Protein Intake
Also known as dietary protein, macros
The one macronutrient worth actively tracking. It determines whether weight loss makes you leaner or just smaller.
Whole foods vary. Protein powder $30–80/month if used.
How it works
Dietary protein supplies amino acids for muscle protein synthesis. During an energy deficit, adequate protein preserves lean mass by offsetting the increased protein breakdown. It also has the highest thermic effect of the macronutrients and is the most satiating, which improves adherence. Keratin and collagen are protein structures, so severe deficiency shows up in hair and nails.
How it's used
1.6–2.2g per kg of bodyweight daily is the well-supported range for people training; the upper end matters most during a deficit. Distribute across 3–4 meals of roughly 0.4g/kg each. Whole food sources first; whey or plant protein powder is a convenience, not a requirement.
Trade-offs
In favour
- Preserves muscle during fat loss — the difference between looking lean and looking deflated
- Most satiating macronutrient, which helps adherence
- Supports hair and nail structure
- Well-tolerated across a wide intake range
Against
- Requires some tracking to hit consistently
- Higher-protein foods cost more
- Marginal returns above roughly 2.2g/kg
Risks and side effects
- Pre-existing kidney disease requires medical guidance on protein intake
- Very high intakes can displace other nutrients
- Protein powders are loosely regulated — choose third-party tested products
How good is the evidence?
Extensive meta-analytic evidence for protein intake, lean mass retention and satiety.
Sources
Sources point to guideline bodies and literature searches rather than single papers, so they stay accurate as the evidence moves.