Protein, carbs and fat: macronutrients explained simply

Almost every food you eat is built from three macronutrients: protein, carbohydrate, and fat. They are called macronutrients, or macros for short, because your body needs them in large amounts, measured in grams rather than the milligrams and micrograms used for vitamins and minerals. Understanding what each one does, and how many calories it carries, turns a confusing nutrition label into something you can actually read at a glance.

This guide keeps it simple. We will walk through what each macro does, the calories each one carries per gram, and how to use the macro breakdown that appears on every food page in our database.

Calories per gram: the number that ties it together

The single most useful fact about macros is how much energy each one carries. The values are fixed and worth memorizing:

• Protein: 4 calories per gram
• Carbohydrate: 4 calories per gram
• Fat: 9 calories per gram

Fat carries more than twice the calories of the other two, which is why fat-rich foods pack a lot of energy into a small portion. This is also the math behind every calorie count you see. Multiply the grams of each macro by its calories per gram, add them up, and you have the total energy in a food.

Protein: the building macro

Protein supplies the amino acids your body uses to build and maintain tissue, from muscle to skin to the enzymes that run everyday chemistry. It also tends to be filling, which is why protein-forward meals leave many people satisfied on fewer calories.

Lean animal foods are the most concentrated sources. Chicken breast, skinless, raw carries about 23 grams of protein per 100 grams with almost no carbohydrate, and it earns a Nutrient Density Score of 74. A wild Atlantic salmon fillet brings roughly 20 grams of protein per 100 grams alongside its fat. Plants contribute too: lentils deliver close to 25 grams of protein per 100 grams, which is unusual for a plant food and a big reason they score 70 on our scale.

Carbohydrate: the energy macro

Carbohydrates are your body's most convenient fuel. They range from simple sugars to the long starch chains in grains and beans, and the best carbohydrate sources also carry fiber, the part of the plant your body does not digest but that supports fullness and steady energy.

Whole-food carbohydrates are where the value lives. Oats are mostly carbohydrate and still score 65, thanks to their fiber and minerals. Lentils are a standout example of a food that is high in both carbohydrate and protein at once: about 63 grams of carbohydrate and nearly 11 grams of fiber per 100 grams, which is why they show up so often on nutrient-dense grocery lists. Refined carbohydrates tell the other side of the story. White rice, unenriched is almost pure starch with little fiber, and it scores just 39.

Fat: the concentrated macro

Fat delivers energy, helps your body absorb vitamins A, D, E, and K, and carries essential fatty acids you cannot make on your own. Because it holds 9 calories per gram, a little goes a long way, and fat-rich whole foods often score lower on a per-calorie scale even when they are genuinely good for you.

Salmon is the clearest index example: its fat is where its healthy oils live, and wild Atlantic salmon still scores 66. Almonds are fat-forward whole foods that manage a strong 80, while avocado lands at 66. Pure fats sit lower because they are all energy and little else: olive oil scores 34 despite being a staple of many healthy kitchens. None of these are bad choices. The score simply reflects that fat concentrates calories.

How to read macro balance on a NutriVerdict food page

Every food page shows the split of calories across protein, carbohydrate, and fat, not just the raw grams. That distinction matters. Because fat carries more than twice the calories per gram, a food can look balanced by grams yet be dominated by fat once you convert to calories. Reading the calorie split tells you what a food actually brings to your day.

The fastest way to see this in action is to combine foods. Open the plate builder, add real foods in the amounts you would eat, and watch the calorie split shift as you go. Pair a protein like salmon or chicken with a carbohydrate like lentils or oats, add a small amount of fat, and you can build a plate whose macro balance and Nutrient Density Score you can see instantly.