Nearly all of us have heard of fats, carbohydrates and protein, but you could be forgiven for not knowing what each one does and how much we should consume of each. Read on for a brief guide to macronutrients and what they mean for you and your goals.

Key takeaways

• Macronutrients are essential nutrients that we need in large amounts: fats, carbohydrates and protein. 
• Each macronutrient plays different roles in the body:
  • Protein helps build and repair lean body mass.  
  • Dietary fats are a vital energy source and key for hormonal health. 
  • Carbohydrates are an energy source and important for performance.
  • There is a difference between the total weight of a food and its macronutrient content. 

Macronutrients

Macronutrients are types of nutrients that your body needs in large amounts, and you may well be familiar with the three main types: protein, fat and carbohydrate. On top of performing several other important roles, each macronutrient provides your body with a certain amount of energy:

Protein

The main role of protein in the body is structural, which means that your body uses it to build, maintain and replace substances like muscles, bones, connective tissue, hormones, enzymes, skin, hair and nails.

While protein’s primary role is not to provide energy, it contributes around 5-10% of your daily energy requirements when you are not eating in a deficit.

Gram for gram, protein is the most satiating (filling) macronutrient, which can indirectly help fat loss by making it easier to stick to a calorie-restricted diet.

Protein has a much higher thermic effect than fat and carbohydrate (20-30% versus 1-5% and 5-10% respectively). This means that, for every 100 kCal of protein you consume, your body burns 20-30 kCal through digestion.

There is a common myth that eating a high-protein diet “boosts your metabolism”. While maintaining and building muscle tissue does raise your energy requirements, this does not make protein a “free food”, as 70% of the total calories remain for use or storage.

Dietary fat

The main role of fat is to provide energy, a job for which it is well equipped. A single gram of fat provides 9 kCal of energy, which is more than twice the amount available from an equivalent quantity of protein or carbohydrate.

Dietary fat can help suppress hunger between meals, as it takes a relatively long time to digest and clear from your stomach. However, this effect is not immediate, and you can very easily consume a lot of calories from fat sources in a single meal.

Dietary fat supports important biological functions, such as transporting fat-soluble vitamins (vitamin A, D, E and K) and hormone production (there is research linking very low-fat diets to decreases in testosterone level – unfortunately, high-fat diets do not boost testosterone!).

Low-fat diets (think white fish and chicken) can be bland and boring. In contrast, fat-rich foods (think steak and nuts) add flavour and texture to your diet.

Dietary fat provides two specific types of fatty acids – omega-3 and omega-6 – which are essential nutrients. These nutrients are essential for optimal health, and we can only obtain them through our diet.

Carbohydrates

Like fat, the main role of carbohydrate is to provide energy, especially during high-intensity exercise, such as resistance training. Unlike protein and fat, carbohydrate is not an essential macronutrient, and you technically do not require any to survive. Nevertheless, many experts consider carbohydrates to be ‘conditionally essential’ for maximising performance in high-intensity exercise.

In practical terms, aiming for zero grams of carbohydrate is unrealistic due to trace amounts contained in fat-rich foods, fruit and vegetables. As with low-fat diets, low-carbohydrate diets can be restrictive in terms of food options and therefore difficult to sustain long-term. A specific type of carbohydrate, fibre, is vital for digestive health.

Macronutrients vs Foods

It is important to be aware of the difference between:

The total weight of the food you believe to be a good source of a macronutrient, and the amount of protein, fat and carbohydrate it contains per serving.

Many people think of foods as being 100% protein, fat or carbohydrate but there are very few single macronutrient foods. Apart from certain confectionary items (which are pure carbohydrate) and oils (which are pure fat), most foods consist of at least two macronutrients.

Almost all foods contain at least some water, which adds to the total weight. You can find the individual macronutrient and calorie content of a food or drink by looking at the nutrition label or by searching using the U.P. app.