Why Muscle Matters: Protein, Muscle Health and How to Protect Your Strength

The Protein Chronicles — Part 2

Part 1 of The Protein Chronicles introduced the thousands of different proteins our bodies build and rebuild on a continuous basis.

It also introduced the 20 standard amino acids that the body uses to create those proteins, including the nine essential amino acids we must obtain through our diet.

Part 2 turns its attention to muscle, a tissue vital for our health, strength and longevity.

Your muscle is your might

I am becoming more and more of a muscle-centric nutritionist, and that’s not simply because I work with a lot of athletes.

It’s because our health, strength, body composition and physical function are influenced, to a significant extent, by the quantity and quality of our muscle tissue.

Consider the following.

1. Muscle is a major site of fat oxidation

Our muscles are important users of fat as fuel, particularly during lower-intensity exercise and at rest.

If you want to reduce body fat or maintain a healthy body composition, protecting your muscle tissue should be a priority.

It really doesn’t help that some of the weight lost during calorie-restricted diets comes from muscle rather than fat. The more aggressively we restrict calories, the greater the challenge can be to preserve that valuable tissue.

I’d apply the same thinking to athletes who put in significant miles without enough carbohydrate to support their training.

It’s true that at lower exercise intensities, we can use body fat effectively as fuel. But fat oxidation alone cannot meet the energy demands of every exercise intensity. The contribution from fat depends on the individual, the duration and intensity of exercise, and their training and nutritional status.

Carbohydrate stored as glycogen in our muscles and liver is another important fuel source. These stores are limited, and prolonged exercise with inadequate fuelling can increase the body’s reliance on other energy sources, including amino acids.

Under some circumstances, those amino acids can come from muscle tissue.

This is not a strategy I’d recommend for protecting muscle or supporting recovery.

It’s akin to building a beautiful timber-frame home and then using parts of the structure for firewood.

2. Muscle is a major site of glucose disposal

Something has to happen to the energy contained in the carbohydrates we eat.

Carbohydrates are broken down into simple sugars, including glucose, which the body uses to supply energy to its cells.

Our muscles are a major destination for that glucose. They use it for energy and store some of it as glycogen for future use.

The more muscle we have, the greater our potential capacity to store glycogen, although the actual amount also depends on training status, recent exercise and diet.

What happens when those energy stores are well stocked and we continue to consume more energy than we need?

The body has several ways of managing the surplus. Over time, when energy intake consistently exceeds energy expenditure, excess energy can contribute to increased body fat.

Muscle mass is part of this picture because it influences glucose uptake, energy use and storage capacity.

When we lose muscle

When we lose muscle, we can reduce our capacity to use glucose and store glycogen. Maintaining muscle helps preserve these important functions.

Ever wondered why maintaining weight or body composition can become more difficult after repeated periods of severe calorie restriction?

Loss of muscle may be one part of the explanation, alongside changes in energy expenditure, appetite and other physiological adaptations.

Of course, the reverse is also true. Building and maintaining muscle, particularly through resistance training, helps support glucose regulation and metabolic health.

3. Muscle contains mitochondria — our cellular energy producers

Mitochondria are the little energy-producing structures within our cells. They help convert the energy in food into a form our bodies can use.

Skeletal muscle contains many mitochondria, and endurance training can stimulate the development of more mitochondria within muscle tissue.

This is one of the ways our muscles adapt to exercise and become better at using oxygen to produce energy.

And yes, nutrition matters here, too. We need adequate energy, protein and a range of other nutrients to support the adaptations we ask our bodies to make.

4. Muscle maintains strength, mobility and function

This might seem like an obvious one, but consider what it means across a lifetime.

Muscle helps us climb stairs, get out of a chair, carry shopping, maintain balance and recover from physical challenges.

And while that sounds like a short list of everyday activities, if you’re 80 years old, it can mean the difference between independence and needing help.

Muscle is not simply about aesthetics or athletic performance.

It is about living well.

How do we lose muscle?

How many of the following can you tick?

• A lack of calories or a pattern of restrictive dieting over many years.
• A lack of movement, particularly as we age.
• Inadequate protein intake.
• Hormonal changes associated with ageing and menopause.
• Prolonged endurance exercise without sufficient fuelling and recovery.
• Injury or surgery that reduces weight-bearing activity.
• Insufficient resistance exercise to maintain or build strength.

Several of these factors can overlap, making it harder to preserve muscle as we get older.

But here’s the good news: there is plenty we can do to support muscle maintenance and, in many cases, build muscle too.

Nutrition is one part of that equation. Appropriate resistance training, sufficient energy intake, sleep and recovery all matter.

Let’s start with protein.

How much protein do we need?

Although I want you to think in terms of amino acid intake, recommendations are generally expressed as grams of protein.

For most healthy adults, the recommended dietary allowance (RDA) is around 0.8g of protein per kilogram of body weight per day.

But what does that number actually tell us?

It provides a general benchmark for meeting basic protein requirements. It isn’t necessarily the amount that will best support every individual’s goals.

Do you want to build muscle? Are you an athlete or an endurance athlete? Are you recovering from surgery or an injury? Are you trying to lose body fat? Are you navigating menopause or ageing?

Your circumstances matter.

The RDA is designed to meet the needs of most healthy adults and prevent inadequacy. It isn’t a tailored prescription for optimising muscle growth, athletic performance or recovery.

For many active adults, a daily intake in the region of 1.2–1.8g per kilogram of body weight can be a useful starting point for supporting muscle maintenance and training adaptation. The appropriate amount depends on your training, energy intake, age, health and individual circumstances.

For people with a higher body weight, simply multiplying actual body weight by a protein target may not always be the most appropriate approach. A reference weight or adjusted calculation may be more suitable, depending on the individual and their goals.

This is where context matters.

There is no single number that works for everybody.

Protein needs as we age

As we age, we need to think about protein intake a little differently.

It’s not just about the total amount we consume across the day. The amount we eat at each meal matters, too.

Children need protein to grow and develop, and their requirements vary with age, growth and body size. For adults, the picture changes: maintaining muscle becomes an increasingly important consideration, particularly as we get older.

Research suggests that older muscle can be less responsive to a small serving of protein than younger muscle. This is sometimes described as anabolic resistance.

In practical terms, an older adult may benefit from consuming a larger amount of protein at a meal to stimulate muscle protein synthesis effectively.

For many adults, around 25–30g of high-quality protein per meal can be a useful starting point. Older adults and those with greater needs may benefit from approximately 30–40g or more, depending on body size, activity and the protein source.

These are guidelines, not rigid thresholds.

The important point is that we need to consider both our total daily intake and how we distribute it throughout the day.

That is key information.

Growing muscle by stimulating muscle protein synthesis

Let’s go back to leucine, one of the nine essential amino acids we introduced in Part 1.

Leucine plays a particularly important role in signalling the body’s muscle-building machinery to get to work.

I use the word signal purposefully here.

Consuming a sufficient amount of leucine, alongside the other essential amino acids, helps stimulate muscle protein synthesis (MPS) — the process through which our bodies build new muscle proteins.

For many adults, around 2–3g of leucine in a meal can provide a useful stimulus. That amount is often found in a serving of approximately 25–30g of high-quality protein, although the precise amount depends on the food or protein source.

Here’s the lightbulb moment: the protein provides both the signal and the building materials.

Leucine helps initiate the process, but it cannot build muscle on its own. The body also needs the other essential amino acids, sufficient energy and the right stimulus — including resistance exercise — to support muscle growth and repair.

Muscle protein synthesis rises after a protein-containing meal, and the response changes over the following hours. It isn’t simply an on-off switch that stays activated until leucine returns to baseline.

Rather than chasing a precise timing window, focus on providing your body with adequate protein at regular meals throughout the day.

Where do we find leucine?

Leucine is present in both animal and plant foods, although the amounts vary.

Whey protein isolate is particularly rich in leucine and provides all nine essential amino acids.

Other useful sources include milk, yoghurt, eggs, meat and fish. Plant sources include soya beans, tofu, lentils, peas, peanuts, oats and seeds, although the protein and leucine content varies considerably.

Soya and pea protein isolates can also provide useful amounts of leucine and other essential amino acids, making them practical options for people following plant-based diets.

The aim is not simply to consume leucine. It is to get enough total protein, including all the essential amino acids, to support the body’s ongoing work of building and rebuilding muscle.

Want to put this into practice?

Part 3, the final instalment of The Protein Chronicles, looks at how to put protein knowledge into practice through everyday food choices and meal timing.

But if you don’t want to wait for the final part, here are four useful starting points.

1. Make protein part of your first meal of the day.

Aim for around 30g of protein at breakfast or your first meal, adjusting that amount to suit your individual needs.

2. Include protein in your main meals.

Rather than consuming most of your protein at dinner, consider distributing it more evenly throughout the day.

3. Look at your total daily intake.

For many active adults, around 1.2–1.8g of protein per kilogram of body weight per day is a useful starting range. Your needs may differ according to your age, health, activity and goals. Consider both your daily total and the amount you consume at each meal.

4. If you’re vegetarian or vegan, plan your protein intake thoughtfully.

Choose a variety of protein-rich plant foods and pay attention to portion sizes and protein quality. A soya or pea protein isolate can be a convenient addition if you’re struggling to meet your needs through food alone.

You don’t need to change everything at once. Start by understanding what you’re eating now, identify where the gaps are, and make changes that fit your life.

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If nutrition is an area of your health that you find confusing and you’d like some clarity, let’s talk.

I work with people to develop personalised nutrition plans that take account of their goals, lifestyle, food preferences and individual circumstances.

No one-size-fits-all answers. Just a practical approach to understanding what your body needs and making nutrition work harder for you.