MACRONURTIENTS

Macronutrients

Nutrients needed in large amounts: carbs, lipids, proteins; provide energy.

Energy per gram: Carbs

4 calories per gram.

Energy per gram: Protein

4 calories per gram.

Energy per gram: Fat

9 calories per gram.

Main energy source for the body

Carbohydrates.

Only fuel the brain can use

Glucose (a carbohydrate).

Fiber

A carbohydrate that is not digested; provides 0 calories.

Simple carbohydrates

Quickly digested sugars that spike blood sugar.

Complex carbohydrates

Slower‑digesting carbs; steadier blood sugar.

Glycemic Index (GI)

Rates how fast a carb raises blood sugar.

Low GI foods

Raise blood sugar slowly; healthier for diabetics.

Glycemic Load (GL) formula

(GL) = (GI × carbs per serving) ÷ 100.

Why GL matters

Shows real blood sugar impact of a food.

Lipids

Non‑polar molecules: fats, phospholipids, sterols.

Triglycerides

Main energy storage lipid.

Phospholipids

Make up cell membranes.

Cholesterol (sterol)

Needed for membrane stability and steroid hormones.

Why fat is important

Needed for vitamins A, D, E, K absorption + hormone production.

When fat is used for energy

Low or moderate activity.

Saturated fat

Solid at room temp; no double bonds.

Unsaturated fat

Liquid at room temp; has double bonds.

Trans fats

Artificial fats; increase LDL and decrease HDL; very unhealthy.

HDL

“Good cholesterol”; carries cholesterol away from arteries.

LDL

“Bad cholesterol”; deposits cholesterol in arteries.

Proteins

Chains of amino acids folded into 3D shapes; perform most body functions.

Amino acids

Building blocks of proteins.

Polypeptide

Chain of amino acids before folding.

Protein

Folded polypeptide with a specific function.

Essential amino acids

Must be eaten; body cannot make them.

Non‑essential amino acids

Body can make them.

PDCAAS

Measures protein quality based on amino acid content.

Complementary proteins

Two foods that combine to make a complete amino acid profile (ex: rice + beans).

Why protein isn’t main energy source

Body uses it to build and repair, not fuel.

Phospholipids

Form cell membranes; hydrophilic head + hydrophobic tails.

Sterols

Cholesterol; used for hormones and membranes.

Triglycerides

Stored fat; long‑term energy.

Ghrelin

Increases hunger (“growling stomach”).

Leptin

Decreases hunger (“let’s stop eating”).

Insulin

Lowers blood sugar; signals fullness.

Glucagon

Raises blood sugar.

Monosaccharide

Single sugar molecule (glucose, fructose).

Disaccharide

Two sugars linked (lactose, sucrose).

Polysaccharide

Many sugars linked (starch, glycogen, fiber).

Lactose

Milk sugar; requires lactase enzyme to digest.

Lactose intolerance

Low lactase enzyme; lactose not digested.

Omega‑3 fatty acids

Healthy unsaturated fats; reduce inflammation.

Omega‑6 fatty acids

Essential but overconsumed; can increase inflammation.

Hydrogenation

Process that creates trans fats.

High GI foods

Cause fast blood sugar spikes.

Low GI foods

Cause slow, steady blood sugar rise.

Why fiber helps digestion

Adds bulk; slows sugar absorption.

Complete protein

Contains all essential amino acids (ex: meat, eggs).

Incomplete protein

Missing some essential amino acids (ex: beans, rice).

How many calories in 12 g fat?

12 × 9 = 108 calories.

How many calories in 30 g carbs?

30 × 4 = 120 calories.

How many calories in 10 g protein?

10 × 4 = 40 calories.

GL example: GI = 50, carbs = 20 g

(50 × 20) ÷ 100 = 10 GL.