Children differ greatly in their ability to self-regulate food intake for reasons that are poorly... more Children differ greatly in their ability to self-regulate food intake for reasons that are poorly understood. This laboratory-based twin study tested the genetic and environmental contributions to self-regulatory eating and body fat in early childhood. A total of 69 4-7 year-old same-sex twin pairs, including 40 monozygotic and 29 dizygotic pairs, were studied. Self-regulatory eating was operationalized as the percentage compensation index (COMPX%), assessed by a 'preload' challenge in which lunch intake was measured following a low- (3 kcal) or high-calorie (159 kcal) drink. Body fat indexes also were measured. The familial association for COMPX% was estimated by an intraclass correlation, and biometric analyses estimated heritability. Children ate more at lunch following the low- compared with high-energy preload (P<0.001), although variability in COMPX% was considerable. Compensation was significantly poorer among African American and Hispanic compared with European Am...
This study evaluated the influence of child and family functioning on child sleep behaviors in lo... more This study evaluated the influence of child and family functioning on child sleep behaviors in low-income minority families who are at risk for obesity. A cross-sectional study was utilized to measure child and family functioning from 2013 to 2014. Participants were recruited from Head Start classrooms while data were collected during home visits. A convenience sample of 72 low-income Hispanic (65%) and African American (32%) families of preschool-aged children were recruited for this study. We assessed the association of child and family functioning with child sleep behaviors using a multivariate multiple linear regression model. Bootstrap mediation analyses examined the effects of family chaos between child functioning and child sleep problems. Poorer child emotional and behavioral functioning related to total sleep behavior problems. Chaos associated with bedtime resistance significantly mediated the relationship between Behavioral and Emotional Screening System (BESS) and Bedtim...
Journal of the American Dietetic Association, 2008
This study was conducted to describe mealtimes and explore routines, policies, and training in ch... more This study was conducted to describe mealtimes and explore routines, policies, and training in child-care centers. Following an intensive review of mealtimes, staff and director questionnaires were created. Using a stratified random sampling protocol and following the Tailored Design Method, directors and staff from licensed child-care centers from California, Colorado, Idaho, and Nevada were surveyed. Center and staff characteristics were compared among the four states and three census areas using analysis of variance and 2 analyses, as appropriate. To adjust for multiple comparisons, a stringent P value of Ͻ0.001 was used for post hoc comparisons. Responses were received from 568 centers (representing 1,190 staff and 464 directors). Mealtimes generally occurred in the classroom, where an adult sat at the table with the children, served some food, poured the drinks, and ate some of the center-provided food. Less than half of centers reported using "family-style" service, although this style allows children the opportunity to self-serve food. Staff received substantially less training on feeding children (42%) than on nutrition (68%) and child development (95%). These findings bring focus to the need to educate child-care staff and directors about the impact of mealtime environments on child health and development. J Am Diet Assoc. 2008;108:340-346.
Within the field of nutrition education, social marketing has become a promising framework to sys... more Within the field of nutrition education, social marketing has become a promising framework to systematically approach problems related to nutrition behavior. In 1997, the Colorado Nutrition Network began developing a social marketing campaign to promote healthful food choices among low-income Coloradans. A multifaceted formative evaluation plan that included focus groups, campaign concept pretesting, and a food fiequency questionnaire was used to segment and scrutinize the target audience. The resulting pilot program was a blend of educational and marketing strategies targeting preschoolers that was implemented in Head Start classrooms. The 12-week intervention contained a narrow, behavior-based "try new foods" message, multiple nutrition education activities, and repeated opportunities to taste 13 novel foods. Key strategies used and findings from the formative evaluation process are presented here in an effort to provide insight for nutrition educators interested in developing similar interventions.
ABSTRACT The Child and Adult Care Food Program (CACFP) plays a critical role by providing food to... more ABSTRACT The Child and Adult Care Food Program (CACFP) plays a critical role by providing food to children from low-income families while they are enrolled in licensed childcare or attending approved after-school programs. There is little documentation about ...
Children differ greatly in their ability to self-regulate food intake for reasons that are poorly... more Children differ greatly in their ability to self-regulate food intake for reasons that are poorly understood. This laboratory-based twin study tested the genetic and environmental contributions to self-regulatory eating and body fat in early childhood. A total of 69 4-7 year-old same-sex twin pairs, including 40 monozygotic and 29 dizygotic pairs, were studied. Self-regulatory eating was operationalized as the percentage compensation index (COMPX%), assessed by a 'preload' challenge in which lunch intake was measured following a low- (3 kcal) or high-calorie (159 kcal) drink. Body fat indexes also were measured. The familial association for COMPX% was estimated by an intraclass correlation, and biometric analyses estimated heritability. Children ate more at lunch following the low- compared with high-energy preload (P<0.001), although variability in COMPX% was considerable. Compensation was significantly poorer among African American and Hispanic compared with European Am...
A chronic mismatch of caregiver responsiveness to infant-feeding cues, such as feeding when the i... more A chronic mismatch of caregiver responsiveness to infant-feeding cues, such as feeding when the infant is not hungry, is hypothesized to have a role in the development of overweight by impairing an infant's response to internal states of hunger and satiation. Although this concept of mismatch or discordance has long been acknowledged in scholarly writings, a systematic assessment of the evidence supporting the role of discordant responsiveness during infant feeding in the early origins of overweight is lacking. This review was undertaken to assess evidence for this hypothesized relationship between discordant responsiveness in feeding and overweight in infancy and toddlerhood, framed within the larger social-environmental context of the infant-caregiver dyad. A systematic method was used to extract articles from three databases of the medical, psychology and nursing fields. The quality of evidence collected was assessed using Oxford University Centre for Evidence Based Medicine&...
Preschool-aged children consistently self-regulate energy intake by adjusting food intake to refl... more Preschool-aged children consistently self-regulate energy intake by adjusting food intake to reflect the energy density of the diet. However, only select adults demonstrate self-regulation skills related to energy density cues. The objective was to examine the developmental characteristics of non-Hispanic white and Hispanic children's self-regulation of energy intake and to determine whether individual differences in the precision of food intake regulation were related to the children's anthropometric measures. Three hundred forty-two 5-12-y-old children were recruited from 2 schools, one school that enrolled predominantly non-Hispanic white children (n = 148) and another school in a Hispanic neighborhood (n = 194). The children ate 2-part meals, which consisted of a preload and a main meal. The preloads were fruit-flavored drinks that were either high (625 kJ) or low (12.5 kJ) in energy density. The children's food intake at the meal was measured and energy intake was e...
Dietary studies are often conducted as longitudinal intervention or crossover trials using multip... more Dietary studies are often conducted as longitudinal intervention or crossover trials using multiple days of measurement on each subject during each of several measurement periods, and determining the required numbers of days and subjects is important in designing these studies. Linear mixed statistical models were used to derive equations for precision, statistical power and sample size (number of days and number of subjects) and to obtain estimates of between-subject, period-to-period, and day-to-day variation needed to apply the equations. Two cohorts of an on-going exercise intervention study, and a crossover study of Olestra, each with 14 d of measurement/subject per period, were used to obtain estimates of variability for energy and macronutrient intake. Numerical examples illustrate how the equations for calculating the number of days or number of subjects are applied in typical situations, and sample SAS code is given. It was found that between-subject, period-to-period, and day-to-day variation all contributed significantly to the variation in energy and macronutrient intake. The ratio of period-to-period and day-to-day standard deviations controls the trade-off between the number of days and the number of subjects, and this remained relatively stable across studies and energy and macronutrient intake variables. The greatest gains in precision were seen over the first few measurement days. Greater precision and fewer required days were noted in the study (Olestra) that exerted greater control over the subjects and diets during the feeding protocol.
To examine the effects of ad libitum diets with three distinct levels of fat intake for the preve... more To examine the effects of ad libitum diets with three distinct levels of fat intake for the prevention of weight gain in sedentary, normal-weight and overweight men and women. Methods and Procedures: Three hundred and five participants were randomized to one of three diets. The diets targeted <25% of energy from fat (low fat (LF)), between 28 and 32% of energy from fat (moderate fat (MF)), or >35% of energy from fat (high fat (HF)). Participants consumed two meals per day on weekdays and one meal per day on weekends in a university cafeteria over a 12-week period. Energy and nutrient content of cafeteria foods were measured by digital photography. All meals and snacks consumed outside the cafeteria were measured by dietary recall. All analysis of energy and nutrient content was completed using Nutrition Data System for Research (NDS-R) version 2005. Results: Two hundred and sixty participants completed the study. LF gained 0.1 ± 3.1 kg, MF gained 0.8 ± 2.5 kg, and HF gained 1.0 ± 2.2 kg and there was no gender or age effect. Longitudinal mixed modeling indicated a significant difference among the groups in weight over time (P = 0.0366). When adjusting for total energy intake, which was a significant predictor of weight over time, the global effect for the group was eliminated. Thus, increasing weight was a function of increasing energy but not increasing percentage of fat intake. Discussion: Energy intake, but not percentage of energy from fat, appears responsible for the observed weight gain. LF diets may contribute to weight maintenance and HF diets may promote weight gain due to the influence of fat intake on total energy intake.
Children's eating behaviors are driven by nutrient needs for growth and health, their development... more Children's eating behaviors are driven by nutrient needs for growth and health, their developmental stage, and by physical and social aspects of the feeding environment. Engendering healthful eating styles requires recognition of children's needs and abilities and a positive, structured environment in which learning and self-regulation are encouraged.
Research conducted in the 1930s showed that, given nutritious choices, children can select an ade... more Research conducted in the 1930s showed that, given nutritious choices, children can select an adequate diet without adult supervision. Paradoxically, children grew well and were healthy despite patterns of intake at individual meals that were unpredictable and highly variable. To investigate in more detail the energy intake of young children, we measured 24-hour food intake for 15 children, from two to five years of age, on six days. For each of the six days of the study, coefficients of variation were calculated for each child for each of the six meals and snacks (breakfast, lunch, dinner, and morning, afternoon, and evening snacks) and for total daily energy intake. The children&#39;s intake at individual meals was highly variable, but total daily energy intake was relatively constant for each child. The mean coefficient of variation for each child&#39;s energy intake at individual meals was 33.6 percent; in contrast, the mean coefficient of variation for each child&#39;s total daily energy intake was 10.4 percent. In most cases, high energy intake at one meal was followed by low energy intake at the next meal, or vice versa. Although children&#39;s food consumption is highly variable from meal to meal, daily energy intake is relatively constant, because children adjust their energy intake at successive meals.
Journal of the American Dietetic Association, 2002
... Debra Sullivan, PhD, RD, Department of Dietetics &amp; Nutrition, University of Kansas ..... more ... Debra Sullivan, PhD, RD, Department of Dietetics &amp; Nutrition, University of Kansas ... Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence. ... was associate professor, Human Performance Laboratory, University of Nebraska-Kearney, USA. ,; KATE A ...
Background-Early growth monitoring may not identify infants at-risk for later growth faltering be... more Background-Early growth monitoring may not identify infants at-risk for later growth faltering because it is difficult for the provider to recognize how large of a negative shift might be problematic.
Background: Certain individuals appear to be resistant to weight gain in an obesigenic environmen... more Background: Certain individuals appear to be resistant to weight gain in an obesigenic environment, yet the mechanisms for this adaptation are unclear. These individuals may sense positive energy balance more appropriately than those individuals prone to weight gain.
Nearly all Americans (97%) report eating candy at least once per year, yet, on a given fay, only ... more Nearly all Americans (97%) report eating candy at least once per year, yet, on a given fay, only approximately one-fourth of the US population aged ≥2 y consumes candy. Among all Americans, candy contributes a relatively small proportion of calories, added sugars, and saturated fat to the total diet, and recent research suggests that current levels of candy consumption are not associated with risk of weight gain and cardiovascular disease in children and adults. Providing guidance for the consumption of candy in moderation requires and understanding of various behavioral health-related factors that influence candy consumption. A roundtable of behavioral nutrition experts, researchers, and nutrition educators met to discuss recent data on intakes of candy, health outcomes associated with usual candy intake, and the impact of behavioral strategies, including restriction, education, and environmental awareness, on modifying eating behaviors to achieve moderate intakes of candy. Restricting access to palatable foods, whether self-imposed or by parental control, may have potentially negative consequences. Techniques and insight into how to adopt "moderation" in candy consumption, from effective parental practices to environmental strategies that facilitate behavior change without a high degree of effort, were identifies as important next steps towards sustainable dietary guidance related to the role of candy and other treats in a health lifestyle.
Children differ greatly in their ability to self-regulate food intake for reasons that are poorly... more Children differ greatly in their ability to self-regulate food intake for reasons that are poorly understood. This laboratory-based twin study tested the genetic and environmental contributions to self-regulatory eating and body fat in early childhood. A total of 69 4-7 year-old same-sex twin pairs, including 40 monozygotic and 29 dizygotic pairs, were studied. Self-regulatory eating was operationalized as the percentage compensation index (COMPX%), assessed by a 'preload' challenge in which lunch intake was measured following a low- (3 kcal) or high-calorie (159 kcal) drink. Body fat indexes also were measured. The familial association for COMPX% was estimated by an intraclass correlation, and biometric analyses estimated heritability. Children ate more at lunch following the low- compared with high-energy preload (P<0.001), although variability in COMPX% was considerable. Compensation was significantly poorer among African American and Hispanic compared with European Am...
This study evaluated the influence of child and family functioning on child sleep behaviors in lo... more This study evaluated the influence of child and family functioning on child sleep behaviors in low-income minority families who are at risk for obesity. A cross-sectional study was utilized to measure child and family functioning from 2013 to 2014. Participants were recruited from Head Start classrooms while data were collected during home visits. A convenience sample of 72 low-income Hispanic (65%) and African American (32%) families of preschool-aged children were recruited for this study. We assessed the association of child and family functioning with child sleep behaviors using a multivariate multiple linear regression model. Bootstrap mediation analyses examined the effects of family chaos between child functioning and child sleep problems. Poorer child emotional and behavioral functioning related to total sleep behavior problems. Chaos associated with bedtime resistance significantly mediated the relationship between Behavioral and Emotional Screening System (BESS) and Bedtim...
Journal of the American Dietetic Association, 2008
This study was conducted to describe mealtimes and explore routines, policies, and training in ch... more This study was conducted to describe mealtimes and explore routines, policies, and training in child-care centers. Following an intensive review of mealtimes, staff and director questionnaires were created. Using a stratified random sampling protocol and following the Tailored Design Method, directors and staff from licensed child-care centers from California, Colorado, Idaho, and Nevada were surveyed. Center and staff characteristics were compared among the four states and three census areas using analysis of variance and 2 analyses, as appropriate. To adjust for multiple comparisons, a stringent P value of Ͻ0.001 was used for post hoc comparisons. Responses were received from 568 centers (representing 1,190 staff and 464 directors). Mealtimes generally occurred in the classroom, where an adult sat at the table with the children, served some food, poured the drinks, and ate some of the center-provided food. Less than half of centers reported using "family-style" service, although this style allows children the opportunity to self-serve food. Staff received substantially less training on feeding children (42%) than on nutrition (68%) and child development (95%). These findings bring focus to the need to educate child-care staff and directors about the impact of mealtime environments on child health and development. J Am Diet Assoc. 2008;108:340-346.
Within the field of nutrition education, social marketing has become a promising framework to sys... more Within the field of nutrition education, social marketing has become a promising framework to systematically approach problems related to nutrition behavior. In 1997, the Colorado Nutrition Network began developing a social marketing campaign to promote healthful food choices among low-income Coloradans. A multifaceted formative evaluation plan that included focus groups, campaign concept pretesting, and a food fiequency questionnaire was used to segment and scrutinize the target audience. The resulting pilot program was a blend of educational and marketing strategies targeting preschoolers that was implemented in Head Start classrooms. The 12-week intervention contained a narrow, behavior-based "try new foods" message, multiple nutrition education activities, and repeated opportunities to taste 13 novel foods. Key strategies used and findings from the formative evaluation process are presented here in an effort to provide insight for nutrition educators interested in developing similar interventions.
ABSTRACT The Child and Adult Care Food Program (CACFP) plays a critical role by providing food to... more ABSTRACT The Child and Adult Care Food Program (CACFP) plays a critical role by providing food to children from low-income families while they are enrolled in licensed childcare or attending approved after-school programs. There is little documentation about ...
Children differ greatly in their ability to self-regulate food intake for reasons that are poorly... more Children differ greatly in their ability to self-regulate food intake for reasons that are poorly understood. This laboratory-based twin study tested the genetic and environmental contributions to self-regulatory eating and body fat in early childhood. A total of 69 4-7 year-old same-sex twin pairs, including 40 monozygotic and 29 dizygotic pairs, were studied. Self-regulatory eating was operationalized as the percentage compensation index (COMPX%), assessed by a 'preload' challenge in which lunch intake was measured following a low- (3 kcal) or high-calorie (159 kcal) drink. Body fat indexes also were measured. The familial association for COMPX% was estimated by an intraclass correlation, and biometric analyses estimated heritability. Children ate more at lunch following the low- compared with high-energy preload (P<0.001), although variability in COMPX% was considerable. Compensation was significantly poorer among African American and Hispanic compared with European Am...
A chronic mismatch of caregiver responsiveness to infant-feeding cues, such as feeding when the i... more A chronic mismatch of caregiver responsiveness to infant-feeding cues, such as feeding when the infant is not hungry, is hypothesized to have a role in the development of overweight by impairing an infant's response to internal states of hunger and satiation. Although this concept of mismatch or discordance has long been acknowledged in scholarly writings, a systematic assessment of the evidence supporting the role of discordant responsiveness during infant feeding in the early origins of overweight is lacking. This review was undertaken to assess evidence for this hypothesized relationship between discordant responsiveness in feeding and overweight in infancy and toddlerhood, framed within the larger social-environmental context of the infant-caregiver dyad. A systematic method was used to extract articles from three databases of the medical, psychology and nursing fields. The quality of evidence collected was assessed using Oxford University Centre for Evidence Based Medicine&...
Preschool-aged children consistently self-regulate energy intake by adjusting food intake to refl... more Preschool-aged children consistently self-regulate energy intake by adjusting food intake to reflect the energy density of the diet. However, only select adults demonstrate self-regulation skills related to energy density cues. The objective was to examine the developmental characteristics of non-Hispanic white and Hispanic children's self-regulation of energy intake and to determine whether individual differences in the precision of food intake regulation were related to the children's anthropometric measures. Three hundred forty-two 5-12-y-old children were recruited from 2 schools, one school that enrolled predominantly non-Hispanic white children (n = 148) and another school in a Hispanic neighborhood (n = 194). The children ate 2-part meals, which consisted of a preload and a main meal. The preloads were fruit-flavored drinks that were either high (625 kJ) or low (12.5 kJ) in energy density. The children's food intake at the meal was measured and energy intake was e...
Dietary studies are often conducted as longitudinal intervention or crossover trials using multip... more Dietary studies are often conducted as longitudinal intervention or crossover trials using multiple days of measurement on each subject during each of several measurement periods, and determining the required numbers of days and subjects is important in designing these studies. Linear mixed statistical models were used to derive equations for precision, statistical power and sample size (number of days and number of subjects) and to obtain estimates of between-subject, period-to-period, and day-to-day variation needed to apply the equations. Two cohorts of an on-going exercise intervention study, and a crossover study of Olestra, each with 14 d of measurement/subject per period, were used to obtain estimates of variability for energy and macronutrient intake. Numerical examples illustrate how the equations for calculating the number of days or number of subjects are applied in typical situations, and sample SAS code is given. It was found that between-subject, period-to-period, and day-to-day variation all contributed significantly to the variation in energy and macronutrient intake. The ratio of period-to-period and day-to-day standard deviations controls the trade-off between the number of days and the number of subjects, and this remained relatively stable across studies and energy and macronutrient intake variables. The greatest gains in precision were seen over the first few measurement days. Greater precision and fewer required days were noted in the study (Olestra) that exerted greater control over the subjects and diets during the feeding protocol.
To examine the effects of ad libitum diets with three distinct levels of fat intake for the preve... more To examine the effects of ad libitum diets with three distinct levels of fat intake for the prevention of weight gain in sedentary, normal-weight and overweight men and women. Methods and Procedures: Three hundred and five participants were randomized to one of three diets. The diets targeted <25% of energy from fat (low fat (LF)), between 28 and 32% of energy from fat (moderate fat (MF)), or >35% of energy from fat (high fat (HF)). Participants consumed two meals per day on weekdays and one meal per day on weekends in a university cafeteria over a 12-week period. Energy and nutrient content of cafeteria foods were measured by digital photography. All meals and snacks consumed outside the cafeteria were measured by dietary recall. All analysis of energy and nutrient content was completed using Nutrition Data System for Research (NDS-R) version 2005. Results: Two hundred and sixty participants completed the study. LF gained 0.1 ± 3.1 kg, MF gained 0.8 ± 2.5 kg, and HF gained 1.0 ± 2.2 kg and there was no gender or age effect. Longitudinal mixed modeling indicated a significant difference among the groups in weight over time (P = 0.0366). When adjusting for total energy intake, which was a significant predictor of weight over time, the global effect for the group was eliminated. Thus, increasing weight was a function of increasing energy but not increasing percentage of fat intake. Discussion: Energy intake, but not percentage of energy from fat, appears responsible for the observed weight gain. LF diets may contribute to weight maintenance and HF diets may promote weight gain due to the influence of fat intake on total energy intake.
Children's eating behaviors are driven by nutrient needs for growth and health, their development... more Children's eating behaviors are driven by nutrient needs for growth and health, their developmental stage, and by physical and social aspects of the feeding environment. Engendering healthful eating styles requires recognition of children's needs and abilities and a positive, structured environment in which learning and self-regulation are encouraged.
Research conducted in the 1930s showed that, given nutritious choices, children can select an ade... more Research conducted in the 1930s showed that, given nutritious choices, children can select an adequate diet without adult supervision. Paradoxically, children grew well and were healthy despite patterns of intake at individual meals that were unpredictable and highly variable. To investigate in more detail the energy intake of young children, we measured 24-hour food intake for 15 children, from two to five years of age, on six days. For each of the six days of the study, coefficients of variation were calculated for each child for each of the six meals and snacks (breakfast, lunch, dinner, and morning, afternoon, and evening snacks) and for total daily energy intake. The children&#39;s intake at individual meals was highly variable, but total daily energy intake was relatively constant for each child. The mean coefficient of variation for each child&#39;s energy intake at individual meals was 33.6 percent; in contrast, the mean coefficient of variation for each child&#39;s total daily energy intake was 10.4 percent. In most cases, high energy intake at one meal was followed by low energy intake at the next meal, or vice versa. Although children&#39;s food consumption is highly variable from meal to meal, daily energy intake is relatively constant, because children adjust their energy intake at successive meals.
Journal of the American Dietetic Association, 2002
... Debra Sullivan, PhD, RD, Department of Dietetics &amp; Nutrition, University of Kansas ..... more ... Debra Sullivan, PhD, RD, Department of Dietetics &amp; Nutrition, University of Kansas ... Department of Health, Sport and Exercise Sciences, University of Kansas, Lawrence. ... was associate professor, Human Performance Laboratory, University of Nebraska-Kearney, USA. ,; KATE A ...
Background-Early growth monitoring may not identify infants at-risk for later growth faltering be... more Background-Early growth monitoring may not identify infants at-risk for later growth faltering because it is difficult for the provider to recognize how large of a negative shift might be problematic.
Background: Certain individuals appear to be resistant to weight gain in an obesigenic environmen... more Background: Certain individuals appear to be resistant to weight gain in an obesigenic environment, yet the mechanisms for this adaptation are unclear. These individuals may sense positive energy balance more appropriately than those individuals prone to weight gain.
Nearly all Americans (97%) report eating candy at least once per year, yet, on a given fay, only ... more Nearly all Americans (97%) report eating candy at least once per year, yet, on a given fay, only approximately one-fourth of the US population aged ≥2 y consumes candy. Among all Americans, candy contributes a relatively small proportion of calories, added sugars, and saturated fat to the total diet, and recent research suggests that current levels of candy consumption are not associated with risk of weight gain and cardiovascular disease in children and adults. Providing guidance for the consumption of candy in moderation requires and understanding of various behavioral health-related factors that influence candy consumption. A roundtable of behavioral nutrition experts, researchers, and nutrition educators met to discuss recent data on intakes of candy, health outcomes associated with usual candy intake, and the impact of behavioral strategies, including restriction, education, and environmental awareness, on modifying eating behaviors to achieve moderate intakes of candy. Restricting access to palatable foods, whether self-imposed or by parental control, may have potentially negative consequences. Techniques and insight into how to adopt "moderation" in candy consumption, from effective parental practices to environmental strategies that facilitate behavior change without a high degree of effort, were identifies as important next steps towards sustainable dietary guidance related to the role of candy and other treats in a health lifestyle.
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Papers by Susan Johnson