A randomized study of dietary composition during weight-loss maintenance: Rationale, study design, intervention, and assessment

Authors: EBBELING, CARA - Boston Children'S Hospital; KLEIN, GLORIA - Boston Children'S Hospital; LUOTO, PATRICIA - Framingham State College; WONG, JULIA - Boston Children'S Hospital; BIELAK, LISA - Boston Children'S Hospital; EDDY, RALPH - Framingham State College; STELTZ, SARAH - Boston Children'S Hospital; DEVLIN, COURTENAY - Boston Children'S Hospital; SANDMAN, MEGAN - Boston Children'S Hospital; HRON, BRIDGET - Boston Children'S Hospital; SHIMY, KIM - Boston Children'S Hospital; HEYMSFIELD, STEVEN - Louisana State University; WOLFE, ROBERT - University Of Arkansas; WONG, WILLIAM - Children'S Nutrition Research Center (CNRC); FELDMAN, HENRY - Boston Children'S Hospital; LUDWIG, DAVID - Boston Children'S Hospital

Submitted to: Contemporary Clinical Trials
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2017
Publication Date: 12/9/2017
Citation: Ebbeling, C.B., Klein, G.L., Luoto, P.K., Wong, J.M., Bielak, L., Eddy, R.G., Steltz, S.K., Devlin, C., Sandman, M., Hron, B., Shimy, K., Heymsfield, S.B., Wolfe, R.R., Wong, W.W., Feldman, H.A., Ludwig, D.S. 2017. A randomized study of dietary composition during weight-loss maintenance: Rationale, study design, intervention, and assessment. Contemporary Clinical Trials. 65:76-86. https://doi.org/10.1016/j.cct.2017.12.004.

Interpretive Summary: It is well known that people can lose weight but often have a hard time keeping the weight loss over time. In order to keep the weight loss over time, people usually receive lessons on foods and advice on their diets which require a lot of work and often do not work. The possibility that sugar-to-fat content in foods can help keep weight loss over time has not been studied. This paper gave the reasons, the study design, and how we planned to look at the effects of sugar-to-fat content in foods to help keep the weight loss of 164 adults over time. These adults were put on a weight-loss diet to lose 12% of their body weight. They were then put on one of three test diets for 20 weeks followed by 2 weeks of their usual diets. One of the three test diets contained 60% sugar and 20% fat. The second test diet contained 40% sugar and 40% fat. The third test diet contained 20% sugar and 60% fat. We measured their body weights, energy burned at rest and under free-living conditions, physical activity, and disease risk factors before, and after the 20-week test period and after they were on their usual diets for 2 weeks. Once the study data have been analyzed, the results will be presented in another paper.

Technical Abstract: While many people with overweight or obesity can lose weight temporarily, most have difficulty maintaining weight loss over the long term. Studies of dietary composition typically focus on weight loss, rather than weight-loss maintenance, and rely on nutrition education and dietary counseling, rather than controlled feeding protocols. Variation in initial weight loss and insufficient differentiation among treatments confound interpretation of results and compromise conclusions regarding the weight-independent effects of dietary composition. The aim of the present study was to evaluate three test diets differing in carbohydrate-to-fat ratio during weight-loss maintenance. Following weight loss corresponding to 12 +/- 2% of baseline body weight on a standard run-in diet, 164 participants aged 18 to 65 years were randomly assigned to one of three test diets for weight-loss maintenance through 20 weeks (test phase). We fed them high-carbohydrate (60% of energy from carbohydrate, 20% fat), moderate-carbohydrate (40% carbohydrate, 40% fat), and low-carbohydrate (20% carbohydrate, 60% fat) diets, controlled for protein content (20% of energy). During a 2-week ad libitum feeding phase following the test phase, we assessed the effect of the test diets on body weight. The primary outcome was total energy expenditure, assessed by doubly-labeled water methodology. Secondary outcomes included resting energy expenditure and physical activity, chronic disease risk factors, and variables to inform an understanding of physiological mechanisms by which dietary carbohydrate-to-fat ratio might influence metabolism. Weight change during the ad libitum feeding phase was conceptualized as a proxy measure of hunger.