Randomized controlled trial of a comprehensive home environment-focused weight-loss program for adults.

The prevalence of overweight and obesity in U.S. adults now exceeds 65% (Flegal, Carroll, Ogden, & Curtin, 2010) with current estimates suggesting that the entire U.S. adult population will reach an unhealthy weight status by 2048 (Wang, Beydoun, Liang, Caballero, & Kumanyika, 2008). Drivers of this trend are multi-faceted, ranging from individual behavioral choices to community land-use planning decisions to global food production practices that promote energy imbalance (e.g., Swinburn et al., 2011). Behavioral weight loss treatment (BWL), the treatment of choice for overweight to moderately obese individuals, includes nutrition and physical activity education and instruction in behavioral strategies to facilitate change, and produces weight losses of approximately 9.0 kg over 6 months of treatment (e.g., Wing, Gorin, & Tate, 2006). While BWL’s modest weight losses and accompanying physical activity and dietary changes produce meaningful health improvements (e.g., Diabetes Prevention Program Research Group, 2002; Look AHEAD Research Group, 2007), participants typically regain 30–50% of their weight loss over the next 3 to 5 years despite ongoing intervention (e.g., Look AHEAD Research Group, 2010). One possible explanation for this weight regain is that BWL focuses primarily on the individual participant, with lesser attention paid to the environmental context in which eating and exercise occurs. While behavioral theory and early weight loss programs emphasized the impact of environmental antecedents and consequences on behavior (e.g., Stuart & Davis, 1972), in current practice, individuals are given limited instruction on how to modify their surroundings to support weight-regulating behaviors. In a standard 6-month program, 1 to 2 sessions are typically dedicated to stimulus control skills (e.g. placing fruits and vegetables in prominent locations), (Wing, Gorin, & Tate, 2006). If weight loss participants are unable to use these skills to alter their personal environments, unhealthy cues and temptations may remain making it extremely difficult to establish and maintain the behavioral changes necessary to produce long-term weight loss (e.g., Bouton, 2000; Lowe, 2003). This individual-level approach to weight management is inconsistent with the growing recognition of the environment’s contribution to the obesity epidemic (e.g., French, Story, & Jeffery, 2001; Swinburn et al., 2011). American adults are described as living in a “toxic environment” that encourages passive overeating and physical inactivity (Wang & Brownell, 2005). Social ecological models of health promotion (Breslow, 1996; Stokols, 2000) identify several levels of environmental influence on diet and physical activity, ranging from familial to global factors. At the most proximal level, there is increasing evidence that the home microenvironment can be obesogenic. Both physical (e.g., type of food available) and social (e.g., support from family) factors in this setting have been associated with weight, dietary habits, and activity patterns (e.g., Campbell, Crawford, Salmon, Carver, Garnett, & Baur, 2007; Gorin, Phelan, Raynor, & Wing, 2011). Demonstrated links between the physical home environment and behavior include relationships between high fat foods available and fat intake (Fulkerson et al., 2008), access to home exercise equipment and activity levels (Gattshall et al., 2008; Jakicic, Wing, Butler, & Jeffery, 1997), and number of televisions and amount of TV viewing (Dennison, Erb, & Jenkins, 2002). With regards to social factors, adults within the same household can serve as powerful behavioral cues and either facilitate or hinder adoption of healthy habits. For example, both weight gain and weight loss appear to spread among spouses (Christakis & Fowler, 2007; Gorin et al., 2008) and correlations have been reported between husbands and wives in caloric intake, dietary restraint, and exercise frequency (e.g., Macken et al., 2000; Markey, Markey, & Birch, 2001). Given that approximately two-thirds of daily calories are consumed in the home and a large percentage of leisure time is spent in this environment (Biing-Hwan, Geuthri, & Frazao, 1999; Robinson & Godbey, 1997), modifying households to promote healthy choices is a logical step in moving toward a broader ecological model of weight management. Weight loss programs that have included home environment modifications such as food provision, provision of exercise equipment, and involving spouses in treatment have produced better overall weight losses for up to 18 months than standard behavioral programs, particularly in women (Black, Gleser, & Kooyers, 1990; Jakicic, Winters, Lang, & Wing, 1999); however these strategies have been largely unsuccessful in producing better maintenance of weight loss. Environmental manipulations to date have typically focused on either a single physical factor in the home (such as provision of food or exercise equipment) or on the social climate of the home (spouse involvement in treatment). This singular focus may not change the overall obesogenic nature of the household, leaving participants vulnerable to environmental influence. Moreover, this singular focus does not address the interaction between physical and social factors within the home (e.g., food provision may be unsuccessful if family members bring tempting foods into the home). Ecological models suggest that interventions will be most effective in changing behavior if they address multiple factors within a given environment, thus to examine the true potential of home environment manipulations in obesity treatment, a more comprehensive intervention targeting several aspects within the household may be needed. The primary aim of this randomized controlled trial was to examine the long-term impact of a comprehensive home-focused behavioral weight control program designed to directly modify both the physical and social home environments of weight loss participants. To our knowledge, this is the first weight loss program to intervene simultaneously on multiple levels of the home environment while also teaching participants core behavioral skills. We hypothesized that by extending the focus of treatment from the individual participant to the participant plus their home environment, the intervention would enhance initial and long-term weight loss outcomes and improve maintenance of weight loss compared to standard behavioral weight loss treatment. Prior research has suggested that women may benefit more from a home-based approach (Wing, Marcus, Epstein, & Jawad, 1991), thus secondary analyses explored gender as a potential treatment moderator. We also examined potential effects on household partners and hypothesized that greater weight loss and behavior changes would be observed in partners who were actively included in the intervention.