What is energy density and why is it important?
Energy density means the amount of energy per weight of food, so think number of calories per mouthful or per pound. A high energy density diet tends to lead to weight gain, while a low energy density diet tends towards weight loss.
One of the main reasons for this is that people tend to eat the same quantity of food in terms of weight most days, so it makes sense that if we eat mainly foods that contain a high number of calories per mouthful or per pound then we are likely to eat more, while if we eat foods containing few calories per pound then we will eat fewer calories overall.
Low energy density foods
Foods containing the lowest energy density are unsurprisingly fibrous vegetables including salad leaves, asparagus, broccoli, cauliflower, green beans, peppers, mushrooms and onions among others. Next are the low carbohydrate fruits like berries, then starchy vegetables and sugary fruits. Foods at this low energy density can be eaten freely without fear of gaining weight. They contain large quantities of fibre and water and help to keep us full.
Beans and legumes and whole grains have a higher energy density than fruits and vegetables, but they are still relatively low. Dairy and meat substitutes, e.g. plant milks, quorn and tofu are in an energy density range that is still compatible with weight loss and can be useful sources of plant based proteins. Eat these in moderation!
Foods with higher energy density
Moving up the energy density ladder, breads and other baked goods can be enjoyed when we are losing weight but should be eaten less often than the aforementioned foods. Nuts and seeds have an even higher energy density but are sources of healthful fats, so we recommend them, but in small amounts. Oils and spreads have the highest energy density of all, and we suggest avoiding these where possible. This is one of the reasons why we would recommend olives but not olive oil, for example.
What to eat
Obviously it would be inappropriate to exist entirely on a diet of just fibrous vegetables and berries! Eating a mixture of foods with different energy densities so that the energy density of the meal overall is low is a good approach, think legumes and whole grains in reasonable quantities with plenty of lower density fruits and vegetables to add a lot of bulk without adding many calories.
By Dr Sue Kenneally
Stelmach-Mardas M, Rodacki T, Dobrowolska-Iwanek J, Brzozowska A, Walkowiak J, Wojtanowska-Krosniak A, Zagrodzki P, Bechthold A, Mardas M, Boeing H. Link between Food Energy Density and Body Weight Changes in Obese Adults. Nutrients. 2016 Apr 20;8(4):229. doi: 10.3390/nu8040229. PMID: 27104562; PMCID: PMC4848697.