Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Food Science and Human Nutrition


Nutritional Sciences

First Advisor

Lorraine Lanningham-Foster


Valid and reliable dietary assessment methods play a vital role in understanding children’s dietary behaviors and intake. Photo-based visual estimation methods with high flexibility, cost-effectiveness, and lower burden have been developed rapidly and applied widely recently. To promote its further application, it is necessary to perform a systematic analysis to investigate various commonly used visual estimation systems in the context of considering various influencing factors. A photo-based online survey was developed in the first study to evaluate the accuracy of four visual estimation systems: Third, Quarter, Eighth, and Continuous. Participants’ information including sex, age, height and weight, and major background characteristics was collected to explore the effects of these factors on visual estimation accuracy. Overall, the Quarter and Eighth systems had higher accuracy than the Third and Continuous systems. The system accuracy may also be affected by personal- and food-related factors in different ways among the four systems. Additionally, a majority of the survey population (59%) preferred to use the Quarter system for food visual estimations. Therefore, Quarter system was applied to evaluate the effects of SWITCH programming on improving students’ fruit and vegetable consumption (study 2), as well as energy and nutrient intake (study 3). Students in the 5th grade participating in the National School Lunch Program from four elementary schools were involved in both studies. Two schools participated in SWITCH and two did not. Results of the second study demonstrated that students participating in SWITCH significantly increased fruit consumption from 0.37 cups at baseline to 0.50 cups at endpoint. The increase in fruit consumption might potentially enhance students’ nutrient intake during lunch, which was supported by the third study. Students participating in SWITCH significantly increased their fiber selection and decreased their sodium selection and intake. The percentage of students meeting 2010 IOM recommendations for energy and fiber were also increased in SWITCH schools. Findings from this dissertation provide valuable guidance on selecting proper visual estimation systems as well as support the SWITCH program as a promising school wellness initiative to enhance children’s healthy eating and nutrition status.

Copyright Owner

Yuanying Lou



File Format


File Size

237 pages