THE IMPRECISION OF BODY WEIGHT REGULATION IN RESPONSE TO A LACK OF COMPENSATION TO IMPOSED ENERGETIC CHALLENGES

Abstract

Obesity and associated pathologies of being overweight is now the number one preventable cause of death and is a serious public health threat. Research indicates the cause of obesity is due to a chronic hypercaloric intake, ergo, treatment and prevention should be targeted at eating behaviors. While many believe in the Set Point theory, that is, body weight is tightly regulated and programed to be a specific value, evidence suggests otherwise. Data show that there is poor regulation of body weight (fat) and physiological mechanisms do not precisely correct for energy imbalances. This dissertation examines the precision of body weight regulation and attempts to identify practical strategies to prevent weight gain. First a review of the literature discusses various energetic challenges and examines how precise humans compensate. Furthermore, quantifies the range of energetic error before physiological mechanisms correct for the imbalance. A pilot study was conducted to investigate if a daily 12-hour fast would prevent weight gain and affect sleep behavior. Due to poor adherence, we were unable to draw conclusions about time restricted feeding (TRF). A larger TRF study among adults was conducted to test TRF as a weight management tool and sleep aid. TRF did not cause significant weight loss, but it did significantly improve sleep quality. No research has investigated the feasibility or acceptability of TRF as a lifestyle, so individual interviews were conducted among 21 TRF participants. Experiences with TRF were mixed. The largest positive aspect was an improved sense of control and self-efficacy. The largest negative aspect reported was a hindrance on socializing. Mixed experiences indicate TRF may not be a feasible lifestyle for everyone. Future research should attempt to identify characteristics of individuals who may be more successful at TRF. Finally, a blind cross-over portion reduction study attempted to find the point at which participants compensate for a reduced portion and increase intake of another food. At no point (up to 25% reduction) did participants compensate and increase consumption of dessert. This study was the first to directly measure effects of portion reduction in a within-meal setting.