscle strength. It works by making your muscles work against a weight or force. Thankfully, you don’t need to go to a gym to do resistance exercises. Examples you can do at home include wall press-ups, biceps curls with a weight, resistance band exercises.
• Stay active overall: While resistance training is specifically good for maintaining and building muscle mass, staying active in other ways can help to maintain your overall health. For example, flexibility exercises, like yoga, tai chi and Pilates, can help your joints maintain the movement they need to support your everyday tasks.

Building strength is part of maintaining weight loss long term

Maintaining weight loss means building habits that help you feel strong, healthy and confident in your body for the long term. Small, sustainable steps, such as prioritising protein and including regular strength-building activities, can help you protect your muscle mass and support your ongoing success.

Muscle maintenance, however, is just one piece of the puzzle. For a complete look at the habits, mindset and strategies that support long-term success, we have just the guide for you.

FAQs

Can you build muscle while maintaining your weight?

Yes. It's possible to build muscle while maintaining your weight, particularly if you're new to strength training or have recently increased your protein intake. In some cases, you may gain muscle while losing body fat, resulting in little change on the scales even though your body composition is improving.

Does more muscle help you maintain weight loss?

Muscle tissue requires more energy than fat tissue, meaning it can help increase the number of calories your body burns throughout the day. Maintaining muscle mass can also support an active lifestyle, making it easier to sustain healthy habits and maintain your weight long term.

Can you lose muscle on Wegovy, Mounjaro or Foundayo?

Weight loss from any cause, including weight loss medication, can lead to some muscle loss alongside fat loss. This is why it's important to eat enough protein and include regular strength-building exercise while taking medication. These habits can help protect your muscle mass as you lose weight.

How can I prevent muscle loss during weight loss?

The best ways to support muscle maintenance are to eat enough protein, stay physically active, and include resistance training in your routine. Activities such as weightlifting, bodyweight exercises, resistance bands and Pilates can all help preserve muscle while you're losing weight.

What is the best exercise for maintaining muscle mass?

Any form of resistance training can help maintain and build muscle. This includes lifting weights, using resistance bands, bodyweight exercises such as squats and press-ups, or activities like Pilates. The most effective exercise is the one you can do consistently as part of your lifestyle.

Can you maintain muscle mass without going to the gym?

Absolutely. While gyms can be helpful, they're not essential. Home workouts, resistance bands, bodyweight exercises, gardening, carrying shopping and other everyday activities can all contribute to maintaining strength and muscle mass. The key is staying active and challenging your muscles regularly.

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