What is energy density?
'Energy density' is the amount of energy (or calories) per gram of food. Lower energy density foods provide less energy per gram of food so you can eat more of them without consuming too many calories. So this is a good way to help control how much we eat, without going hungry and may also be a great new way to help you lose weight.
Low energy density foods include foods with a high water content, such as soups and stews, foods like pasta and rice that absorb water during cooking, and foods that are naturally high in water, such as fruit and vegetables. Foods that are high in fibre, such as wholegrain breads and cereals, and lower fat foods also tend to have a lower energy density. High energy density foods tend to include foods that are high in fat and have a low water content, for example biscuits and confectionery, crisps, peanuts, butter and cheese.
Studies have shown that people tend to consume about the same amount (weight) of food each day, but not necessarily the same amount of energy (or calories). So it is possible to trick ourselves into consuming less energy, without feeling hungrier, by eating a lower energy density diet, which still makes up the same weight of foods overall throughout the course of a day.
This is probably best illustrated with an example – the image here shows two portions of a fruit-based dessert – they are very different in size but actually both contain exactly the same amount of calories! The difference is that the one on the left has a low energy density, while the one on the right has a high energy density. Basically, by choosing the lower energy density option, you get to eat a lot more food for the same number of calories!
How is energy density calculated?
It is very easy to calculate the energy density of foods, all you need to know is the weight of a serving of the food (in grams) and the amount of calories that serving contains. The energy density of a food is the number of calories divided by the weight.
Energy density = no of calories/weight (grams)
So using the desserts above as an example, they both contain 215 calories, but the one on the left weighs 300g while the one on the right only weighs 140g. Therefore:
The energy density of the dessert on the left = 215 kcal/300g = 0.7
The energy density of the dessert on the right = 215 kcal/140g = 1.5
So although the two desserts both contain the same number of calories, the one on the left has a much lower energy density than the one on the right. By choosing foods with a lower energy density, this will help you to feel fuller without consuming too many calories.
Very low energy density foods = less than 0.6 calories/gram
Low energy density foods = 0.6 to 1.5 calories/gram
Medium energy density foods = 1.5 to 4 calories/gram
High energy density foods = more than 4 calories/gram
It is better to eat mostly foods that are very low, low or medium in energy density, and consume higher energy density foods in small amounts.
This doesn’t mean that high energy density foods cannot be included when eating a low energy density diet, as it is the overall energy density of the diet that is important - small portions of high energy density foods can be included alongside plenty of lower energy density foods.
- © British Nutrition Foundation 2009