After 40: Why do you lose muscle? - what you can actually do about it

If you have noticed your clothes fit differently, your strength isn't what it used to be, or you get tired more quickly than you did ten years ago, you are not imagining it. Starting around age 30 and increasing after 40, your body begins to lose muscle mass in a process doctors call sarcopenia. The good news is that it is not a decline you must accept. It is mostly manageable. In many cases, it is reversible once you understand what is causing it.

What is actually happening after 40?

After age 30, most people lose 3–8% of their muscle mass per decade, and that rate increases after 40. By the time you're 70, total muscle loss can reach 15% or more if nothing is done to stop it. This is not a beauty issue. Muscle is active tissue; it burns calories, helps control blood sugar, supports joints and keeps you moving and independent. Losing it increases the risk of falls, fractures, weakness and chronic diseases like type 2 diabetes and heart disease.

Why you lose muscle?

Several factors come together as we age:

• Hormonal changes. Testosterone, oestrogen and growth hormone levels go down with age. All three are important for keeping muscle healthy.
• Slower protein production. Your body becomes worse at using the protein you eat to fix and build muscle, a situation known as "anabolic resistance."
• Less movement. Life gets busier; joints can be painful. Workouts often stop happening.
• Loss of motor neurons. The nerve cells that make muscles work decrease in number, and some fibres those that help with power and speed shrink or die.
• Term low-grade inflammation. Often called "inflammaging ", this can stop muscles from repairing and growing over time.

The warning signs

Muscle loss can be hard to notice at first. Common signs include:

• Feeling weaker when doing tasks (carrying shopping, climbing stairs)
• Slower walking speed
• Tired during activities that used to be easy
• Trouble standing up from a low chair or the floor without using hands
• Small changes in weight even when eating habits are the same

What actually works

1. Strength training is essential

Resistance training is the effective way to keep and build muscle. Aim for 2 to 3 sessions per week, working all muscle groups. You don't need to become a bodybuilder; squats, lunges, push-ups, rows and deadlifts (with dumbbells, resistance bands or just your body weight) are enough to tell your body to hold on to and build muscle.

Progressive overload is important: slowly increasing the weight, number of repetitions, or difficulty over time helps your muscles keep getting stronger.

2. Eat protein

Because the body becomes less good at using protein with age, you probably need more than you did in your 20s. Many experts suggest 1.2 to 1.6 grams of protein per kilogram of body weight each day for adults over 40 who're active. Spread out over meals rather than eaten all at once, since the body can only use so much at a time. Good sources include eggs, chicken, fish, dairy, beans and tofu.

3. Do some cardio

While strength training builds muscle, cardio helps the blood flow and energy production in muscles. A mix of activity (like walking or cycling) and occasional higher-intensity sessions supports both heart health and muscle health.

4. Get enough sleep

Muscle repair happens mostly during sleep when growth hormone is released. Not sleeping enough is linked to losing muscle and gaining fat.

5. Control inflammation

An anti-inflammatory eating plan. Full of vegetables, fruits, omega-3 fats and whole foods and lower in processed foods and sugar. Can help reduce the long-term inflammation that stops muscles from staying healthy.

6. Check your vitamins

Vitamin D is often low and has been linked to muscles. A blood test can show if you need more, and taking it if needed is simple and cheap. Getting calcium, magnesium and omega-3s also helps your muscles and bones.

You do not need a big change. A plan that works could look like:

• Monday, Wednesday, Friday: 30 to 40 minutes of strength training ( body)
• Tuesday, Thursday: 20 to 30 minutes of fast walking or cycling
• Every day: A meal or snack with protein at each time you eat and a regular sleep schedule

Consistency is more important than intensity. The people who keep their muscles the best into their 50s, 60s and beyond are not usually the ones who trained the hardest in their 40s. They are the ones who kept showing up.

In a nutshell

Losing muscle after age 40 is a problem, but it is not something you have to accept. Strength training, enough protein, good sleep and managing inflammation can slow, stop or even reverse much of the loss. The habits you build now do not just change how you look. They change how you move and live through the decades of your life.