Protein · Fat · Carbohydrates
The three macronutrients, explained properly
Everything your body does — building muscle, making hormones, fueling your brain — comes down to how you use protein, fat, and carbs. Built for nutrition students and anyone who wants the real biology, not the diet-culture version: what each macro actually does, what happens when you don't get enough, and exactly how much you need.
The three macronutrients
"Macros" is short for macronutrients — the three nutrients your body needs in large amounts for energy and to build and repair tissue. Each one plays a different, non-interchangeable role.
Building & repairing tissue
Made of amino acids, protein builds and repairs muscle, skin, and organs, and forms enzymes, antibodies, and hormones. 4 calories per gram.
FatHormones & cell structure
Dietary fat builds cell membranes, produces steroid hormones like testosterone and estrogen, and carries vitamins A, D, E, and K. 9 calories per gram.
CarbohydratesEnergy & glycogen
Carbs are your body's preferred fuel, stored as glycogen in muscle and liver and used directly by your brain. 4 calories per gram.
Why "just eat healthy" isn't specific enough
Calories tell you how much energy you're eating. Macros tell you what that energy is made of — and that composition affects muscle growth, hormone production, energy levels, and how full you feel. Two people eating the same 2,000 calories can have completely different outcomes depending on their protein, fat, and carb split.
That's why we built calculators that turn your body weight, activity level, and goal into concrete gram targets for each macronutrient, grounded in the same reference ranges used by dietitians and sports nutrition researchers.
Try the macro calculatorExplore each macronutrient
Every page below covers the biology, the warning signs of not getting enough, food sources, and cited references.
Protein →
Muscle protein synthesis, repair, RDA vs. athlete needs, and deficiency symptoms like kwashiorkor and muscle wasting.
Fat →
Hormone production, essential fatty acids, fat-soluble vitamins, and the real AMDR range for fat intake.
Carbohydrates →
Glycogen storage and depletion, brain fuel, fiber, and what happens on very low-carb diets.
For students
Studying for an exam, not just curious?
A 53-term glossary, 62 articles, and quizzes that explain exactly why an answer is right or wrong — built to make the material stick, not just summarize it.
62 articles
Every long-tail question, answered and cited.
4 quizzes
Instant explanations on every answer.