Why Protein Matters in a Healthy Diet

As a personal trainer, one of the most common nutrition questions I’m asked is about protein intake and how much protein the body actually needs.

Protein is an essential macronutrient that plays a key role in muscle growth, muscle maintenance, and overall health. There are thousands of different proteins in the human body, all made from combinations of just 20 amino acids.

Without adequate protein intake, the body may experience muscle loss, fatigue, slower recovery from exercise, and reduced strength. This is why consuming enough protein as part of a balanced, healthy diet is especially important for adults who exercise regularly or are over 30.

What Is Protein?

Protein is made up of amino acids, often referred to as the building blocks of the body. Almost every part of the body relies on protein, including muscles, skin, hair, organs, enzymes, and hormones.

Of the 20 amino acids, the body can produce some on its own. However, nine essential amino acids must come from food, as the body cannot make or store them. These essential amino acids are:

• istidine

• Isoleucine

• Leucine

• Lysine

• Methionine

• Phenylalanine

• Threonine

• Tryptophan

• Valine

A varied diet that includes different protein sources helps ensure these needs are met.

Why Is Protein Important?

Protein is involved in nearly every major function in the body. It supports:

• Muscle repair and muscle recovery

• Enzyme and hormone production

• Immune system function

• Cell signalling and nutrient transport

For anyone doing strength training, resistance exercise, or regular workouts, protein becomes even more important. Exercise causes small amounts of muscle breakdown, and protein provides the materials needed to repair and rebuild muscle tissue stronger than before.

This process is essential for building strength, maintaining muscle mass, and improving overall fitness, particularly as we age.

Best Sources of Protein in Your Diet

All foods contain some protein, but the amount and quality vary.

Complete Protein Sources

Complete proteins contain all nine essential amino acids:

• Meat, poultry, and fish

• Eggs

• Dairy products (milk, yoghurt, cheese)

• Soy products (tofu, tempeh, edamame, soy milk)

• Quinoa

• Buckwheat

These are especially useful for meeting daily protein needs efficiently.

Incomplete Protein Sources

Incomplete proteins can still make up a large part of a healthy diet:

• Nuts and seeds

• Legumes (beans, lentils, chickpeas)

• Vegetables (broccoli, spinach, asparagus)

• Wholegrains (brown rice, wholewheat bread)

Combining different plant-based protein sources throughout the day easily covers amino acid needs.

How Much Protein Do You Need?

This is one of the most searched questions online, and it’s also one of the most misunderstood.

Many fitness forums and social media posts recommend far more protein than the average person needs. While protein is important, more is not always better. Excess protein that the body doesn’t need contributes to overall calorie intake and, over time, can impact health if intake is consistently excessive.

Evidence-Based Protein Recommendations

• General adults (under 40):~0.75–0.8g of protein per kg of bodyweight

• Adults over 40:~1.0–1.2g per kg to help maintain muscle mass

• Regular exercisers and strength training:1.2–1.6g per kg of bodyweight

• Athletes or intense training phases:Up to 2.0g per kg (usually during heavy training or calorie deficits)

For most people who train regularly, around 1.4–1.6g of protein per kg of bodyweight is more than enough to support muscle growth and recovery.

How to Spread Protein Throughout the Day

For best results, protein intake should be spread evenly across meals rather than consumed all at once. The body can only use so much protein at a time for muscle repair.

If you miss your target one day, don’t panic. Long-term consistency matters far more than hitting a perfect number every day. Just refocus and start again tomorrow.