Low-carbohydrate diets differing in carbohydrate restriction improve cardiometabolic and anthropometric markers in healthy adults: A randomised clinical trial.

Simon J Thornley,Grant M Schofield,Catherine Crofts,Fabrice L R Merien,Caryn Zinn,Cliff J D C Harvey

doi:10.7717/peerj.6273

Simon J Thornley, Grant M Schofield + Show 4 more

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https://doi.org/10.7717/peerj.6273

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Journal: PeerJ	Publication Date: Feb 5, 2019
Citations: 40	License type: CC BY 4.0

Affiliation: Auckland University of Technology

Abstract

BackgroundLow-carbohydrate, high-fat (LCHF) diets are useful for treating a range of health conditions, but there is little research evaluating the degree of carbohydrate restriction on outcome measures. This study compares anthropometric and cardiometabolic outcomes between differing carbohydrate-restricted diets.ObjectiveOur hypothesis was that moderate carbohydrate restriction is easier to maintain and more effective for improving cardiometabolic health markers than greater restriction.DesignA total of 77 healthy participants were randomised to a very low-carbohydrate ketogenic diet (VLCKD), low-carbohydrate diet (LCD), or moderate-low carbohydrate diet (MCD), containing 5%, 15% and 25% total energy from carbohydrate, respectively, for 12-weeks. Anthropometric and metabolic health measures were taken at baseline and at 12 weeks. Using ANOVA, both within and between-group outcomes were analysed.ResultsOf 77 participants, 39 (51%) completed the study. In these completers overall, significant reductions in weight and body mass index occurred ((mean change) 3.7 kg/m2; 95% confidence limits (CL): 3.8, 1.8), along with increases in high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, (0.49 mmol/L; 95% CL; 0.06, 0.92; p = 0.03), and total cholesterol concentrations (0.11 mmol/L; 95% CL; 0.00, 0.23; p = 0.05). Triglyceride (TG) levels were reduced by 0.12 mmol/L (95% CL; −0.20, 0.02; p = 0.02). No significant changes occurred between groups. The largest improvements in high density lipoprotein cholesterol (HDL-c) and TG and anthropometric changes occurred for the VLCKD group.ConclusionsLow-carbohydrate, high-fat diets have a positive effect on markers of health. Adherence to the allocation of carbohydrate was more easily achieved in MCD, and LCD groups compared to VLCKD and there were comparable improvements in weight loss and waist circumference and greater improvements in HDL-c and TG with greater carbohydrate restriction.

Highlights

The accepted definition for nutritional ketosis (NK) in the clinical nutrition field has become the achievement of !0.5 mmol/L ß- hydroxybutyrate, as the majority of people following a very low-carbohydrate ketogenic diet (VLCKD) achieve this level of blood ketones (Gibson et al, 2015), and this threshold has been used by several studies as an indicator of entry into NK (Guerci et al, 2003; Harvey et al, 2018)
This paper focuses on the key cardiometabolic outcome measures of total cholesterol (Total-c), low density liproprotein cholesterol (LDL-c), high density lipoprotein cholesterol (HDL-c), TG, C-reactive protein (CRP), glucose, and insulin
Of particular interest, was the improvement in waist-height ratio, as this is a strong predictor of all-cause mortality. (Ashwell et al, 2014) We would consider the significant improvements in HDL-c and TG to be clinically meaningful measures of interest when compared to relatively minor changes in Total-c or LDL-c

Summary

Introduction

Low-carbohydrate, high-fat (LCHF) and very low-carbohydrate ketogenic diets (VLCKD) are increasingly used for the management of a range of health conditions, including neurological disorders, obesity, diabetes, metabolic syndrome, and various cancers (Castro et al, 2015; Henderson et al, 2006; Keene, 2006; Kulak & Polotsky, 2013; Lefevre & Aronson, 2000; Levy et al, 2012; Maalouf, Rho & Mattson, 2009; Neal et al, 2008; Paoli et al, 2013; Sumithran & Proietto, 2008; Varshneya et al, 2015) They are used widely in the general population for weight-loss and maintenance, (Bueno et al, 2013) with improved satiety and control of hunger frequently reported by those who adhere to these diets (Johnstone et al, 2008; McClernon et al, 2007; Paoli et al, 2015). Adherence to the allocation of carbohydrate was more achieved in MCD, and LCD groups compared to VLCKD and there were comparable improvements in weight loss and waist circumference and greater improvements in HDL-c and TG with greater carbohydrate restriction

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