When trying to achieve weight loss or when trying to maintain body composition with reduced training (athletes who are in quarantine or athletes who are injured), knowledge about the energy density of foods can be extremely useful.
Energy density of macronutrients
Energy density is the amount of energy or calories in a particular weight of food and is usually presented as kcal/g. Some foods are very energy dense, other foods, usually foods that contain a lot of water and fibre have less energy per gram.
The macronutrients, carbohydrate, fat and protein have different amounts of calories per gram. Alcohol can add energy too.
Energy density of food
Because our foods contain different combinations of these nutrients, they differ vastly in their energy content or energy density. The concept of energy density of foods was popularised by the work of Barbara Rolls and James Stubbs in the 1990s and early 2000s. Their research shows that applying the concept of food energy density can help to guide choices and control hunger while being flexible enough to encompass preferences.
A small quantity of food that is rich in fat will have a very high energy content.
A small quantity of food that is rich in fat will have a very high energy content. Visual cues may not prevent a large intake of energy of such foods. A number of studies have shown that subjects tend to eat a similar weight of food regardless of the macronutrient composition (1). Stubbs and colleagues (1, 2) demonstrated that when subjects received a diet that contained 20%, 40%, or 60% fat and could eat ad libitum, the weight of the food that they consumed was the same. The total amount of energy consumed, however, was significantly different, with the higher-fat diets showing higher intakes. This also resulted in greater weight gain.
Photo from Barbara Rolls. 1575kcal in high energy density foods versus low energy density foods.
Outside of the lab...
This result is also observed in outside the lab. In a representative group of US adults, men and women reported eating a lower energy dense diet ate fewer calories yet consumed more food by weight than people who consumed higher density diets (3, 4, 5). Several large-scale longitudinal and cross-sectional studies involving thousands of participants and a number of review articles have clearly shown that a decrease in energy density results in an increase in energy intake, whereas an increase in energy density results in a decrease in intake (3).