Abstract P214: Dietary Adherence and Dietary Quality Are Associated With Weight Loss Success Among Those Following Low-fat and Low-carbohydrate Diets

Abstract

Introduction: Dietary modification is the cornerstone of most successful weight loss strategies. Low-fat and low-carbohydrate diets are among the most studied approaches, but neither has been shown to be consistently superior for weight loss in the general population. Previous studies suggest that eating a high-quality diet or adhering to a given dietary strategy may influence weight loss, however these two factors have not been examined concurrently for those following macronutrient-limiting diets. Objective: To determine whether improvement in dietary quality, change in dietary macronutrient composition or the combination of these factors leads to differential weight loss for those instructed to follow a healthy low-fat (HLF) or healthy low-carbohydrate (HLC) diet. Methods: Generally healthy, non-diabetic adults, aged 18-50 years, BMI 28-40 kg/m 2 , were randomized to HLF or HLC diets for 12 months (n=609) as part of the DIETFITS weight loss study. Participants that provided complete 24-hour dietary recall data at baseline and 12 months were included in this secondary analysis (n=448; n=224 HLF, n=224 HLC). Within each diet assignment arm, our analysis divided participants into four subgroups according to 12-month change in diet quality score (HEI-2010, above the median was defined as high quality (HQ); below the median was defined as low quality (LQ)) and 12-month change in macronutrient intake (below the median was defined as high adherence (HA) and above the median was defined as low adherence (LA) for fat (g) or digestible carbohydrate (g) for HLF and HLC, respectively). Multiple linear regression adjusted for age, sex, baseline weight and baseline fat (or digestible carbohydrate) intake was used to compare the primary outcome, baseline to 12-month change in mean BMI (kg/m 2 ), for those in the HQ/HA, HQ/LA, LQ/HA subgroups versus the LQ/LA subgroup within HLF and HLC. Results: For HLF, changes (95% CI) in mean BMI were -1.11 kg/m 2 (-2.10, -0.11) for HQ/HA, -0.26 (-1.26, 0.75) for HQ/LA, and -0.66 (-1.74, 0.41) for LQ/HA compared with the LQ/LA subgroup. For HLC, changes (95% CI) in mean BMI were -1.15 kg/m 2 (-2.04, -0.26) for HQ/HA, -0.30 (-1.22, 0.61) for HQ/LA, and -0.80 (-1.74, 0.14) for LQ/HA compared with the LQ/LA subgroup. Conclusions: Within both the HLF and HLC diet arms, the 12-month decrease in BMI was significantly greater for those in the High Quality/High Adherence subgroups relative to the Low Quality/Low Adherence subgroups. Neither High Quality nor High Adherence alone were significantly different than the Low Quality/Low Adherence subgroups. While further investigation is needed, the results of this secondary analysis support the importance of the combination of dietary adherence and high-quality diets for weight loss.