What are macros?

The short answer

Macros are the three nutrients your body needs in large amounts and that provide calories: protein, carbohydrate and fat. Protein and carbohydrate each provide about 4 calories per gram, and fat provides about 9. Alcohol is not a nutrient you need, but it also provides about 7 calories per gram. Every food is some mix of these, along with water, fibre, vitamins and minerals.

Understanding macros helps you see why two foods with the same calories can affect hunger, energy and your goals in different ways.

Calories per gram

This is why food labels can work out calories from macros. A food with 10 grams of protein, 20 grams of carbohydrate and 5 grams of fat contains roughly 40 + 80 + 45, or about 165 calories.

What each macro does

Protein

Protein provides the building blocks your body uses to make and repair tissues, including muscle, skin and enzymes. It is also linked to feeling full after meals. Common public guidance for healthy adults is around 0.75 to 0.8 grams per kilogram of body weight per day, and many active people aim higher. Our guide to how much protein you need goes into the detail.

Carbohydrate

Carbohydrate is the body's main source of quick energy, and the brain relies heavily on glucose. Carbohydrates include starches in foods like bread, rice and potatoes, sugars in fruit, milk and sweets, and fibre. Fibre is a type of carbohydrate that your body does not fully digest, and it is linked to better digestion and fullness. Wholegrain and less processed carbohydrate foods usually bring more fibre and nutrients.

Fat

Fat provides energy, helps your body absorb vitamins A, D, E and K, and is needed for many body functions. Because it has more than twice the calories per gram of protein or carbohydrate, small amounts of fatty foods add up quickly. Public guidance generally recommends favouring unsaturated fats, found in olive oil, nuts, seeds, avocado and oily fish, and limiting saturated fat.

How much of each?

There is no single perfect split. Public guidance gives wide, flexible ranges. For example, the US National Academies describe acceptable ranges for adults of about:

• Carbohydrate: 45 to 65 percent of calories.
• Fat: 20 to 35 percent of calories.
• Protein: 10 to 35 percent of calories.

Within those ranges, many eating patterns can be healthy. People often adjust their split for personal preference, activity or goals. For instance, someone focused on building muscle may eat more protein, while an endurance athlete may need more carbohydrate.

A worked example

Imagine a daily target of 2,000 calories with 25 percent protein, 45 percent carbohydrate and 30 percent fat:

• Protein: 25% of 2,000 is 500 calories, divided by 4, or about 125 grams.
• Carbohydrate: 45% of 2,000 is 900 calories, divided by 4, or about 225 grams.
• Fat: 30% of 2,000 is 600 calories, divided by 9, or about 67 grams.

This is just an illustration. Your own targets depend on your calorie needs and goals.

Macros on a plate

You do not need to calculate grams to eat a good balance. A simple visual approach many people use is to fill around half the plate with vegetables or salad, a quarter with a protein food, and a quarter with a starchy carbohydrate, plus a small amount of healthy fat such as olive oil, nuts or avocado. This naturally gives a reasonable mix of all three macros with plenty of fibre.

Do you need to track macros?

Not everyone does. Tracking macros can be useful if you have a specific goal, such as hitting a protein target or balancing carbohydrates around training. For many people, simply knowing roughly which foods provide which macros is enough. If you want to try, our beginner's guide to tracking macros explains how to start simply, and reading a nutrition label shows where to find the numbers on packaged food.