Nuts are considered an energy-dense (and a nutrient-dense!) food. So how many kilojoules do they contain? And is the energy-density of nuts a problem?

What is energy density?

Energy density is the amount of energy (or kilojoules) in a specific weight of food. Energy-dense foods are high in kilojoules, compared to low energy-dense foods. 

Energy density is determined by the proportion of protein, fat, carbohydrates, fibre, alcohol and water in a food.

Foods that are high in fat can be particularly energy-dense. This is because fat contains the most kilojoules per gram, compared to protein, carbohydrate and alcohol. So, given nuts contain on average around 65% fat, they are a classed as an energy-dense food.

How much energy do nuts contain?

A 2020 Nuts for Life audit found that, on average, raw nuts contained 816kJ, dry-roasted nuts 779kJ, and oil-roasted nuts 773kJ per 30g serve.

Nuts are nutrient-dense

Whilst energy-dense, nuts are also nutrient dense!

This means they are packed with nutrients and bioactive substances, essential for good health. This is very different to, for example, biscuits and confectionery, which are also described as energy dense, but offer little in terms of beneficial nutrients.  

Nuts and weight

Despite being energy-dense, due to the healthy fats they contain, nut intake has been linked with a redued riks of overweight and obesity. And research shows that regularly eating nuts is associated with a reduced body weight, body mass index (BMI) and waist circumference [1-3].

One of the reasons for this is that we may not actually absorb up to 30 per cent of the kilojoules in nuts!

The results of carefully-controlled feeding trials, over the past decade, suggest that some of the fat in nuts is ‘trapped’ in the fibrous cell wall of the nut, making it hard for the body to digest and absorb [4-7]. Instead, nut eaters excrete some of this dietary fat in their stools – without it ever being used by the body as a source of energy.