The three building blocks of every meal — proteins, carbohydrates, and fats. Understanding how each works transforms how you eat.
Proteins
Role
Tissue building, enzyme production, immune function, hormone synthesis
Daily Target
0.8g/kg bodyweight (sedentary) to 2.2g/kg (athletes)
Food Sources
animal
plant
Key Concepts
Complete Protein
Contains all 9 essential amino acids in adequate amounts. All animal proteins are complete; most plant proteins are not (exceptions: quinoa, hemp, soy, amaranth).
Bioavailability
The proportion of protein your body can actually absorb and use. Animal protein averages 90-99% bioavailability; plant protein averages 70-90%.
Leucine Threshold
Leucine is the primary amino acid trigger for muscle protein synthesis. You need ~2-3g of leucine per meal to activate mTOR and build muscle.
Protein Timing
Distributing protein evenly across 3-4 meals (30-40g each) is more effective than consuming it all at once. Your body can only use ~0.4g/kg per meal for muscle synthesis.
Common Mistakes
Carbohydrates
Role
Primary energy source, brain fuel, glycogen replenishment, fiber for gut health
Daily Target
45-65% of total calories (varies by protocol)
Food Sources
complex
simple
fiber
Key Concepts
Glycemic Index (GI)
How quickly a carbohydrate raises blood sugar (0-100). Low GI (<55) provides steady energy; high GI (>70) causes spikes and crashes.
Glycemic Load (GL)
GI multiplied by actual carbohydrate amount. A more accurate measure — watermelon has high GI but low GL because it is mostly water.
Glycogen
Stored carbohydrate in muscles and liver (~400-500g total). Depleted by intense exercise; replenished by eating carbs within 2 hours post-workout.
Resistant Starch
Carbohydrates that resist digestion, feeding beneficial gut bacteria. Found in cooled cooked rice/potatoes, green bananas, and oats.
Fiber Types
Soluble fiber (dissolves in water, lowers cholesterol, feeds gut bacteria) vs insoluble fiber (adds bulk to stool, prevents constipation). You need both.
Common Mistakes
Fats (Lipids)
Role
Cell membrane structure, hormone production, brain health (60% fat), fat-soluble vitamin absorption, energy storage
Daily Target
20-35% of total calories
Food Sources
saturated
monounsaturated
polyunsaturated
Key Concepts
Omega-3 to Omega-6 Ratio
Historical ratio was 1:1; modern diets are 1:20 or worse. Too much omega-6 (seed oils) causes inflammation. Aim for 1:4 or better.
EPA & DHA
The two active omega-3 fatty acids. EPA reduces inflammation; DHA builds brain tissue. Plant sources (flax, chia) only provide ALA, which converts at <5% efficiency.
Smoke Point
The temperature at which an oil breaks down and creates harmful compounds. Use high-smoke-point oils (avocado, ghee) for cooking; save olive oil for low heat or raw.
Cholesterol
A molecule your liver produces (80% of total). Dietary cholesterol has minimal impact on blood cholesterol for most people. The LDL-to-HDL ratio matters more than total.
MCT Oil
Medium-chain triglycerides that bypass normal fat digestion, going directly to the liver for immediate energy. Found in coconut oil; popular in keto protocols.
Common Mistakes