The key takeaway
Calorie density is energy per weight of food. Lower-density foods can add volume; concentrated foods still have a place.
What calorie density means
Compare the energy in an equal food weight, usually 100 g. Foods with a lot of water often provide less energy per gram. Foods rich in fat tend to provide more.
Our homepage uses an illustrative comparison: at 600 kcal per 100 g, about 17 g of peanut butter supplies 100 kcal; at 16 kcal per 100 g, cucumber supplies about 100 kcal in 625 g. Exact values depend on the product and dataset. This is an arithmetic example, not a laboratory analysis of a specific product.
Volume is not the whole story
Peanut butter and cucumber are not nutritional substitutes. They provide different nutrients and neither is a complete meal. Fullness is affected by the whole meal, your needs and your eating experience.
Do not use this concept to eat only the lowest-calorie foods. Adequate energy, protein, dietary fat and food variety still matter.
Use addition as a starting point
Add vegetables to a pasta sauce, fruit to a breakfast bowl or beans to a soup. Keep the ingredients that make the meal satisfying and enjoyable.
Look at a familiar recipe
Choose one meal and think about where extra vegetables or a pulse could fit naturally. Make that adjustment first, rather than shrinking every part of the meal.
Put it into practice
Sources & further reading
These sources support the general information and explain the wider context. Practical examples are illustrative.
- UK Government: Composition of foods integrated dataset (CoFID)
- NHS: The Eatwell Guide
- NHS: Facts about fat
General educational information for adults. Estimates are not a diagnosis or a personalised diet. For pregnancy, breastfeeding, eating-disorder concerns, medical conditions or medication-related questions, seek qualified guidance. Read the full disclaimer.