Under-reporting of food intake and body fatness in independent older people: a doubly labelled water study

Background: there are no accurate methods for the assessment of food intake in older populations, under-reporting of intake being highly prevalent. There is controversy about which dietary assessment method and what person's characteristics are associated with greater under-reporting rates. Objective: to assess the correlation between under-reporting of energy intake (EI) and different percentages of body fat in independent older people. Design: cross-sectional study. Settting: area assisted by the Family Health Program of the Ribeiro Preto Medical School, University of So Paulo, Brazil. Sujects: one hundred volunteers aged 60-70 years. Methods: all volunteers had their body composition assessed by dual-energy x-ray absorptiometry. In second phase, 41 volunteers were evaluated, representing the four quartiles of fat percentage. Total energy expenditure (TEE) was measured by the doubly labelled water method, and EI was assessed by 24-h recalls and a food frequency questionnaire (FFQ). TEE and EI values, EI-to-TEE ratios and EI-TEE values were compared. Results: TEE was 2,220 +/- 601 kcal, while the EI was 1,919 +/- 602 kcal (24-h recall) and 2,119 +/- 670 kcal (FFQ). The proportion of under-reporters was 31 and 40.5%, respectively. Under-reporting was more frequent in subjects with higher percentage of body fat and in females (P < 0.05). Conclusion: under-reporting was more frequent among older persons with higher percentage of body fat in both methods of assessment of food intake. Older persons follow the same profile of under-reporting as younger adults.