The Effects of Overfeeding on Spontaneous Physical Activity in Obesity Prone and Obesity Resistant Humans

Abstract

Despite living in an environment that promotes weight gain in many individuals, some individuals maintain a thin phenotype while self-reporting expending little or no effort to control their weight. When compared with obesity prone (OP) individuals, we wondered if obesity resistant (OR) individuals would have higher levels of spontaneous physical activity (SPA) or respond to short-term overfeeding by increasing their level of SPA in a manner that could potentially limit future weight gain. SPA was measured in 55 subjects (23 OP and 32 OR) using a novel physical activity monitoring system (PAMS) that measured body position and movement while subjects were awake for 6 days, either in a controlled eucaloric condition or during 3 days of overfeeding (1.4× basal energy) and for the subsequent 3 days (ad libitum recovery period). Pedometers were also used before and during use of the PAMS to provide an independent measure of SPA. SPA was quantified by the PAMS as fraction of recording time spent lying, sitting, or in an upright posture. Accelerometry, measured while subjects were in an upright posture, was used to categorize time spent in different levels of movement (standing, walking slowly, quickly, etc.). There were no differences in SPA between groups when examined across all study periods (P > 0.05). However, 3 days following overfeeding, OP subjects significantly decreased the amount of time they spent walking (−2.0% of time, P = 0.03), whereas OR subjects maintained their walking (+0.2%, P > 0.05). The principle findings of this study are that increased levels of SPA either during eucaloric feeding or following short term overfeeding likely do not significantly contribute to obesity resistance although a decrease in SPA following overfeeding may contribute to future weight gain in individuals prone to obesity.

Effects of weight gain induced by controlled overfeeding on physical activity

“…*Change values that are significantly different from 0 at P Յ 0.05. libitum feeding, during which time energy expenditure and activity were free to vary (1). Similar results have been found in other studies in individuals prone to obesity (27). These results suggest that participants may actually decrease AEE following short-term overfeeding, as was found with the nonsignificant reduction in VM during the first 2 wk in our study.…”

Propensity to Obesity Impacts the Neuronal Response to Energy Imbalance

“…As we have previously described, subjects were recruited to have a propensity to be resistant to weight gain and obesity (OR) or to be prone to weight gain and obesity (OP) (Schmidt et al, 2012, 2013; Smucny et al, 2012; Cornier et al, 2013; Thomas et al, 2013, 2014). Subjects were 25–40 years of age and were free of significant medical and psychiatric disease, including eating disorders as assessed by screening medical history, physical examination, biochemical testing, and questionnaires [eating attitudes test (Garner et al, 1982) and the Center for Epidemiologic Studies Depression Scale (Radloff, 1977)].…”

Brain structure predicts risk for obesity

“…Subjects were healthy men and women without eating disorders aged 25–40 empirically classified as either obesity resistant (OR) or obesity prone (OP) as previously defined (Schmidt et al, 2012). Specifically, OR subjects responded to advertisements for “naturally thin people”.…”

“…In the present study, we used whole brain voxel-based morphometry (VBM) to examine structural brain differences between Obese Prone (OP) and Obese Resistant (OR) individuals. Subjects were empirically classified as OR or OP based on personal and family weight history, as defined previously (Schmidt, Harmon, Sharp, Kealey, & Bessesen, 2012). Studying OP, as opposed to already obese or reduced-obese individuals, reveals structural brain differences that may precede weight gain and obesity and therefore could be a causative mechanism and/or be used as a predictor of obesity risk.…”