Changes in Quantity and Sources of Dietary Fiber from Adopting Healthy Low-Fat vs. Healthy Low-Carb Weight Loss Diets: Secondary Analysis of DIETFITS Weight Loss Diet Study.

Joseph Rigdon,Lisa C. Offringa,Jennifer C. Hartle,Christopher D. Gardner

doi:10.3390/nu13103625

Joseph Rigdon, Lisa C. Offringa + Show 2 more

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https://doi.org/10.3390/nu13103625

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Abstract

The daily intake of dietary fiber is well below the recommended levels in the US. The effect of adopting a low-fat vs. a low-carbohydrate weight loss diet on fiber intake is of interest but not well-documented, especially when both approaches promote high-quality food choices. The objective of this paper is to compare the quantity and sources of dietary fiber between a healthy low-fat (HLF) vs. healthy low-carbohydrate (HLC) diet group when consumed over 12 months in a weight loss diet study. In this secondary analysis of the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) study, the amount and sources of dietary fiber were examined in generally healthy adults, 18–50 years of age, Body Mass Index (BMI) 28–40 kg/m2, randomized to HLF or HLC for 12 months, who had available 24-h recalls at 0 (n = 609), 3 (n = 549), 6 (n = 491), and 12 (n = 449) months. The dietary intake was estimated by the Nutrition Data System for Research (NDS-R). The sources of fiber were determined for the major food groups. Significantly more total dietary fiber was consumed by HLF at every post-randomization time point, and, at 12 m, was 23.04 ± 9.43 g vs. 18.61 ± 8.12 g for HLF vs. HLC, respectively, p < 0.0001. In both diet groups at 12 months, the highest amount of dietary fiber came from non-starchy vegetables (4.13 ± 3.05 g and 5.13 ± 3.59 g). The other primary sources of fiber at 12 months for the HLF group were from whole grains (3.90 ± 3.13 g) and fruits (3.40 ± 2.87 g), and, for the HLC group, were from plant protein and fat sources, such as nuts and seeds, their butters, and avocados (2.64 ± 2.64 g). In the DIETFITS study, the difference in the total fiber intake for the HLF vs. HLC groups was more modest than expected. The HLC group consumed reasonably high amounts of fiber from high-protein and high fat plant-based sources.

Highlights

Studies show that high-fiber intakes are associated with reduced rates of cardiovascular disease, cancer, inflammation, diabetes, and obesity [1,2,3,4]
To determine shifts in sources of dietary fiber based on dietary assignment and changes in eating behavior, we investigated food categories modified from the University of Minnesota Nutrition Coordinating Center (NCC) Food Group Serving Count System consumed over the study period (Table S1)
The total fiber intake remained relatively stable for the healthy low-fat (HLF) group, while it decreased for the healthy low-carbohydrate (HLC) group during the study in the context of reduced calorie intake

Summary

Introduction

Studies show that high-fiber intakes are associated with reduced rates of cardiovascular disease, cancer, inflammation, diabetes, and obesity [1,2,3,4]. The fiber intake in the US is substantially below the recommendation of the 2020–2025 Dietary Guidelines for Americans. It is a nutrient of concern, with 90 percent of women and 97 percent of men eating less dietary fiber than recommended [5,6]. According to the National Health and Nutrition Examination Survey (NHANES) from 2001 to 2010, the most common sources of dietary fiber in the US are grain products; only 10% of the grain intake reported was from whole grain sources [8,9]

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