Overweight and obese patients may develop paradoxical nutritional deficiency from eating high-energy foods with a poor nutrient content. In such patients, this condition is probably under-recognised, and thus untreated. The nutrient density of foods has recently been defined by a score--the naturally nutrient-rich (NNR) score--which assesses the contribution a food makes to the nutrient intake of a 2000 calorie (8360 kJ) daily diet and includes 14 key macronutrients. NNR foods are whole foods that provide the highest nutrient-to-kilojoule ratio. An awareness of the importance of the nutrient density of foods can assist health practitioners to recognise and effectively manage paradoxical nutritional deficiency. Knowledge of the nutrient density of foods helps people wanting to reduce their kilojoule intake to maintain a nutritionally sound diet, providing adequate vitamins, minerals and macronutrients.