The primary aim of this research is to determine the efficacy of two portion-control strategies to achieve sustainable dietary and behavior changes and to promote weight loss and maintenance. A randomized controlled trial will test two approaches to managing portion sizes: one that gives individuals skills and tools to help them make appropriate portion choices, and another that focuses on consumption of pre-portioned foods in order to limit exposure to large portions in the personal food environment. A third group will receive a basic nutritional program to promote weight loss. The second aim of the research is to determine the effects of the programs on knowledge and consumption of appropriate portions, as assessed by innovative assessment methods and multiple-pass dietary recalls. The third aim is to conduct exploratory analyses of individual factors that may influence the response to the portion-control interventions, such as psychosocial indicators, blood biomarkers, and measures of adherence to the interventions. The expected outcome of the project is that it will lead to the development of specific, evidence-based strategies to help control portion sizes in order to manage weight.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
186
Individuals will participate in individual sessions with Registered Dietitians providing basic instruction in principles of weight loss. The program will instruct individuals on the principles of healthy eating and nutrition during calorie restriction. These materials include one module with general information on the importance of limiting portion sizes. The program will also include instruction on physical activity and behavioral strategies for weight loss.
Individuals assigned to this program will participate in individual instructional sessions with specialized materials and tools that address food selection and choosing appropriate portion sizes of various foods.
Individuals assigned to this program will be provided with commercially available pre-portioned foods and will be taught effective ways to incorporate them into their daily diet.
Individuals assigned to this program will participate in individual instructional sessions that address principles of healthy eating while on a calorie-restricted diet.
Penn State University Laboratory for the Study of Human Ingestive Behavior
University Park, Pennsylvania, United States
Change in body weight
Body weight will be measured at multiple time points during the 12-month trial; the main outcome will be the weight trajectory across this time
Time frame: Months 0 to 12
Change in portion size selection, perception, and knowledge
Computerized assessment of various foods (for self-selected portion sizes, estimation of calorie content, and satiety value) and general knowledge about portion size
Time frame: Months 0, 3, 6, & 12
Change in portion size consumption
Portion sizes consumed in various food categories as assessed by diet recalls and diet records
Time frame: Months 0, 3, 6, & 12
Change in blood biomarkers
Fasting lipids, glucose, insulin, and calculated insulin resistance
Time frame: Months 0, 3, 6, & 12
Change in waist circumference
Time frame: Months 0, 3, 6, & 12
Change in blood pressure
Time frame: Months 0, 3, 6, & 12
Change in dietary intakes
Energy intake, nutrient intakes, dietary energy density, food group intakes, and diet quality from three days of 24-hour diet recalls
Time frame: Months 0, 3, 6, 9, & 12
Change in step counts
Daily step counts from pedometers
Time frame: Months 0, 3, 6, 9, & 12
Change in attitudes and behaviors related to food and eating
Self-reported eating attitudes and behaviors on multiple questionnaires
Time frame: Months 0, 1, 3, 6, & 12
Change in psychosocial characteristics
Questionnaires measuring psychosocial characteristics including impulsivity, variety-seeking, and self-efficacy
Time frame: Months 0, 3, 6, & 12
Intervention adherence
Number of sessions attended, number of diet and activity records completed, and frequency of using intervention strategies during the entire trial
Time frame: Month 12
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.