Date of Award

Spring 3-23-2015

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Nutrition

First Advisor

Megan McCrory

Second Advisor

Dan Benardot

Third Advisor

Anita Nucci

Abstract

Background: The relationship between eating frequency (EF) and adiposity is surrounded by controversy. Numerous cross-sectional studies have been performed on the subject, yet the results are mixed. While some of these studies show an inverse relationship between EF and adiposity, this is likely due to underreporting of EF and total energy intake when diets are self-reported. In studies where underreporting was taken into account, EF is positively associated with both energy intake and adiposity. Intervention trials have failed to show a significant effect of EF on energy intake or weight change, but only a small number exist.

Objective: In this study, we examined associations among EF, energy intake, and adiposity in free living adults consuming self-selected diets. In conducting this analysis, two common methodological problems in this research area were addressed: 1) the lack of consideration of energy balance fluctuations throughout the day, and 2) a tendency not to account for implausible reporting of energy intake. We hypothesized that individuals with higher EF would have higher BMI, percentage body fat, and energy intake. Additionally individuals with greater fluctuations in energy balance will have higher BMI, percentage body fat, and EF.

Methods: We performed a secondary analysis of data collected as part of a previous study in our laboratory on diet and energy regulation (unpublished). One hundred and twenty-six participants were enrolled (62.4 % female, and 75.2% Caucasian), and one participant dropped the study due to pregnancy. Mean ±SD age, BMI, and percentage body fat of the remaining 125 participants were 29.8 ±12.2 years, 24.5±3.9 kg/m2, and 27.8±9.8% respectively. We analyzed one day of dietary intake collected using a multiple pass 24 hour recall. Energy intake was calculated by NDS (Nutrition Data System for Research, version 2011 (n=36) and version 2010 (n=89)). An eating occasion was defined as any occurrence of energy intake > 0 kcal separated by at least 1 hour. EF was defined as the number of eating occasions per day. A specifically designed spreadsheet that generates within-day energy balance was used to produce estimates of hourly energy balance. We also used total energy expenditure measured by doubly labeled water and the Huang et al. (2005)1 method to identify implausible reporters (cutoff for plausibility was reported energy intake (REI) within ±16.8% of TEE) and conducted Pearson’s correlations and regression analysis in both the total sample and a subsample in which implausible energy intake reporters were excluded from analysis.

Results: We identified 59.2% of the sample as implausible reporters (n=74; 47 under-reported and 27 over-reported). Mean ±SD EF and energy intake were 4.7±1.5 and 2356±964 kcal in the total sample and 4.8±1.6 and 2371±689 kcal in the plausible sample. In the total sample EF was positively correlated to energy intake among women (r=0.244, p=0.032). No other significant relationships were observed between EF and either energy intake, BMI, or percentage body fat, in the total or plausible sample. In the total sample, maximum energy deficit > 400 kcal in a 24 hours period was significantly and positively correlated with percentage body fat (r=0.211,p=0.019) and negatively correlated with EF (r=-0.243, p=0.007) when controlling for sex and age. Separating the sample by sex we observed significant positive correlation between percentage body fat and maximum energy deficit in men (r=0.382, p=0.009) but not in women. No significant relationships between fluctuations in energy balance and percentage body fat were observed in the plausible sample.

Conclusion: No evidence was found to suggest a relationship between EF and adiposity. The significant positive relationships observed between maximum energy deficit and adiposity in the total sample are consistent with previous findings. The number of implausible reporters identified in our analysis supports that over and under-reporting is a major issue associated with self-reporting of dietary intake.

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