Postprint version. Published in Journal of the American Dietetic Association, Volume 106, Issue 11, November 9, 2006, pages 1851-1855.
NOTE: At the time of publication, the author Alison Ventura was not yet affiliated with Cal Poly.
The definitive version is available at https://doi.org/10.1016/j.jada.2006.08.003.
We explored the relationships among girls’ weight status, dairy servings, and total energy intake. The hypothesis that consuming dairy could reduce risk for overweight was evaluated by comparing energy intake and weight status of girls who met or consumed less than the recommended three servings of dairy per day. Participants included 172 11-year-old non-Hispanic white girls, assessed cross-sectionally. Intakes of dairy, calcium, and energy were measured using three 24-hour recalls. Body mass index and body fat measures from dual-energy x-ray absorptiometry were obtained. Because preliminary analyses suggested systematic underreporting of energy intake, the relationships among dairy servings and measures of weight status were examined for the total sample and for subsamples of under-, plausible, and overreporters. Data for the total sample provided support for the hypothesized relationship among weight status, dairy servings, and energy intake. Thirty-nine percent of girls reported consuming the recommended ≥3 servings of dairy per day; these girls also reported higher energy intake but had lower body mass index z scores and body fat than the girls who consumed fewer than three dairy servings each day. Among plausible reporters, no relationship between dairy intake and weight status was noted. This discrepancy may be attributable to a high percentage (45%) of overweight underreporters in the total sample. Our findings reveal that reporting bias, resulting from the presence of a substantial proportion of underreporters of higher weight status, can contribute to obtaining spurious associations between dairy intake and weight status. These findings underscore the need for randomly controlled trials to assess the role of dairy in weight management.
The prevalence of pediatric obesity has been rising for more than 20 years (1). There is evidence that increased intake of dairy foods and calcium may play a significant role in maintaining a healthful weight and moderating body fat (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 and 15). However, results across studies have been inconsistent (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27 and 28), and this may be attributable to major challenges in using self-reported dietary intake data. Self-reported intakes tend to be subject to underreporting bias and the underreporting of energy intake tends to be positively related to weight status. Underreporters also tend to weigh more (29 and 30). Doubly labeled water techniques assessing energy expenditure suggest underreporting results in a 10% to 50% underestimation of actual energy intake and is a significant problem in older children (31). Doubly labeled water techniques are expensive and not feasible for large samples; thus, several methods have been developed that use estimated energy requirements to assess reporting bias (29 and 32). Therefore, in this study the method suggested by Huang and colleagues (29) was used to classify children as under-, plausible, or overreporters. The objective of this study was to assess the relationship among girls’ weight status, dairy servings, and total energy intake. The hypothesis that consuming dairy could reduce risk for overweight was evaluated by comparing energy intake and weight status of girls who met or consumed less than the recommended three servings of dairy per day. To explore the effect of reporting bias on this relationship, the hypothesis was evaluated using the total sample, and subgroups of girls identified as plausible, under-, or overreporters.