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What are macros?
Macros — macronutrients — are protein, carbohydrate and fat: the three parts of food that supply energy. Every calorie on a nutrition label comes from them (plus alcohol, if there is any).
The three macronutrients
Protein · 4 kcal/g Builds and repairs muscle, skin, enzymes and hormones. It is the most filling macro and costs the most energy to digest. Found in meat, fish, eggs, dairy, tofu, beans and lentils.
Carbohydrate · 4 kcal/g The body’s preferred fuel for the brain and hard exercise, stored as glycogen in muscle and liver. Found in grains, potatoes, fruit, beans and sugar. Fibre is a carbohydrate you mostly do not digest. Why a potato is packed with starch at all comes down to how plants store the sugar they make; ahaboo zooms into a leaf to show where that sugar is made.
Fat · 9 kcal/g Long-term energy storage, cell membranes, hormone production and absorption of vitamins A, D, E and K. Found in oils, butter, nuts, seeds, avocado, fatty fish and meat. More than twice the calories per gram of the other two.
Build a plate: grams in, calories out
Drag the grams of each macro and watch how the calories stack. Notice how little fat it takes to match a lot of protein.
435 kcal — protein 28%, carbs 41%, fat 31%
Weight on the plate (grams) and share of calories are different things: 15 g of fat and 34 g of protein carry the same 135 kcal.
Why count macros instead of just calories?
Two diets with identical calories can produce different results. With enough protein, more of the weight you lose is fat rather than muscle, and you feel fuller on the same calories. Carbs and fat are more interchangeable — split them the way that suits your training and appetite.
How much of each do you need?
- Protein: 1.6–2.2 g per kg of bodyweight if you train — calculate yours.
- Fat: 20–35% of calories, not less than about 0.6 g/kg — fat intake calculator.
- Carbs: the remainder — from under 50 g on keto to 6+ g/kg for endurance athletes — carb calculator.
The macro calculator puts all three together from your body and goal. When you are ready to start, read how to track macros.
Questions people ask
What are macros in simple terms?
Macronutrients are the three nutrients you eat in large amounts that supply energy: protein, carbohydrate and fat. Alcohol also supplies energy but is not a nutrient. “Tracking macros” means counting grams of each rather than calories alone.
How many calories are in a gram of each macro?
Protein 4 kcal, carbohydrate 4 kcal, fat 9 kcal, and alcohol 7 kcal per gram. These are the Atwater factors used on nutrition labels. Fibre supplies roughly 2 kcal per gram, which labels often ignore.
Are macros more important than calories?
Calories decide whether your weight goes up or down. Macros — especially protein — decide how much of that change is muscle versus fat, and how full and energetic you feel. Tracking macros tracks calories automatically.
What are micronutrients?
Vitamins and minerals, needed in milligrams or micrograms rather than grams. They supply no energy but are essential. Eating a variety of fruit, vegetables, whole grains and protein foods covers most of them.