What is Calorie Density
Calorie density (also called energy density) is a measure of the number of calories contained in a given weight of food. Calorie density is often expressed in the number of calories per 100g (3.5 ounces). Low calorie density foods contain fewer calories per 100g than high calorie density foods.
The sources of calories in the diet are the three main macronutrients: fat, protein and carbohydrate. Fat is the most calorie dense macronutrient containing around 900 calories per 100g, with protein and carbohydrate both containing around 400 calories per 100g. Alcohol is another substance that provides calories, containing around 700 calories per 100g.
High Calorie Density Foods
High calorie density foods contain a lot of calories per 100g. The highest calorie dense foods are pure oils and fats since they contain the most calories possible per unit of weight at around 900 calories per 100g. Butter is not quite as calorie dense as pure oils since butter is made up of around 16-18% water, which doesn’t contain calories, so butter contains a little over 700 calories per 100g.
Foods that contain high amounts of fat or oil tend to be very calorie dense. For instance, potatoes contain around 70 calories per 100g, however potato chips (crisps) made with potatoes and oil can contain over 500 calories per 100g.
Ultra processed foods, which are foods that are highly processed also tend to be on the high end of the calorie density spectrum. These foods are generally made from refined grains, sugars and fats or oils along with salt and other additives. They are usually low in water and fibre content, which are two food components that don’t contain calories, so the end product is more calorie dense.
High Calorie Density Foods list:
- Oily snacks – such as potato chips (crisps)
- Fast foods: such as french fries (chips), pizza and burgers
- Convenience foods – such as candy, pastries and cookies
- High fat condiments – such as mayonnaise and oil based dressings
- Fatty meats and processed meats – such as fatty cuts of beef, lamb, sausages and bacon
- High fat dairy products – such as butter and cheese
- High calorie beverages – such as sugar sweetened soft drinks
- Nuts – although high in fat, these tend to be the healthier unsaturated fats
Low Calorie Density Foods
Low calorie density foods contain a relatively low amount of calories per 100g. The lowest calorie density foods are green vegetables followed by fruits. This is due to the very high water content of these foods and because they also contain fibre. Some vegetables and fruits are made up of over 90% water, with many more being at least 80% water. Celery is an example of a very low calorie dense food and contains around 14 calories per 100g. This means that pure fat or oil is around 60 times as calorie dense as celery.
Low calorie density foods list:
- Green and yellow vegetables – non-starchy vegetables such as celery, cucumber, lettuce, eggplant (aubergine), tomatoes, peppers, onions and lettuce. These foods are on the lowest end of the calorie density spectrum
- Fruits – Fruits are a low calorie density food and mostly tend to vary in calorie density from around 30 to 60 calories per 100g. Watermelons are on the lower end of the fruits calorie density scale containing around 30 calories per 100g. On the high end of the fruit calorie density scale, bananas contain around 90 calories per 100g.
- Starchy vegetables – such as carrots, potatoes and sweet potatoes. Despite what some people think, potatoes are not a calorie dense food, containing around 70 calories per 100g. it’s often the way potatoes are served (eg fried in oil as french fries) that leads to this reputation.
- Low calorie beverages – such as coffee, tea, water or beverages sweetened with artificial sweeteners.
Calorie Density and Weight Loss
High calorie density does not automatically mean that foods are unhealthy, although it is often the case that unhealthy foods are high in calorie density. Nuts are an example of a calorie dense healthy food. Lots of studies show that an increased consumption of nuts is linked to an increase in several health outcomes.
Calorie density may be an important measure when it comes to weight loss. Research has shown that we tend to eat a similar weight of food on a daily basis. Although appetite and satiety (feeling full) are complex mechanisms, there are stretch receptors in the lining of the stomach that signal to the brain when we have taken in a certain volume of food, and these signals are factors in telling the brain that we have had enough to eat.
One such study on calorie density (or energy density) involving 9,551 adults calculated the energy density of different foods and found that both men and women who were classified as lean reported a higher proportion of dietary calories from low or very low energy density foods than those who were classified as obese. On the other hand, those participants who were classified as obese, reported a higher intake of calories from high energy dense foods than those who were classified as lean.
If we can lower the calorie density of the food we eat on a daily basis, and we naturally consume the same weight of food, then logically we will consume less overall calories.
Several studies have shown that pre-loading a meal with a low calorie density starter and then eating the main meal without restriction, resulted in less overall calories being consumed by those who ate the low calorie density starter than by those who only ate the main meal.
Lowering the overall calorie density of our diets may provide a useful tool if you wish to lose weight. This is likely to involve adding more low calorie density fruits and vegetables to your diet and trying to avoid foods that are high on the calorie density spectrum. This can also involve swapping higher calorie density foods such as fatty or processed meats to more moderate calorie density foods that are leaner sources of protein such as lean meats or plant sources of protein such as lentils.
Since many high calorie density foods are also not the healthiest, such as highly processed foods, processed meats and deep fried foods, this may also help to increase overall health as well.