Protein Sources: Complete Guide to Animal and Plant Proteins

Protein is having a moment. Every food screams "high protein!" But what actually matters? How much do you need? And which sources are best? Here's the complete, unbiased guide.

Why Protein Matters

Protein provides amino acids that your body uses for:

Building and repairing muscle
Making enzymes and hormones
Supporting immune function
Maintaining skin, hair, nails
Satiety (feeling full)
Preserving muscle during weight loss
Recovery from exercise

Your body can't store protein like fat or carbs—you need consistent daily intake.

How Much Protein Do You Need?

General Guidelines

| Goal | Protein (per kg body weight) | Example (150 lb/68 kg person) | |------|------------------------------|-------------------------------| | Sedentary adult | 0.8 g/kg | 54 g/day | | Active adult | 1.0-1.2 g/kg | 68-82 g/day | | Building muscle | 1.6-2.2 g/kg | 109-150 g/day | | Weight loss (preserving muscle) | 1.2-1.6 g/kg | 82-109 g/day | | Athletes | 1.4-2.0 g/kg | 95-136 g/day | | Older adults (60+) | 1.0-1.2 g/kg | 68-82 g/day |

Per Meal

Aim for 25-40g per meal for optimal muscle protein synthesis. Spreading intake throughout the day beats one large serving.

Complete vs. Incomplete Proteins

Proteins are made of 20 amino acids. 9 are essential (body can't make them):

Histidine, Isoleucine, Leucine, Lysine, Methionine
Phenylalanine, Threonine, Tryptophan, Valine

Complete proteins: Contain all 9 essential amino acids in adequate amounts

All animal proteins
Soy, quinoa, hemp seeds, buckwheat

Incomplete proteins: Low in one or more essential amino acids

Most plant proteins
Can combine to get all amino acids

Good news: You don't need complete proteins at every meal. Eating variety throughout the day provides all amino acids.

Animal Protein Sources

Chicken Breast

Per 3 oz (85g): 26g protein, 140 calories

✅ Lean, versatile, affordable ❌ Can be dry, less flavor

Best for: Building muscle, weight loss

Beef

Per 3 oz (85g): 22g protein, 180-250 calories (depending on cut)

✅ Complete protein, high in iron, zinc, B12, creatine ❌ Higher saturated fat (especially fatty cuts), environmental impact

Best for: Strength athletes, those with iron deficiency Choose: Lean cuts (sirloin, round, 90%+ lean ground)

Fish (Salmon)

Per 3 oz (85g): 22g protein, 175 calories

✅ Omega-3 fatty acids, vitamin D, complete protein ❌ Mercury concerns (some fish), cost

Best for: Heart health, brain function Choose: Wild-caught salmon, sardines, mackerel 2-3x/week

Eggs

Per large egg: 6g protein, 70 calories

✅ Complete protein, affordable, versatile, contains choline ❌ Cholesterol concerns (mostly debunked for most people)

Best for: Budget-friendly complete protein Note: Whole eggs > egg whites for nutrition

Greek Yogurt

Per cup: 17-20g protein, 100-150 calories (plain, nonfat)

✅ Probiotics, calcium, versatile ❌ Added sugar in flavored versions

Best for: Snacks, breakfast, gut health Choose: Plain, add your own fruit

Cottage Cheese

Per cup: 28g protein, 180 calories (low-fat)

✅ Highest protein dairy, casein (slow-digesting) ❌ Texture not for everyone

Best for: Before bed (slow release), high-protein snack

Turkey

Per 3 oz (85g): 25g protein, 125 calories (breast)

✅ Very lean, complete protein ❌ Can be dry

Best for: Lean protein without red meat

Plant Protein Sources

Tofu

Per cup: 20g protein, 180 calories

✅ Complete protein, absorbs flavors, versatile ❌ Processed, bland on its own

Best for: Plant-based muscle building Tip: Press to remove water, marinate for flavor

Tempeh

Per cup: 34g protein, 320 calories

✅ Complete protein, fermented (probiotics), whole food ❌ Stronger flavor, less versatile

Best for: Higher protein than tofu, gut health

Lentils

Per cup cooked: 18g protein, 230 calories

✅ High fiber, iron, affordable, no prep (red lentils) ❌ Incomplete protein (low in methionine)

Best for: Budget plant protein, soups and stews Pair with: Grains for complete protein

Chickpeas

Per cup cooked: 15g protein, 270 calories

✅ Fiber, versatile (hummus, roasted, in dishes) ❌ Incomplete protein, can cause gas

Best for: Snacks, salads, Mediterranean dishes

Black Beans

Per cup cooked: 15g protein, 230 calories

✅ Fiber, antioxidants, affordable ❌ Incomplete protein

Best for: Mexican dishes, bowls, soups Pair with: Rice for complete protein

Quinoa

Per cup cooked: 8g protein, 220 calories

✅ Complete protein, whole grain, versatile ❌ Lower protein than legumes

Best for: Grain replacement, salads Note: A carb source with protein, not a protein source

Edamame

Per cup: 17g protein, 190 calories

✅ Complete protein, fresh taste, fun to eat ❌ Soy concerns (largely unfounded)

Best for: Snacks, appetizers, salads

Hemp Seeds

Per 3 tbsp: 10g protein, 170 calories

✅ Complete protein, omega-3s, no prep ❌ Calorie-dense, expensive

Best for: Smoothies, salads, yogurt topping

Seitan

Per 3 oz: 21g protein, 120 calories

✅ Highest protein plant food, meat-like texture ❌ Made from wheat gluten (not for celiac), low in lysine

Best for: Meat replacement, stir-fries

Protein Supplements

Whey Protein

Per scoop (~30g): 20-25g protein

✅ Fast-absorbing, complete, supports muscle growth ❌ Dairy-based, some have additives

Best for: Post-workout, meeting protein goals easily

Casein Protein

Per scoop: 20-25g protein

✅ Slow-digesting (7 hours), reduces muscle breakdown ❌ Not for immediate post-workout

Best for: Before bed, between meals

Plant-Based Protein Powders

Per scoop: 15-25g protein

Options: Pea, rice, hemp, soy, blends

✅ Vegan-friendly, often complete when blended ❌ Some taste/texture issues, may need to try several

Best for: Plant-based athletes, dairy-free

Collagen Protein

Per scoop: 10-15g protein

✅ Supports skin, joints, gut ❌ NOT a complete protein (missing tryptophan), not for muscle building

Best for: Skin/joint health, NOT muscle building

Protein Quality Comparison

PDCAAS Score (Protein Digestibility Corrected Amino Acid Score)

Scale: 0-1, higher = better

| Protein | PDCAAS | |---------|--------| | Egg | 1.00 | | Whey | 1.00 | | Casein | 1.00 | | Soy | 1.00 | | Beef | 0.92 | | Pea protein | 0.89 | | Chickpeas | 0.78 | | Black beans | 0.75 | | Lentils | 0.63 | | Rice | 0.47 |

Note: Combining lower-scoring proteins improves overall quality.

Building High-Protein Meals

Breakfast (30-40g)

3 eggs + Greek yogurt + berries = 32g
Tofu scramble + tempeh bacon + toast = 38g
Protein smoothie (powder + Greek yogurt + milk) = 40g

Lunch (30-40g)

Chicken salad (4 oz chicken) + quinoa = 35g
Lentil soup (2 cups) + bread = 28g
Tuna (1 can) + chickpea salad = 38g

Dinner (30-40g)

Salmon (5 oz) + vegetables = 35g
Steak (4 oz) + roasted potatoes = 30g
Tempeh stir-fry (1 cup) + tofu = 45g

Snacks (10-20g)

Greek yogurt = 17g
Cottage cheese (1 cup) = 28g
Protein bar = 20g
Handful of almonds + string cheese = 12g
Edamame (1 cup) = 17g

High Protein on a Budget

Most affordable sources:

Eggs (~$0.15 per 6g protein)
Canned beans (~$0.10 per 7g protein)
Dried lentils (~$0.08 per 9g protein)
Chicken thighs (~$0.20 per 8g protein)
Greek yogurt (store brand) (~$0.15 per 5g protein)
Tofu (~$0.15 per 10g protein)

Budget tips:

Buy whole chickens, portion yourself
Canned fish (tuna, salmon)
Buy Greek yogurt in large tubs
Dried beans vs. canned (cheaper, more prep)
Eggs over bacon/sausage

Common Protein Mistakes

All protein at dinner — Spread throughout day
Fear of plant proteins — Quality matters, but plants work
Protein bars as meals — Often candy bars with protein
Ignoring protein during weight loss — Most important time
Too much protein powder — Whole foods first
Not tracking — Easy to under-eat protein

The Bottom Line

Most people need more protein than they eat
Both animal and plant proteins work
Quality and variety matter
Spread intake throughout the day
Hit 25-40g per meal for muscle building
Whole foods first, supplements to fill gaps

"The best protein source is the one you'll actually eat consistently."

Pick proteins you enjoy, that fit your budget and values. Consistency beats perfection.