A Critical Review of Human Psychology and Behavior Research to Examine the Biological and Methodological Plausibility of Obesity Research Findings Candace D. Rutt, Ph.D. Centers for Disease Control and Prevention

The Importance of the Individual How does individual psychology and behavior interact with the environment to affect caloric intake and caloric expenditure?

Increasing Obesity Results about caloric intake over time have been mixed Over the last several decades daily energy expenditure has decreased –Leisure-time activity –Occupational physical activity –Activities of daily living Increase in attractive sedentary activities (James, 1995; McArdle et al., 1997)

Caloric Intake Hunger is not determined by biological mechanisms alone Preferences –Innate –Experience –Cultural (Abbot et al., 1998; Berthoud & Seeley, 2000; Birch & Marlin, 1982; Birch et al., 1980; Birch et al., 1984; Birch et al., 1987; Grundy, 1998; Lipsitt &Behl, 1990; Weingarten, 1983)

Caloric Intake Portion sizes Increased variety Presence of others Availability of food More time in automobiles –Preference for convenience foods –Easy access while driving (Berry et al., 1985; Bureau of the Census, 1976; 2000; Center for Science in Public Interest, 2003; Edelman et al., 1986; Polivy et al., 1979 Porikos et al., 1982; Rolls et al., 1992; Rolls & Hetherington, 1989)

Physical Activity 30 minutes of moderate to vigorous physical activity on most days of the week Community Guide –Enhanced access with informational outreach –Street-scale urban design –Community-scale urban design

Physical Activity and the Environment Characteristics of the environment may have various impacts on different types of physical activities Variations of environmental impact on physical activity and obesity seen in different populations

Walking for Transportation Density (+) Land-use mix (+) Connectivity (+) Sidewalks (+) High walkable neighborhood (+) Car ownership (-) Access to beach (-) (Frank & Engelke, 2001; 2002; Giles-Corti., 2002; Moudon et al., 1997; Ross & Dunning, 1997; Saelens et al., 2003)

Walking for Leisure Density (na) Connectivity (na) Sidewalks (+ na) Land-use (+ and -) Convenient Facilities (+ and na) Sprawl (-) High walkable neighborhood (na) Traffic (- and +) Hills (+) Safety (+ and -) Aesthetics (+) Costal location (+) (Ball et al., 2001; Brownson et al., 2001; de Bourdeaudhuij et al., 2003; Ewing et al., 2003; Hovel et al., 1989; 1992; Humpel et al., 2004;Rutt & Coleman, in press; Saelens et al., 2003) (Ball et al., 2001; Brownson et al., 2001; de Bourdeaudhuij et al., 2003; Ewing et al., 2003; Hovel et al., 1989; 1992; Humpel et al., 2004;Rutt & Coleman, in press; Saelens et al., 2003)

Moderate & Vigorous Physical Activity Density (na) Land-use (na) Connectivity (na) Sidewalks (+ and na) Heavy traffic (+) Access to parks (+) Number of facilities (na) Availability of pay facilities (+) Distance to facilities (+) Slope (na) Hills (+) (Brownson et al., 2001 ; King et al., 2000; Rutt & Coleman, in press; Saelens et al., 2003; Sallis et al., 1990)

Obesity Density (+ and na) Connectivity (na) Land-use mix (- and +) Sprawl (+) Living in high walkable neighborhoods (-) Lack of sidewalks (+) Time spent in car (+) Owning a car (+) (Bell & Popkin, 2003; Ewing et al., 2003; Frank et al., 2004; Giles-Corti et al., 2003; Saelens et al., 2003; Reddy et al., 1997; Rutt & Coleman, in press)

Reasons for Inconsistencies No standardized way to measure many environmental variables Poor agreement between subjective and objective measures of the environment High correlations between urban form variables Individual level characteristics (Kirtland et al., 2003; Sallis et al., 1990; Troped et al., 2001)

Individual Level Differences Variations in environmental correlates seen across –Gender –Ethnicity –Income (de Bourdeadhuij, 2003; Flynn & Fitzgibbon, 1998; Flegal et al., 1998; Humpel et al,. 2004; 2004; Voorhees & Young, 2003; )

Individual Level Differences 46% of adults in the U.S. believe that their neighborhood is unsafe. This rate was double in minority households Residents of poor neighborhoods walk more despite the fact that they report more fear of being victimized (Princeton Survey Research Associates, 1994; Ross, 2000)

Individual Level Differences For those with low incomes, the most important environmental variable associated with walking was enjoyable scenery For those with higher incomes sidewalks were the most important variable (Brownson et al., 2001)

Reasons for Inconsistencies Most studies include some basic demographic variables Usually do not measure psychological or social variables that could affect behavior Self-selection into neighborhoods –Individual level characteristics associated with certain types of neighborhoods

Reasons for Inconsistencies Households choose residential locations partly based on desired travel behavior Several researchers have found clusters of lifestyle and demographic variables that were linked to transportation choices Attitudinal and demographic variables have been found to be more strongly associated with travel than built environment characteristics (Boarnet & Sarmiento, 1998; Boarnet & Greenwald, 2000; Cervero & Duncan, 2003; Giles-Corti & Donovan, 2002; Kitamura et al.,1997; Hanson, 1982; Rutt & Coleman, in press; Salomon & Ben Akiva, 1983; Zimmerman, 1982)

Mode choice Only one study which has examined travel behavior before and after a move –Over half of the families moved to similar neighborhoods –Decreases in walking and biking trips were seen in those that relocated from a low auto-dependent neighborhood to a medium auto-dependent neighborhood (Krizek, 2000) (Krizek, 2000)

Mode choice Travel time is the most important predictor of mode choice Out-of-vehicle travel time (walking, biking) is considered more costly than in-vehicle travel time However other components of the trips (aesthetics, safety, etc.) affect the price or utility of the trip (Handy et al., 2002)

Variance Explained Of the six classes of determinants (demographic, psychological, behavioral, social, environment), individual level variables had the strongest and most consistent associations with physical activity Studies usually explain only 30% of the variance in physical activity or travel behavior (Crane et al., 1999; Baranowski, 1998; Handy et al., 1996)

Environment and PA An environment that encourages physical activity is necessary but insufficient to increase physical activity We may need better measures of the environment (Trost et al., 1996)

Paradigm Shift Cannot examine how the environment influences physical activity, eating behavior, or obesity without examining the individual Researchers need to start thinking about interactions between variables as well as their independent effects –Ecological Models –Mediators –Moderators (Barron & Kenny, 1986; McLeroy, Bibeau, Steckler, & Glantz, 1988; Sallis & Owen, 1996; Stokols, 1996) (Barron & Kenny, 1986; McLeroy, Bibeau, Steckler, & Glantz, 1988; Sallis & Owen, 1996; Stokols, 1996)

Conclusions Individual level variables should not be simply viewed as “covariates” to be controlled for rather they should be examined as important predictors of travel behavior and physical activity If individual level variables are not included in the emerging literature, incorrect conclusions may be drawn about the relationship between the environment and obesity