← All topics
nutrition/macronutrients·A · strong·~1 min read

Macronutrients: the basics

Protein, carbs and fat provide energy: 4, 4 and 9 kcal per gram, alcohol 7. For muscle growthHypertrophy (muscle growth) A muscle getting bigger, mainly through thicker muscle fibres. More in the glossary →, enough protein and total calories matter most. How you split the rest between carbs and fat is fairly flexible.

// What the research shows

For adults, the US Institute of Medicine (2005) set broad ranges that cover energy needs while keeping chronic disease risk low: 45 to 65% of calories from carbohydrate, 20 to 35% from fat and 10 to 35% from protein. For lifters, protein is better calculated per kilogram of body weight: about 1.6 g/kg is enough for most (Morton et al., 2018). The ISSN position standPosition stand An official statement by a professional society summarising the evidence on a topic. More in the glossary → on diets (Aragon et al., 2017) concludes that a wide range from low-fat to low-carb can work similarly well for body composition. Fat loss is driven by a sustained calorie deficitCalorie deficit You take in less energy than you use. The body draws on its reserves. More in the glossary →, muscle gain by a surplus plus training.

energy per gramfat9 kcalalcohol7 kcalProtein4 kcalcarbs4 kcalExample: 80 kg, 2,600 kcal per dayprotein 130 g20 %fat 70 g24 %carbs 360 g56 %
Fig. · Energy per gram Fat provides more than twice as much energy per gram as protein or carbs. Below, the example from the text: protein first, then fat, carbs fill the rest.

// In practice

  • How to calculate: protein first (about 1.6 g per kg), then at least 20% of calories from fat, carbs fill the rest.
  • Example with 80 kg and 2,600 kcal: 130 g protein (520 kcal), 70 g fat (630 kcal) and about 360 g carbs (1,450 kcal).
  • Alcohol provides 7 kcal per gram but no nutrients. Half a litre of beer has about 200 kcal.

// Limitations & open questions

The Institute of Medicine ranges date from 2005 and apply to the general population. In 2024 the US Academies themselves suggested rethinking them. For individuals they are a rough guide, not an exact prescription.

// Sources

last reviewed: 2026-11-14

// More from Nutrition

nutrition/daily-proteinA · strong

Daily protein

Around 1.6 g of protein per kg body weight is enough for most people. Up to about 2.2 g/kg may still add a little.

nutrition/protein-per-mealC · limited

Protein per meal

The old rule that “anything over 20–30 g per meal is wasted” doesn't hold up.

nutrition/calculate-calorie-needsB · moderate

How to calculate your calorie needs

Your needs consist mainly of basal metabolic rate and movement. Equations like Mifflin-St Jeor give a good starting point, but are often 10% or more off for individuals. It only gets accurate when you watch your weight and food for a few weeks and adjust.

nutrition/calorie-deficitB · moderate

Building muscle in a calorie deficit

A deficit slows muscle gain but barely affects strength gains. At around 500 kcal per day, average lean mass gain drops to zero.