Date of Award
Doctor of Philosophy in Biological and Environmental Sciences
Sustainable Agriculture and Food Systems (SAFS)
Nutrition and Food Sciences
Obesity is a serious public health problem. There is a need for scalable weight loss interventions that can help people lose weight and decrease their risk of obesity related chronic disease development. Self-monitoring is a key component of successful weight loss. The Eat Less, Move More (ELMM) device is wrist-worn, and is capable of counting bites by detection of a wrist-roll motion that is specific to eating. The device can also measure seconds between bites, as a proxy to eating rate (ER) measurement, as well as the number of steps taken by the user. The aim of this body of research was to explore the effects of the ELMM device within a weight loss intervention focused on decreasing the size and number of bites, reducing ER, and increasing physical activity, as well as increasing awareness of physiological cues to eating. The first chapter focuses on the examination of the ELMM device-assessed proxy to ER, seconds between bites, with self-reported eating rate (SRER). The average number of seconds between bites as measured by the ELMM device is referred to in this body of work as the bite count interval (BCI). Data from the first three days of participants’ use of the ELMM to track bites and BCI were examined, and results showed a significant difference in BCI as measured by the ELMM among SRER categories. These findings suggest that the ELMM is capable of measuring BCI in free-living eating situations, an important first step in establishing the validity of this device in its ability to reflect free-living eating rate. The second chapter explores the effects of a workbook-based weight loss intervention on body weight change (primary outcome), and energy intake (EI), ER, and energy expenditure (secondary outcomes), with (workbook plus device or WD group) and without (workbook only or WO group) the addition of the self-monitoring ELMM device. There was a strong main effect of time on weight change, but there was no significant difference between groups in body weight change. No significant differences were seen between groups in ER, EI or energy expenditure. At the end of the intervention, participants were dichotomized into a weight loss group (WL) or a weight stable/gainers group (WSG). A strong overall main effect of time, and a significant time by WL/WSG group interaction was seen in scores from the validated weight-related eating questionnaire (WREQ). Post hoc univariate analyses showed a significant effect of time on restraint scores, and a significant time by group interaction on susceptibility to external cues scores. These findings suggest that participants who were most likely to respond to external eating cues, regardless of internal hunger and satiety signals, had more success with this intervention. Chapter three examines changes in resting metabolic rate (RMR) as measured by indirect calorimetry within the weight loss intervention. Secondary outcomes observed changes in substrate oxidation as measured by respiratory exchange ratio (RER), body fat percent, and energy expenditure as estimated by the 7-day Physical Activity Recall (PAR-EE). Exploratory outcomes included the investigation of eating behaviors as measured by the validated Intuitive Eating Scale-2 (IES-2) as they relate to weight loss as a result of the intervention. Prepost changes in RMR, RER, body fat percent and PAR-EE were not statistically significant. A significant, moderate negative correlation was found between week 8 PAR-EE and week 8 RER. A significant, moderate negative association was also found between week 8 in body fat percent change and RER change. Exploratory outcome results showed a significant time by WL vs. WSG group effect of IES-2 subscale scores, and follow-up univariate analyses showed a significant time by WL vs. WSG effect of the Eating for Physical Reasons rather than Emotional Reasons (EPR) subscale. These results demonstrate that even small changes in body fat percent and energy expenditure from physical activity were associated with beneficial effects on resting fat oxidation. In summary, results from this body of work provide an important first step in examining the validity of the ELMM device in assessing a proxy to free-living eating rate. Moreover, these findings show that an intervention focused on decreasing bites, reducing eating rate, and increasing physical activity is effective for weight loss, and that participants who are more susceptible to external eating cues may be more responsive to this type of intervention. Additionally, participants with increased physical activity after an 8-week weight loss intervention tended to have higher fasting fat oxidation, suggesting that even with minor changes, increased energy expended in physical activity may be associated with greater fat oxidation, which may favor weight loss maintenance. Finally, participants who improved in eating behavior related to the IES-2 Eating for Physical Reasons rather than Emotional Reasons (EPR) subscale, were more successful in weight loss within this type of intervention. This work provides fresh insight into the existing eating rate research, and adds new information to the behavioral weight loss intervention and eating behaviors literature.
Beatty, Jacqueline Ann, "Exploring the Role of a Novel Device in Weight Loss Outcomes and Behaviors" (2018). Open Access Dissertations. Paper 729.