Effective procedures are needed to prevent the substantial increases in adiposity that have been occurring among children and adults. Behavioral change may occur as a result of changes in variables that mediate interventions. These mediating variables have typically come from the theories or models used to understand behavior. Seven categories of theories and models are reviewed to define the concepts and to identify the motivational mechanism(s), the resources that a person needs for change, the processes by which behavioral change is likely to occur, and the procedures necessary to promote change. Although each model has something to offer obesity prevention, the early promise can be achieved only with substantial additional research in which these models are applied to diet and physical activity in regard to obesity. The most promising avenues for such research seem to be using the latest variants of the Theory of Planned Behavior and Social Ecology. Synergy may be achieved by taking the most promising concepts from each model and integrating them for use with specific populations. Biology-based steps in an eating or physical activity event are identified, and research issues are suggested to integrate behavioral and biological approaches to understanding eating and physical activity behaviors. Social marketing procedures have much to offer in terms of organizing and strategizing behavioral change programs to incorporate these theoretical ideas. More research is needed to assess the true potential for these models to contribute to our understanding of obesity-related diet and physical activity practices, and in turn, to obesity prevention.

The relationships among home fruit (F), 100% fruitjuice (J), and vegetable (V) availability and accessibility separately, as reported by 225 fourth- through sixth-grade children and their parents (n = 88), separately, and FJV preferences to child-reported FJV consumption were assessed. For girls, child-reported FJV availability and accessibility accounted for 35% of the variability in FJV consumption. Child-reported availability and parent-reported accessibility were significantly correlated with child FJV consumption in a combined model. For children with high FJV preferences, FJV availability was the only significant predictor, whereas both availability and accessibility were significantly related to consumption for children with low FJV preferences. Interventions targeting child dietary behaviors may need to tailor to the home environment, separately by gender. Extra efforts are necessary by parents to enhance accessibility among children who do not like FJV.

Psychosocial variables that predict dietary behavior become important targets for change in nutrition education programs. Psychosocial variables in models with higher predictability provide more effective levers to promote healthy dietary change. A review of the literature on models with psychosocial variables predicting dietary fat and fruit and vegetable consumption revealed generally low predictiveness, R2 < 0.3 (where R2 is the squared multiple correlation of the statistical model). No single theory provided models that regularly out-predicted others. When models predicted narrower categories of behavior (e.g. milk or salad consumption), predictiveness tended to be higher. Substantial problems were revealed in the psychometrics of both the independent and dependent variables. Little theory-based research has been conducted with adolescents, and the few studies done with children had low predictiveness. In order to increase the predictiveness of models, future research should combine variables from several theories, attend to the psychometrics of all variables, and incorporate variables that moderate the relationship of psychosocial to dietary behavior (e.g. genetics of taste, stage in the life course). Refinements on current research would include longitudinal designs and use of non-self-report methods of dietary behavior to supplement the self-report methods. Improved understanding of dietary behavior should lead to more effective dietary behavior change interventions.

Obesity among children has reached epidemic proportions. Today, an estimated one in four children in the United States is overweight. while 11% arc obese. Children who are overweight tend to remain so up to 20 years of age; in general, they have a 1.5- to twofold higher risk for becoming overweight as adults. The prevalence of overweight has increased approximately twofold in the 20-year period from 1974 to 1994, with the largest increases observed among 19- to 24-year-olds. The annual increases in weight and obesity that occurred from 1983 to 1994 were 50% higher than those from 1973 to 1982. Overweight youth are 2.4 times as likely to have a high serum total cholesterol level, and 43.5 times as likely to have three cardiovascular risk factors. Although the total energy intake of children has remained the same, and the macronutrient density of the diet has changed, the percentage of energy from fat has decreased, while that from carbohydrates and protein has increased. Children have been consuming lower amounts of fats/oils, vegetables/soups, breads/grains, mixed meats, desserts, candy, and eggs. and increasing amounts of fruits/fruit juices, beverages. poultry, snacks, condiments, and cheese. Changes in specific eating patterns may explain the increase in adiposity among children; e.g., increases have occurred in the number of meals eaten at restaurants, food availability, portion sizes, snacking and meal-skipping. Successful prevention and treatment of obesity in childhood could reduce the adult incidence of cardiovascular disease. Because substantial weight loss is difficult to maintain, the prevention of obesity by promoting healthier lifestyles should be one of our highest priorities in the new millennium.

Family, peers and other environmental factors are likely to influence children's dietary behavior but few measures of these phenomena exist. Questionnaires to measure family and peer influences on children's fruit, juice and vegetable (FJV) consumption were developed and pilot tested with an ethnically diverse group of Grade 4-6 children. Principal components analyses revealed subscales with acceptable internal consistencies that measured parent and peer FJV modeling, normative beliefs, normative expectations, perceived peer FJV norms, supportive and permissive parenting practices, food rules, permissive eating, and child food preparation. Internal consistencies were adequate to high, but test-re-test correlations often were low. Children also completed questionnaires on FJV availability and accessibility in the home, and food records for 2 days in the classroom. Parental modeling, peer normative beliefs and FV availability were significantly correlated with FJV consumption. Further research with these scales is warranted.