December 2011

Dietary Intakes Associated with Successful Weight Loss and Maintenance during the Weight Loss Maintenance Trial

Catherine M. Champagne, Stephanie T. Broyles, Laura D. Moran, Katherine C. Cash, Erma J. Levy, Pao-Hwa Lin, Bryan C. Batch, Lillian F. Lien, Kristine L. Funk, Arlene Dalcin, Catherine Loria, Valerie H. Myers

Obesity is no stranger in the United States. According to prevalence data from the National Health and Nutrition Examination Survey, it is predicted that 80% of Americans will be either overweight or obese by the year 2026. To date, many research studies have concluded that there are a variety of dietary strategies focused on macronutrient distribution that have positive weight loss effects. However, limited research is available on approaches toward weight loss maintenance and relapse prevention, specifically ones tailored to the individual. The purpose of this study served threefold: to provide additional evidence to existing literature on macronutrient composition specific to a diverse population; to determine which changes in dietary consumption of macronutrients, fruits, vegetables, low-fat dairy and dietary fiber were associated with weight loss during the weight loss phase of the trial (Phase I); and to determine which changes in macronutrients, fruits, vegetables, low-fat dairy and dietary fiber consumption were associated with weight maintenance across a 30-month period (Phase II).

Funded by the National Heart, Lung, and Blood Institute, the study included 1,032 at-risk for cardiovascular disease participants from four regions of the US (Baton Rouge, LA, Portland, OR, Baltimore, MD, and Durham, NC). A FFQ was given to participants at the initiation of Phase I in addition to the assessment of weight and BMI. Phase I began with individual instruction on the DASH diet with emphasis on increasing consumption of fruits and vegetables, low-fat dairy and whole grains. After six months, participants were allowed to enter Phase II if a weight loss minimum of 4 kg had been achieved. Data on height, weight, and dietary intake information was also collected at baseline (beginning of Phase II), 12 months post baseline, and 30 months post baseline. Of the participants in Phase I and II, 828 completed the FFQ at all four time points. Descriptive statistics were used to summarize the data: total number of participants, those completing the FFQ, age, ethnicity, educational level, and household income. Changes in weight, BMI, and dietary intake were defined by the difference between the start and end of each measurement time period. Linear regression models were used to observe the relationship between changes in dietary intake and changes in weight during Phase I (6 months) and II (30 months) and were adjusted for site, age, physical activity, race, sex, and race-sex interaction. Additionally, changes in macronutrient intake and different food group intakes were examined using multivariate models.

After Phase I, participants experienced on average a significant decrease in weight (-8.4±0.1 kg). However, during the 30-month Phase II maintenance period, participants on average regained 52% of weight lost during Phase I. This corresponded to an overall average weight loss maintenance of -4.0±0.2 kg. In both phases, substitution of carbohydrates for fat, substitution of protein for fat, substitution of protein for carbohydrates, and increasing intake of fruits and vegetables were associated with significant weight loss. Increasing dairy intake was associated with significantly less weight gain in Phase II, but not significant weight loss in Phase I. Increasing dietary fiber was not associated with weight loss during either phase of the study. Substituting protein for fat was associated with the largest weight loss changes during Phase I and considerable weight loss changes in Phase II. Regarding the three food group changes, increasing consumption of fruits and vegetables was associated with the largest 6-month weight change during Phase I (-0.29 kg per 6 months per +1 serving), while increasing consumption of dairy products was associated with the largest 6-month weight change during Phase II (-0.17 kg per 6 months per +1 serving).

Due to its large, diverse sample size this study pioneered comparisons between race, sex, and race-sex relationships. African-American men decreased their percentage of protein intake while other groups increased and it was also noted that this subset population did not decrease the percentage of energy from fat (compared to non-African Americans). Men increased fiber more than women; however increase of fruit and vegetable intake was observed regardless of sex. This suggests that men may desire increase in dietary fiber from sources other than fruits and vegetables. It was also observed that African Americans did not increase fruit and vegetable intake as much as non-African Americans. Even though % of energy increases in protein and % of energy decreases in fat were observed throughout the study, these levels still did not meet the recommended macronutrient levels of the DASH diet. The researchers suggested that participants may have experienced difficulty with dietary adherence long-term due to reductions in dietary fat and not enough increase in dietary protein. These results suggest that culturally specific, tailored dietary recommendations, based on preferences for more satiating foods, may be beneficial in weight loss promotion and weight loss maintenance in Americans.

Champagne, C.M., et al. (2011). Dietary intakes associated with successful weight loss and maintenance during the weight loss maintenance trial. Journal of the American Dietetic Association, 111(12), 1826-1835.