Obesity is a significant public health issue due to its prevalence and contribution to morbidity and mortality. Obesity prevention efforts in early life are important both because obesity has profound impacts on health status in childhood, and because obesity tracks from childhood to adulthood. The first thousand days in particular – from conception through age two years – may represent a critical period for obesity prevention because taste preferences and metabolic processes are shaped during this period. As such, infant feeding practices – including breastfeeding and complementary feeding practices – may be important predictors of obesity risk. However, there are significant gaps in our knowledge of the relationship between infant feeding practices and childhood obesity. The studies in this dissertation used longitudinal data from the WIC Infant and Toddler Feeding Practices Study-2 (WIC ITFPS-2) to understand the relationship between infant feeding practices - including breastfeeding duration and intensity, timing of introduction of complementary foods, and early introduction of sugar-sweetened foods and beverages - on weight trajectories and odds of overweight and obesity among low-income children up to age 3 years. Study 1 examined the relationship between breastfeeding duration and weight trajectories from age 6 months to 3 years and odds of overweight/obesity at ages 2-3 years. Mixed-effects regression models indicated that any breastfeeding (exclusive or partial) for at least 6 months and exclusive breastfeeding for at least 3 months were associated with healthier weight trajectories among both boys and girls. Breastfeeding was associated with significantly reduced odds of overweight/obesity for girls but not boys. Compared to girls who were never breastfed, those who were breastfed at all for less than 6 months had 45% lower odds of overweight/obesity while those breastfed at all for 6 months or longer had 65% lower odds of overweight/obesity. Compared to girls who were never exclusively breastfed, girls exclusively breastfed for less than 3 months had 46% lower odds of overweight/obesity and those exclusively breastfed for 3 months or more had 78% lower odds of overweight/obesity. There was evidence of a dose-response relationship between breastfeeding duration and intensity among girls. Compared to girls who were never breastfed, those breastfed for less than 3 months (short duration) had 39% lower odds of overweight/obesity, those partially breastfed for at least 3 months (longer duration, low intensity) had 55% lower odds of overweight/obesity, and those exclusively breastfed for at least 3 months (longer duration, higher intensity) had 79% lower odds of overweight/obesity. Study 2 examined the relationship between timing of introduction of complementary foods and weight trajectories from age 6 months to 3 years and odds of overweight/obesity at ages 2-3 years. Mixed-effects regression models indicated differences in weight trajectories by timing of introduction of complementary foods which varied by sex. Compared to complementary food introduction at 4-6 months, late introduction to complementary foods (at or after 7 months) was associated with less healthy weight trajectories among boys, while early introduction (<4 months) was associated with less healthy weight status among girls. However, there was no difference in odds of overweight/obesity at ages 2-3 years by timing of introduction of complementary foods among boys or girls. There was similarly no evidence that the effect of timing of introduction of complementary foods on odds of overweight/obesity differed by breastfeeding duration. Study 3 examined the relationship between early introduction to sugar-sweetened foods and beverages and weight trajectories from age 6 months to 3 years and odds of overweight/obesity at ages 2-3 years. Mixed-effects regression models indicated no difference in weight trajectories or odds of early childhood overweight/obesity between children who received soda, other sugar-sweetened beverages, or sweets such as cake or cookies before 1 year of age compared to those who didn’t receive these sugar-sweetened foods and beverages until 1 year of age or later. The three studies contribute to our understanding of the relationship between infant feeding practices and weight trajectories in early childhood. These findings suggest that longer durations of breastfeeding may be beneficial in establishing healthy weight trajectories and preventing overweight/obesity in early childhood and have important implications for policy and practice. Key policy, systems, and environmental change strategies that may improve breastfeeding initiation and duration among low-income mothers in the U.S. include a) adoption by Local WIC Agencies of evidence-based, culturally tailored participant education focused on breastfeeding promotion; b) an increase in the proportion of hospitals with Baby Friendly designation; c) paid family leave for 12 weeks following the birth of a child; and d) expansion of workplace lactation accommodation policies to cover all mothers in the workplace. Ultimately, improving breastfeeding outcomes among mothers and infants participating in the WIC program may significantly reduce the racial/ethnic and socioeconomic disparities in childhood obesity in the U.S.

The prevention and control of chronic diseases remains an important public health issue due to their contribution to worldwide morbidity and mortality and the considerable social and economic costs associated with these conditions. Early adolescence is a critical period for fostering healthy habits associated with chronic disease prevention, including physical activity and eating a healthy diet. Physical activity and diet are frequent targets of school-based public health programs because early adolescents spend a large portion of their time in the school setting and are shaped by processes in this social context. However, current trends in public education have resulted in the de-prioritization of issues not directly related to school accountability and academic achievement. As such, health promotion efforts are often cobbled together in non-institutionalized ways and there is incomplete understanding of the influence of the broader school health environment on early adolescents’ health behaviors.

Using a mixed methods approach, three separate but related studies were conducted in order to understand the relationship between the school health environment and early adolescent health behaviors related to long-term chronic disease prevention. The research was guided by the Biopsychosocial Model of Adolescent development, Ecological Systems Theory, and the life course perspective, focusing on both individual and contextual factors that shape behavior.

The first study examined changes in and determinants of early adolescents’ physical activity and dietary behaviors during middle school. This study used quantitative, longitudinal data (i.e., surveys conducted during students’ 7th and 8th grade years) from Project SHAPE, a school-based intervention study. In general, this study found that participation in daily physical activity and consumption of fruits and vegetables was low in both seventh and eighth grade. In addition to the low rates themselves, declines in physical activity and diet quality during this period were also a cause for concern. This study found, on average, a 7.2% decline in the number of days of 60 minutes of physical activity among girls, a 5.3% decline in the number of days of muscle-strengthening physical activity among boys, and a 17% decline in the number of days of muscle-strengthening physical activity among girls. Individual- and school-level factors helped to explain the changes in physical activity and dietary behaviors from seventh to eighth grade found in this study.

Using the same Project SHAPE data from 8th grade only, the second study examined the relationship between the perceived school health environment and early adolescents’ physical activity and dietary behaviors. This study found that few eighth grade students met recommendations for daily or muscle-strengthening physical activity, that intake of fruits and vegetables was also below recommendations, and that intake of unhealthy food items (i.e., soda, diet soda, sugar-sweetened beverages, salty snacks, sweets, and fast food) was high relative to healthy food intake. Differences in these behaviors were observed by individual- and school-level factors. On average, students’ perceptions of the school health environment were quite low (3.9 out of 9), suggesting that they did not find the environment to be supportive of healthy behaviors. No individual factors were found to be associated with these perceptions in this study. More positive perceptions of the school health environment were associated with a higher likelihood of meeting the muscle-strengthening physical activity recommendation and marginally associated with a higher likelihood of meeting the daily physical activity recommendation. Depending on the level of meal program participation at the school, more positive perceptions of the school health environment were also associated with higher intake of fruit and vegetables, but were not associated with intake of unhealthy food items.

The third study investigated educators’ perspectives on the ways in which schools influence the health of early adolescents. This study used additional qualitative data collected from staff and administrators from the same Project SHAPE study schools. Several of the findings of this study were related to the perception that students today are growing up in a “different world” than the one interviewees themselves had experienced in childhood and adolescence, and these perceptions factored into the ways in which interviewees conceptualized health and safety at school. For example, interviewees described observing high levels of stress, anxiety, and trauma among their student populations. Interviewees described an increase in conversation or action around mental health and social emotional learning in their schools; however, there were also several examples of ways in which health promotion was de-prioritized at the school, even for administrators who strongly believed it was important. Physical education (PE) and provision of food at school were by and large viewed as the two main sources of health promotion in the school. However, interviewees also brought up a plethora of issues associated with PE and school meals, such as having class time taken away from PE or students not liking the food provided. Overall, interviewees felt that in an ideal world, health promotion would be naturally and implicitly woven in to the culture and mission of the school.

Findings of the three studies contribute to our understanding of the school health environment, including the ways in which both physical and social aspects of the environment are associated with early adolescents’ health behaviors.

The extent to which climate change will exacerbate already growing inequality, both across and within locations, is an open question. The power that people have, or lack, to adapt to a warming climate is central to this issue. This dissertation includes three studies on potential climate adaptations. In the first, my coauthors and I study whether heat-induced use of energy-intensive adaptation technologies, such as air conditioning, can lead to financial distress. We test for this possibility with data from California on electricity use and disconnections, a consequence of utility bill non-payment. We find that hot weather increases electricity expenses in the current billing period and the relative risk of disconnection 51 to 75 days later. In the second study, my coauthors and I examine the impact of temperature-related crop losses on household diets in rural India, a setting with a high prevalence of small family farms. High temperatures during the growing season reduce crop yields, but it is unclear how these losses affect household diets. While we find no significant impact of heat on average calorie or iron consumption in the subsequent year, the number of extremely malnourished households increases. We also find suggestive evidence that households adapt to heat-induced losses of home-grown calories by purchasing more food, which helps to explain the lack of aggregate impacts. In the third study, I analyze worker responses to climate change. Past work in this area has largely focused on the on-the-job effects of extreme weather on environmentally exposed workers and potential short-term adaptations. Little is known about long-term adaptations, such as changing occupations. Well-documented challenges to occupational mobility, especially between occupations with different task requirements, suggest that this adaptation strategy may be prohibitively costly for many workers. Using individual-level panel data from France, I find that historically, inter-exposure mobility rates are low. The task composition of high exposure jobs provides a partial, but incomplete, explanation for this labor market segmentation.

The dissertation examines the influences on and implications of food banks’ efforts to improve the healthfulness of food distributed at food banks through an embedded mixed- methods approach consisting of two interrelated studies. Guided by Resource Dependence Theory, Diffusion of Innovation Theory, and the Social Ecological Model, the research considered both organizational and contextual factors that shape organizational behavior.

Study One examined the determinants of nutrition policy and practice adoption among food banks and the relationship of policy and practice adoption to nutritional quality of food bank inventory using data collected in the 2017 MAZON National Food Bank Survey Assessment of Nutrition Practices and Policies as well as other publicly available data. Study results showed that organizational and contextual characteristics of food banks helped to explain the adoption of nutrition-based food banking strategies and measures of inventory quality.

Study Two explored how organizations within the charitable food system responded to recent trends to improve the nutritional quality of food bank inventory using data collected from a descriptive case study with an adopter and non-adopter food bank and in-depth interviews with representatives from nation-level key stakeholders. National stakeholders in the charitable food system described a sense of progress that had been made in recent years to promote the distribution of healthier foods both ideologically and operationally. Despite this progress, participants reported continued challenges embedded in the structure of the charitable food system that would continue to make the distribution of nutritionally dense foods difficult. With respect to the case study, findings showed that despite differences in nutrition-strategy adoption status, both case study sites were actively prioritizing the sourcing and distribution of healthier foods. Relationships were a central focus of the organizations’ work and the interviewees at food banks were focused on the need to develop pantries for the changing inventory streams.

Overall, the findings from this dissertation used multiple perspectives to advance our understanding of healthy eating promotion at food banks with the anticipation that improving the nutritional quality at food banks will have ripple effects throughout the charitable food system.

Early life adversity exposing vulnerable individuals to potential harm during the first 18 years of life increases the risk for a wide range of adverse physical and mental health outcomes. Childhood adversity is an example of a public health problem that requires “systems thinking” through consideration of social, environmental, familial, psychological, and biological/genetic factors. Understanding the mechanisms of these complex concepts and synthesizing this information into a comprehensive model is necessary.

The widely accepted Adverse Childhood Experience (ACE) measure captures exposure to childhood maltreatment and household dysfunction. ACEs have been shown to associate with nonspecific risk for a wide range of adverse mental health conditions across all socioeconomic groups. Using a social determinants of health framework, ACEs can be viewed as a consequence of upstream vulnerability factors that are structural (i.e., rooted in cumulative disadvantage when families face socioeconomic and relational adversity). ACEs can also be viewed as a psychosocial risk factor impacting mental health independent of other social patterns (e.g., among those with higher socioeconomic status).

Although sexual minority groups appear disadvantaged concerning both ACE exposure and mental health outcomes, the literature describing links between ACEs and mental health is limited among men who have sex with men (MSM), particularly those of low-income and minoritized status. The primary research aim in this dissertation is to investigate if exposure to ACEs (recalled from the first 18 years of life) predict poor mental health outcomes (drug use, depressive and anxiety symptoms) among mostly Black and Latino low-income MSM in adulthood, adjusting for a wide range of sociodemographic and behavioral factors. This research question was explored in three separate studies, based on a Life Course Perspective. Each study examined the cumulative ACE score, dimensional approaches (separating ACEs into categories of childhood maltreatment and household dysfunction), and selective approaches (considering individual ACEs) on these mental health outcomes. All studies investigated whether specific resilience factors (i.e., perceived social support, and sleep quality) buffer the hypothesized associations between ACEs and mental health through effect modification (i.e., moderation).

Data for this dissertation comes from the mSTUDY (Men Who Have Sex with Men and Substance Use Cohort at UCLA Linking Infections, Noting Effects [MASCULINE]), a longitudinal study of HIV-positive and HIV-negative MSM with varied substance use behaviors. Participants were assigned male sex at birth, English-speaking, ages 18-45; and if HIV-, reported having sex with men in the past twelve months (n=297). Multilevel commands using participant ID were used for mixed effects in random intercept logistic and ordinal regression models.

The results of this research suggest that ACEs have significant associations with mental health during adulthood among mostly Black and Latino low-income MSM in Los Angeles. While relationships between ACEs and mental health are well documented, evidence linking these among MSM is sparse, particularly among those with multiple forms of cumulative disadvantage. In this research, the total ACE score predicted depressive and anxiety symptoms, and the outcome of self-reported drug use trended toward significance. The dimension of childhood maltreatment predicted depressive and anxiety symptoms, but not drug use. Selective approaches identified that childhood sexual abuse predicts depressive symptoms; and emotional neglect predicts anxiety. Only the association between childhood sexual abuse and depressive symptoms survived adjustment for the other nine ACEs.

Perceived social support emerged as a buffering factor for drug use in the cumulative and selective approaches. Sleep quality did not emerge as a resilience factor (moderator) for any outcomes of depressive and anxiety symptoms, suggesting that the association between ACEs and these outcomes did not differ by sleep quality. This dissertation’s findings contribute to our understanding of how ACEs might impact mental and behavioral health outcomes among socially disadvantaged MSM. One limitation is that the sample was not randomly selected. Several recommendations for future research (including ACE measurement) are proposed.

Current dietary patterns threaten human and planetary health. In the United States, individuals must shift to dietary patterns higher in plant-based foods and lower in animal-based foods to reduce chronic disease risk and maintain stability of the Earth system. Despite high scientific agreement that we can simultaneously improve health and environmental sustainability through dietary shifts, interventions targeting these dual outcomes remain understudied. This dissertation employed a community-based participatory research approach to investigate how academics and non-academic foodservice leaders can collaborate to address gaps in the development, implementation, and evaluation of interventions to promote healthier, more environmentally sustainable diets. Research was focused on the university setting and took place at the University of California, Los Angeles.

Guided by the diffusion of innovation framework, Study One qualitatively described and examined the process of developing and implementing the Impossible™ Foodprint Project—an intervention to reduce animal-based protein consumption in university dining. Intervention components included: 1) the addition of new menu items with Impossible™ plant-based meat, and 2) a complementary social marketing campaign framed around climate change. Findings from Study One highlight the value of the university’s involvement in existing health and sustainability initiatives for intervention agenda-setting and collaboration among academics and non-academic partners. In addition, results suggest university foodservice leaders may be particularly open to strategies such as piloting new menu items and providing education—rather than taking existing menu options away. Furthermore, co-creation of intervention materials and feedback from multiple data sources enhanced capacity for foodservice leaders to expand efforts to promote low-carbon-footprint foods. Lack of coordination with restaurant operators emerged as a barrier to initial implementation of the social marketing campaign, while cost prevented scale-up of Impossible™ menu items beyond the pilot intervention restaurant.

Study Two utilized routinely collected sales and nutritional data from FoodPro, a widely used foodservice data management platform. A natural experiment with a pre-post non-equivalent comparison group design was used to evaluate 1) whether the Impossible™ Foodprint Project intervention met foodservice leaders’ goal of reducing animal-based entr�e sales, and 2) the impact of the intervention on the healthfulness and environmental sustainability of entr�es sold. The analytic sample included 645,822 entr�es sold at the three study sites during the Fall 2018 (pre) and Fall 2019 (post) academic quarters. During the post period, new menu items with Impossible™ plant-based meat comprised over 11% of entr�e sales at the intervention site. At the same time, the proportion of animal-based entr�e sales decreased by 9% (raw change 7%, 83% to 76%), a significantly greater decrease than the two comparisons sites.

Healthfulness was operationalized as a decrease in the proportion of red meat entr�es sold and improvement in the nutritional quality of entr�es sold. While the proportion of red meat entr�es sold significantly decreased by about 8% at the intervention site (raw change 4%, 45% to 41%), a similar decrease was observed at one of the comparison sites, resulting in an unclear intervention effect. Small but statistically significant nutritional changes were observed at the intervention site: On average, each entr�e sold contained 21.3 fewer calories (kcal) and lower quantities of nutrients of concern: 0.2 fewer g saturated fat and 26.9 fewer mg sodium. Quantities of other nutrients also decreased: 0.7 fewer g protein, 0.1 fewer g fiber, and 1.5 fewer g unsaturated fat. However, nutritional outcomes varied when stratifying by entr�e type (i.e., build-your-own vs. special), resulting in a conditional assessment of the intervention’s nutritional impacts, described within.

Environmental sustainability was operationalized as reduction in climate impact level (low, medium, high) and carbon footprint of entr�es sold. There were clear positive intervention effects on these outcomes. For example, the proportion of low-impact entr�e sales increased by over 50% at the intervention site (raw change 7%, 14% to 21%), a significantly greater increase than the two comparison sites. This corresponded with an 8% decrease in the mean carbon footprint of each entr�e sold at the intervention site, from 1,522 to 1,405 g CO2-equivalent (117 g decrease). With 141,321 entr�es sold at the intervention site in Fall 2019, this equates to approximately 16.4 metric tons of CO2 saved—the equivalent of driving 42,000 miles.

In line with foodservice leaders’ priorities, we also conducted a brief customer survey (n=215). Results suggest a diverse range of students was open to trying the new Impossible™ menu items, and customer satisfaction was high. In comparing one-time versus repeat consumers, we found significant differences across most behavioral and cognitive factors measured. In general, repeat consumers reported consuming less animal-based protein and were more likely to believe Impossible™ is delicious and a satisfying alternative to animal meat. We also found evidence that values and race/ethnicity may affect beliefs about the sensory experience of eating Impossible™, which in turn affects repeat consumption.

Finally, Study Three utilized a true experiment through Qualtrics to test whether environmental sustainability framing is more effective than health framing in “nudging” university consumers to choose a plant-based menu option. Participants were randomly assigned to one of three menu framing conditions—control (no framing), health framing, and environmental sustainability framing—and given the choice between chicken enchiladas and plant-based tacos. Of the 450 participants recruited for the study, 437 were maintained in the analytic sample, including 352 (79%) undergraduate students and 85 (21%) university staff. There were no statistically significant differences in choice across menu framing conditions. Approximately 39% of participants chose the plant-based tacos in the control condition, 36% in the health framing condition, and 40% in the environmental sustainability framing condition. In short, we found no main or conditional effects of environmental sustainability framing, compared to control. In contrast, we found some evidence that, compared to control, health framing may have negative effects among some subgroups, including university staff. Despite observed null effects of environmental sustainability framing, this approach may still be preferable to health framing given potentially counteractive health framing effects. In ancillary analyses described within, we found that, compared to health framing, environmental sustainability framing may improve anticipated enjoyment of a plant-based dish—even if it does not affect choice.

In sum, Study One sheds light on how and why interventions take shape, with an emphasis on collaboration between academic and non-academic foodservice partners. Study Two provides novel insight into the benefits and tradeoffs of promoting low-carbon-footprint foods and introducing new plant-based meat alternatives into institutional food environments. Experimental findings from Study Three suggest some nudges may be insufficient to affect choice of a plant-based menu item, while others may be counteractive. Taken together, results of this dissertation build capacity for academics and foodservice leaders to advance intervention action and research to improve human and planetary health through food.

Objective

Design

Subjects

Results

Conclusions

Adolescents spend almost nine hours a day engaging with media. As a result, they are confronted with large amounts of obesogenic content that shapes their understanding of what are normal and acceptable eating behaviors. Utilizing primary data collected from a sample of 4,838 low-income, racially and ethnically diverse middle school students in Los Angeles County, I studied the effects of different types of media use (i.e., social media, TV/movies/videos, gaming, music, Internet) on dietary patterns and weight outcomes. I assessed (1) whether those effects were mediated by individual-level health behaviors (i.e., snacking while consuming media, sleep duration, physical activity); and (2) whether it was possible to buffer the deleterious effects of media consumption on eating behaviors by associating with friends who are perceived to place importance on eating healthfully, friends who are perceived to be dieters, or by having classmates who eat more healthfully, or by having classmates who are on average slim. I also examined social media specifically and assessed whether the effects on dietary behaviors were exacerbated for individuals who perceive themselves to be overweight or are trying to lose weight. In this way, I was able to gain a clearer picture of the social and environmental determinants of obesity risk in adolescents.

I found that media consumption is consequential to the diet of middle school students. This was a robust finding. Independent of health behaviors, friends, classmates, weight status, and dieting behaviors, media consumption was associated with poor eating outcomes. Media consumption generally results in greater consumption of sugar-sweetened beverages, junk food and fast food and less consumption of fruits and vegetables. Strong support emerged that snacking on junk food while consuming media complements other unhealthful eating behaviors. There was relatively weak evidence that sleep duration or physical activity explained the relationship between media consumption and eating behaviors. Furthermore, I looked at contextual factors and showed that friend and classmate behaviors matter independent of media consumption. That is, one’s social networks contribute to poor dietary behaviors. Finally, I examined social media use specifically and found that it was associated with poor dietary behaviors for both males and females. There was also weak evidence to suggest dieting buffers the deleterious effects of social media on eating behaviors for males. But more importantly, weight-related concerns and weight control behaviors served to restrain consumption of excess discretionary calories that come from things like sugar-sweetened beverages, junk food and fast food independent of social media consumption.

Understanding and addressing determinants of eating behaviors is of critical importance. In a complex society where youth are confronted with obesogenic content in media, peer influences, and other socio-ecological factors, it is no wonder that obesity among young people is a complex and difficult issue to address. It will not be until more multi-level and well-informed public health efforts are implemented that any real change can be made in the eating behaviors and health outcomes of our youth. If this does not happen, it is unlikely that we will be able to halt or reverse the obesity epidemic among youth.

Objective

Design

Setting

Participants

Results

Conclusion

Purpose

Methods

Results

Conclusions