December 2011
Catherine M. Champagne, PhD, RD, LDN, FADA, Professor-Research, Stephanie T Broyles, PhD, Assistant Professor, Laura D. Moran, MS, RD, LDN, Clinical Dietitian, Katherine C. Cash, RD, LDN, Research Dietitian/Interventionist, Erma J. Levy, MPH, RD, Research Dietitian/Interventionist, Pao-Hwa Lin, PhD, Associate Research Professor, Bryan C. Batch, MD, Lillian F. Lien, MD, Medical Director, Duke Inpatient Diabetes Management, Assistant Professor, Department of Medicine, Kristine L. Funk, MS, RD, Research Associate III, Arlene Dalcin, RD, LDN, Research Associate, Catherine Loria, PhD, MS, MA, FAHA, Nutritional Epidemiologist, and Valerie H. Myers, PhD, Instructor, Behavioral Medicine

 

Abstract

Background

Dietary components effective in weight maintenance efforts have not been adequately identified.

 

Objective

To determine impact of changes in dietary consumption on weight loss and maintenance during the Weight Loss Maintenance (WLM) clinical trial.

 

Design

WLM was a randomized controlled trial. Successful weight loss participants who completed Phase I of the trial and lost 4kg were randomized to one of three maintenance intervention arms in Phase II and followed for an additional 30 months.

 

Participants/setting

The multicenter trial was conducted from 2003–2007. This substudy included 828 successful weight loss participants.

 

Methods

 

Dietary Measures

The Block Food Frequency Questionnaire (FFQ) was used to assess nutrient intake levels and food group servings. Carbohydrates, proteins, fats, dietary fiber and fruit/vegetable and dairy servings were utilized as predictor variables.

 

Data collection

The FFQ was collected on all participants at study entry (beginning of Phase I). Those randomized to Phase II completed the FFQ at three additional time points; randomization (beginning of Phase II), 12 and 30 months.

 

Intervention

The main intervention focused on long term maintenance of weight loss using the Dietary Approaches to Hypertension (DASH) diet. This substudy examined whether changes to specific dietary variables were associated with weight loss and maintenance.

 

Statistical analyses performed

Linear regression models that adjusted for change in total energy examined the relationship between changes in dietary intake and weight for each time period. Site, age, race, sex, and a race-sex interaction were included as covariates.

 

Results

Participants who substituted protein for fat lost, on average, 0.33 kg per 6-months during Phase I (p<0.0001) and 0.07 kg per 6-months during Phase II (p<0.0001) per 1% increase in protein. Increased intake of fruits and vegetables was associated with weight loss in Phases I and II: 0.29 kg per 6-months (p<0.0001) and 0.04 kg per 6-months (p=0.0062), respectively, per 1-serving increase. Substitution of carbohydrates for fat and protein for carbohydrates were associated with weight loss during both phases. Increasing dairy intake was associated with significant weight loss during Phase II (−0.17 kg per 6-months per 1-serving increase, p=0.0002), but not in Phase I. Dietary fiber revealed no significant findings.

 

Conclusion

Increasing fruits, vegetables, and low-fat dairy may help achieve weight loss and maintenance.