Protein, you’re probably not getting enough...

Dr Matthew
Mar 2
5 min read

Protein is not a “muscle supplement.” It is a structural requirement for human physiology.

After water (which accounts for roughly two-thirds of total body mass), protein is the most abundant class of molecule in the human body. Approximately 15–20% of total body mass is protein. In practical terms, protein comprises more of your body than all other non-water compounds combined.

Protein is not confined to skeletal muscle. It forms:

Structural tissue (muscle, skin, hair, nails, connective tissue)
Immune complexes and antibodies
Digestive enzymes
Transport proteins
Many hormones
Cellular signalling machinery

Even when a hormone or neurotransmitter is not technically classified as a “protein,” it is synthesised from amino acids — the same building blocks that form proteins. Amino acids are therefore not optional nutrients; they are foundational substrates for physical and neurological function.

Adequate protein intake is not merely about preserving muscle mass. It supports metabolic health, immune competence, recovery capacity, cognitive performance, and long-term resilience.

Current Recommendations vs. Evidence

Traditional dietary guidelines commonly cite:

0.8–1.0 g/kg/day(depending on age and sex)

However:

Around 10% of Australian adults consume less than the minimum recommendation.
Average intake sits near ~95 g/day.
For an average male, this equates to ~1.1 g/kg/day.
For an average female, ~1.3 g/kg/day.

These figures meet minimal adequacy — not optimal intake.

Evidence-Based Targets

Research suggests higher intakes are more appropriate for health and performance.

General health and performance:1.2–1.6 g/kg/day (total body mass)

Muscle gain:

1.6–2.2 g/kg/day (total body mass)
2.3–2.7 g/kg/day (lean body mass)

Fat loss while preserving muscle:

2.3–3.1 g/kg/day (lean body mass)

Which Body Weight Should You Use?

Use total body mass if body fat levels are within a normal range.
Use lean body mass if body fat exceeds ~25% (men) or ~35% (women), or if already very lean.

Protein Distribution: Meal Timing

Recent research indicates:

There is no strict upper ceiling on protein utilisation in a single meal.
The stomach is physiologically designed to handle large, intermittent intakes.
Protein enhances satiety and reduces overall caloric drive.

That said, daily intake targets are often easier to achieve when distributed.

For example:

5 meals × 0.5 g/kg/meal may be more manageable than
2 meals × 1.3 g/kg/meal

There appears to be a per-meal maximal stimulation range for muscle protein synthesis of ~0.55 g/kg/meal, although total daily intake remains the dominant factor.

Practical takeaway:Hit your total daily protein target first. Distribution is secondary.

Kidney Function and High Protein Diets

This is frequently misunderstood.

For individuals with normal kidney function, higher protein intakes within the ranges described above are not harmful.

In mild to moderate chronic kidney disease (CKD), emerging evidence suggests higher protein intake may not accelerate progression and may even be protective in some contexts.

In advanced CKD (Stage 4+), protein restriction is often advised. However, this becomes a trade-off:

Preserving kidney function marginally, versus
Preserving muscle mass, strength, and dialysis resilience

Greater pre-dialysis muscle mass is associated with better outcomes once dialysis begins. This is a nuanced clinical discussion and should be addressed individually with a renal physician.

Ageing and “Anabolic Resistance”

From approximately age 30 onward, the efficiency of muscle protein synthesis gradually declines — a situation termed anabolic resistance.

Research suggests protein requirements increase by approximately 1–1.5% per year after the age of 30, to achieve equivalent muscle protein synthesis.

This is why older adults often require:

Higher per-meal protein doses
Higher total daily protein intake

Failing to adjust intake upward with age accelerates sarcopenia, metabolic decline, and frailty risk.

Practical implication:Aim toward the higher end of evidence-based ranges as you age.

Summary

Protein is not a bodybuilding nutrient. It is a structural, metabolic, and neurological substrate.

Minimum recommendations prevent deficiency. They do not optimise performance, body composition, or ageing trajectories.

For most healthy adults:

1.2–1.6 g/kg/day should be considered baseline.
Higher ranges are appropriate for muscle gain, fat loss, and aging populations.

Unless advanced kidney disease is present, higher protein intakes are not inherently harmful and are often physiologically advantageous.

The next discussion will address why protein requirements increase with age.

References:

Morton, Robert W., et al. "A Systematic Review, Meta-analysis, and Meta-regression of the Effect of Protein Supplementation on Resistance Training–Induced Gains in Muscle Mass and Strength in Healthy Adults." British Journal of Sports Medicine 52.6 (2018): 376-384.

Jäger, Ralf, et al. "International Society of Sports Nutrition Position Stand: Protein and Exercise." Journal of the International Society of Sports Nutrition 14.1 (2017): 20.

Schoenfeld, Brad J., and Alan A. Aragon. "How Much Protein Can the Body Use in a Single Meal for Muscle-Building? Implications for Daily Protein Distribution." Journal of the International Society of Sports Nutrition 15.1 (2018): 10.

Phillips, Stuart M., and Luc J. C. van Loon. "Dietary Protein for Athletes: From Requirements to Optimum Adaptation." Journal of Sports Sciences 29.s1 (2011): S29-S38.

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