Macronutrients: protein, carbs, fat

The 3 macronutrients

Protein — amino acids. Building blocks for muscle, enzymes, hormones, immune function. Most satiating macro. Carbohydrate — primary fuel for high-intensity exercise. Stored as glycogen in muscle and liver. Spares protein from being used for energy. Fat — essential for hormones, fat-soluble vitamin absorption, cell membranes. Primary fuel at rest and low-intensity work.

Protein

For sedentary adults: 0.8 g/kg (~0.36 g/lb) — survival level. For active adults: 1.6-2.2 g/kg (~0.7-1.0 g/lb) — supports training and recovery. For fat loss: 1.8-2.4 g/kg (~0.8-1.1 g/lb) — preserves muscle in a deficit. Spread across the day: 20-50g per meal, 3-5 meals. Protein synthesis is maximally stimulated by ~30-40g per dose in most adults. Sources: chicken, beef, fish, eggs, dairy (Greek yogurt, cottage cheese), whey protein, soy, legumes (less complete amino acid profile).

Carbohydrates

For sedentary adults: 100-200g/day is fine. Higher if active. For active adults: 3-7 g/kg depending on training volume. Endurance athletes may need 8-12 g/kg. For fat loss: moderate carbs (100-200g/day) usually feel best for adherence. Very low-carb (<50g/day) works for some but isn't necessary for fat loss. Carb timing: training-day carbs around workouts help performance. Otherwise, total daily intake matters most. Sources: rice, oats, potatoes, fruit, bread, pasta. Choose whole-food sources mostly; refined carbs are fine in small amounts.

Fat

Minimum: 0.5-0.8 g/kg (~0.25-0.4 g/lb) — needed for hormonal function. Typical: 25-35% of total calories for most people. For low-fat dieting clients: don't go below 50g/day for women, 60g/day for men — hormones suffer. Sources: olive oil, avocado, nuts, seeds, fatty fish (omega-3s), eggs, full-fat dairy. Limit highly processed seed oils and trans fats.

A practical macro framework

For a 175lb active male, fat loss goal (1,800 kcal target):

Protein: 175g × 4 = 700 kcal
Fat: 60g × 9 = 540 kcal
Carbs: 140g × 4 = 560 kcal
Total: 1,800 kcal

For a 140lb active female, muscle gain goal (2,200 kcal):

Protein: 130g × 4 = 520 kcal
Fat: 70g × 9 = 630 kcal
Carbs: 263g × 4 = 1,050 kcal
Total: 2,200 kcal

Macros vs whole-food approach

For some clients, exact macros work. For others, hand-portion methods work better:

Palm of protein per meal
Cupped hand of carbs (more on training days)
Thumb of fat
Fist of vegetables

Both work. Pick the one the client will actually follow.

Common macro mistakes

Under-eating protein — the single most common mistake in fat loss programs. Demonizing carbs — carbs aren't the enemy. Total calories are. Going too low fat — hormonal disruption follows. 50g/day minimum. Counting only "clean" foods — calorie distortion. Tracking only some foods is worse than not tracking at all.

TL;DR

Protein: 0.7-1.0 g/lb for active adults. Carbs: scale with activity. Fat: 25-35% of calories, never below 50g for women or 60g for men. Pick a framework (macros or hand portions) the client will actually follow.