Protein Sources Compared

Protein is the only macronutrient that provides nitrogen — the essential element in amino acids that build and repair every tissue in your body. Beyond muscle, protein is required for enzymes, hormones (including insulin and growth hormone), immune antibodies, and transport proteins like haemoglobin.

Adequate protein supports:

• Satiety: Protein stimulates PYY and GLP-1 hormones that reduce hunger — more effectively than fat or carbohydrates.
• Muscle protein synthesis (MPS): Stimulated most effectively by 20–40 g of protein containing at least 2–3 g of leucine per meal.
• Thermic effect: Protein requires 20–30% of its calories just to digest, compared to 5–10% for carbs and 0–3% for fat.
• Bone density: Contrary to older beliefs, higher protein intake is associated with better bone mineral density.

The minimum RDA is 0.8 g/kg/day. Most researchers now recommend 1.2–1.6 g/kg for active adults and up to 2.2 g/kg for those pursuing muscle growth.

A complete protein contains all nine essential amino acids (EAAs) in adequate proportions. Most animal proteins and a handful of plant proteins meet this criterion. Incomplete proteins lack one or more EAAs in sufficient amounts but can be combined throughout the day to cover all requirements — the body pools amino acids over a 24-hour period.

Source type	Complete?	Limiting amino acid (if incomplete)	Protein quality score (DIAAS)
Whey protein	Yes	—	1.09 (excellent)
Egg (whole)	Yes	—	1.13 (excellent)
Beef	Yes	—	1.10 (excellent)
Chicken	Yes	—	~1.08 (excellent)
Soy / edamame	Yes	—	0.91 (high)
Lentils	No	Methionine	0.59 (medium)
Black beans	No	Methionine	0.62 (medium)
Wheat (bread)	No	Lysine	0.45 (low)
Rice	No	Lysine	0.59 (medium)

The DIAAS (Digestible Indispensable Amino Acid Score) is the most rigorous protein quality metric. Scores above 1.0 indicate excellent quality; 0.75–1.0 is good; below 0.75 is adequate but lower quality.

Animal proteins deliver complete amino acid profiles with high bioavailability and are especially rich in B12, heme iron, zinc, and creatine — nutrients rarely found in meaningful amounts in plants.

Food	Serving	Protein (g)	Calories	Protein kcal ratio	Notes
Chicken breast (cooked, skinless)	100 g	31 g	165 kcal	75%	Leanest common meat protein
Canned tuna (in water)	100 g	25 g	116 kcal	86%	Convenient, affordable
Greek yogurt (0%, plain)	170 g	17 g	100 kcal	68%	Also provides calcium and probiotics
Cottage cheese (1%)	226 g (1 cup)	28 g	163 kcal	69%	High in casein — slow digesting
Whole egg	1 large (50 g)	6 g	72 kcal	33%	Excellent leucine content
Salmon (cooked)	100 g	25 g	208 kcal	48%	Also provides ~2.2 g omega-3
93% lean ground beef (cooked)	100 g	26 g	218 kcal	48%	High in zinc and B12
Shrimp (cooked)	100 g	24 g	99 kcal	97%	Highest protein-to-calorie ratio

Tip: Vary protein sources throughout the week — different animals and cuts provide different micronutrient profiles. Salmon, eggs, and dairy complement each other's nutrient gaps.

Plant proteins are valuable for their fibre, phytonutrients, and lower saturated fat content. To match the anabolic effect of animal protein, consume slightly larger portions or prioritise sources with higher leucine content.

Food	Serving	Protein (g)	Calories	Complete?	Notes
Edamame (cooked)	155 g (1 cup)	17 g	188 kcal	Yes	Best plant protein-to-calorie ratio
Tofu (firm)	126 g (½ cup)	10 g	94 kcal	Yes	Versatile; absorbs flavour well
Tempeh	85 g	16 g	160 kcal	Yes	Fermented soy; higher iron than tofu
Lentils (cooked)	198 g (1 cup)	18 g	230 kcal	No	Combine with rice to complete profile
Black beans (cooked)	172 g (1 cup)	15 g	227 kcal	No	High fibre; good iron source
Chickpeas (cooked)	164 g (1 cup)	15 g	269 kcal	No	Excellent versatility
Hemp seeds	28 g (3 tbsp)	10 g	166 kcal	Yes	Complete; high omega-3 ALA
Seitan (wheat gluten)	85 g	21 g	104 kcal	No	Not suitable for gluten intolerance

Warning: Soy-based proteins (tofu, tempeh, edamame) are the only plant proteins with a DIAAS score comparable to many animal proteins. For muscle building on a plant-based diet, these should be your primary protein anchor.

The most reliable method is to build each meal around a clear protein source and pre-plan the day's total. A simple rule: aim for 25–40 g of protein per main meal — easier to track than a running gram total.

Target (g/day)	Sample day — animal-based	Sample day — plant-based
120 g	3 eggs + 2 egg whites (18g) + Greek yogurt (17g) + 150g chicken breast (46g) + 100g salmon (25g) + cottage cheese snack (14g)	Tofu scramble 20g + edamame 17g + lentil soup 18g + tempeh stir-fry 16g + hemp seeds + protein smoothie 20g

• Protein powder (whey, casein, pea, rice) is a practical top-up — not a replacement for whole food. One scoop typically delivers 20–30 g protein for 100–130 kcal.
• Distribute protein across 3–4 meals rather than loading it at dinner — each meal should deliver at least 20 g to maximally stimulate muscle protein synthesis.
• Track for two weeks then rely on portion intuition — most people consistently underestimate protein intake before tracking.

Tip: If you struggle to hit targets, replace a carbohydrate snack (crackers, fruit) with a protein-forward one (Greek yogurt, cottage cheese, hard-boiled eggs, edamame). This single swap often bridges a 20–30 g daily gap.