How Much Protein Do You Really Need? The Science, Simplified

"Eat 2g of protein per kilo of bodyweight every day" — you've heard it a thousand times. But where does that number come from, and is it actually backed by evidence?

The Official Numbers

The Australian Recommended Dietary Intake (RDI) for protein is:

• 0.84g per kg for adult men
• 0.75g per kg for adult women

That's roughly 63g per day for a 75kg male — enough to prevent deficiency, but nowhere near what's needed for muscle growth or athletic performance.

What the Research Actually Says

A 2018 meta-analysis published in the British Journal of Sports Medicine found that 1.6g per kg per day is the optimal intake for muscle hypertrophy in resistance-trained individuals. Benefits level off beyond 2.2g per kg — there's simply no additional muscle gain to be had.

That means:

• 60kg person: ~96g per day
• 75kg person: ~120g per day
• 90kg person: ~144g per day

Real-World Considerations

Activity Level Matters

Your training intensity and frequency affect protein needs. Endurance athletes need slightly less (~1.2–1.4g/kg), while strength athletes benefit from the full 1.6–2.2g/kg range.

Age Changes Things

Muscle becomes more "anabolically resistant" as you age. Adults over 60 should aim for the higher end of the range (1.6–2.0g/kg) to maintain muscle mass.

Timing Isn't Everything

The old "30g every 3 hours" rule has been largely debunked. Total daily intake matters far more than distribution, though spreading protein across meals (25–40g per meal) does seem optimal for muscle protein synthesis.

Hitting Your Target — Without the Hassle

A typical day with ~120g protein might look like:

• Breakfast: Greek yoghurt + oats + berries (~25g)
• Lunch: Chicken thigh + quinoa + veg (~35g)
• Snack: Protein shake (~24g)
• Dinner: Salmon + sweet potato + greens (~30g)

One scoop of whey protein (24g) makes hitting the target dramatically easier — especially on busy days.

The Bottom Line

For most active Australians:

• Minimum for muscle growth: 1.6g per kg
• Upper useful limit: ~2.2g per kg
• More than 2.5g per kg: No additional benefit, extra cost, potential kidney strain if you have pre-existing issues

Don't overthink it. Hit ~1.6g/kg, spread it across meals, and focus on training consistency instead of obsessing over spreadsheets.

Sources: Phillips & Van Loon (2011) Dietary protein for athletes; Morton et al. (2018) BJSM meta-analysis.