Obesity
Conditions
Brief summary
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.
Interventions
BEHAVIORALAdvice on diet, physical activity, and behavior change
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.
BEHAVIORALInstruction in food portion size
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.
OTHERProvision of pre-portioned 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.
BEHAVIORALAdvice on healthy eating for weight loss
Individuals assigned to this program will participate in individual instructional sessions that address principles of healthy eating while on a calorie-restricted diet.
Sponsors
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Penn State University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
FEMALE
Age
20 Years to 65 Years
Healthy volunteers
No
Inclusion criteria
* Body mass index of 28 to 45 kg/m squared * Able to safely engage in physical activity (walking) * Able to attend regular instructional sessions at University Park, Pennsylvania
Exclusion criteria
* have a medical condition diagnosed by a physician that precludes participation * report symptoms indicative of depression or disordered eating * report serious food allergies or intolerance * current or planned participation in a weight-loss program * pregnant or lactating or planning to become pregnant in the next 18 months
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in body weight | Months 0 to 12 | 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 |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Change in portion size consumption | Months 0, 3, 6, & 12 | Portion sizes consumed in various food categories as assessed by diet recalls and diet records |
| Change in blood biomarkers | Months 0, 3, 6, & 12 | Fasting lipids, glucose, insulin, and calculated insulin resistance |
| Change in waist circumference | Months 0, 3, 6, & 12 | — |
| Change in blood pressure | Months 0, 3, 6, & 12 | — |
| Change in portion size selection, perception, and knowledge | Months 0, 3, 6, & 12 | Computerized assessment of various foods (for self-selected portion sizes, estimation of calorie content, and satiety value) and general knowledge about portion size |
| Change in step counts | Months 0, 3, 6, 9, & 12 | Daily step counts from pedometers |
| Change in attitudes and behaviors related to food and eating | Months 0, 1, 3, 6, & 12 | Self-reported eating attitudes and behaviors on multiple questionnaires |
| Change in psychosocial characteristics | Months 0, 3, 6, & 12 | Questionnaires measuring psychosocial characteristics including impulsivity, variety-seeking, and self-efficacy |
| Intervention adherence | Month 12 | Number of sessions attended, number of diet and activity records completed, and frequency of using intervention strategies during the entire trial |
| Change in dietary intakes | Months 0, 3, 6, 9, & 12 | Energy intake, nutrient intakes, dietary energy density, food group intakes, and diet quality from three days of 24-hour diet recalls |
Countries
United States
Outcome results
None listed