Nutrient density

Nutrient density expresses the vitamins, minerals, protein and fibre a food supplies relative to its energy content. Leafy vegetables, offal, fish, eggs, pulses and berries score high; refined snacks and sweetened drinks deliver energy with very little else.

It matters most when calories are limited. In a deficit there is less room for anything that is not doing nutritional work, so micronutrient adequacy depends increasingly on what the remaining calories are spent on. It is also the concept behind the phrase 'overfed and undernourished'.

In practice no single scoring system is authoritative — several exist and they disagree at the edges, particularly about fat. The usable version of the idea is simple: build meals around whole foods that bring something besides energy, and treat the rest as the discretionary remainder.