The purpose of the study was to examine the distribution of macronutrient density patterns in relation to obesity. This was done in a sample of 323 Danish men and women aged 35-65 years, selected randomly from a larger population sample of adult Danes. Dietary reporting bias of energy and protein intake, in relation to body fat percentage, was assessed by comparing intake data from a diet history interview with data estimated from PABA-validated 24-hour nitrogen excretion and estimated 24-hour energy expenditure. The results of the study showed that degree of obesity was positively associated with protein underreporting of total energy and protein, whereas compared with total energy reported, protein was overreported by the obese subjects. These associations were evident despite control for gender, age and smoking (p = 0.0003). In conclusion, errors in dietary reporting of protein seem to occur disproportionately with respect to total energy, suggesting a differential reporting pattern of different foodstuffs. Although, on average, all subjects over-reported energy percent from protein, over-reporting was most common in obese. It may therefore be speculated that snack type foods are preferentially forgotten when dietary omission occurs in obese individuals. The results of the present study seem in agreement with the general assumption that obese subjects tend to specifically under-report fat and sugar-rich foods, rather than generally under-report their total intake. These results may have wide implications for the interpretation of studies of diet and comorbidities to obesity.