Effects of a low carbohydrate diet on energy expenditure during weight loss maintenance: randomized trial

Abstract

ObjectiveTo determine the effects of diets varying in carbohydrate to fat ratio on total energy expenditure.DesignRandomized trial.SettingMulticenter collaboration at US two sites, August 2014 to May 2017.Participants164 adults aged 18-65 years with a body mass index of 25 or more.InterventionsAfter 12% (within 2%) weight loss on a run-in diet, participants were randomly assigned to one of three test diets according to carbohydrate content (high, 60%, n=54; moderate, 40%, n=53; or low, 20%, n=57) for 20 weeks. Test diets were controlled for protein and were energy adjusted to maintain weight loss within 2 kg. To test for effect modification predicted by the carbohydrate-insulin model, the sample was divided into thirds of pre-weight loss insulin secretion (insulin concentration 30 minutes after oral glucose).Main outcome measuresThe primary outcome was total energy expenditure, measured with doubly labeled water, by intention-to-treat analysis. Per protocol analysis included participants who maintained target weight loss, potentially providing a more precise effect estimate. Secondary outcomes were resting energy expenditure, measures of physical activity, and levels of the metabolic hormones leptin and ghrelin.ResultsTotal energy expenditure differed by diet in the intention-to-treat analysis (n=162, P=0.002), with a linear trend of 52 kcal/d (95% confidence interval 23 to 82) for every 10% decrease in the contribution of carbohydrate to total energy intake (1 kcal=4.18 kJ=0.00418 MJ). Change in total energy expenditure was 91 kcal/d (95% confidence interval −29 to 210) greater in participants assigned to the moderate carbohydrate diet and 209 kcal/d (91 to 326) greater in those assigned to the low carbohydrate diet compared with the high carbohydrate diet. In the per protocol analysis (n=120, P<0.001), the respective differences were 131 kcal/d (−6 to 267) and 278 kcal/d (144 to 411). Among participants in the highest third of pre-weight loss insulin secretion, the difference between the low and high carbohydrate diet was 308 kcal/d in the intention-to-treat analysis and 478 kcal/d in the per protocol analysis (P<0.004). Ghrelin was significantly lower in participants assigned to the low carbohydrate diet compared with those assigned to the high carbohydrate diet (both analyses). Leptin was also significantly lower in participants assigned to the low carbohydrate diet (per protocol).ConclusionsConsistent with the carbohydrate-insulin model, lowering dietary carbohydrate increased energy expenditure during weight loss maintenance. This metabolic effect may improve the success of obesity treatment, especially among those with high insulin secretion.Trial registrationClinicalTrials.gov NCT02068885.

An evidence‐based approach to developing low‐carbohydrate diets for type 2 diabetes management: A systematic review of interventions and methods

“…66 Plausible explanations include the reduction in appetite consistently demonstrated with low-CHO diets that promotes a lower caloric intake in the absence of a specific prescription, 67,68 and the "metabolic advantage" of low-CHO diets that has been shown to significantly increase total energy expenditure to further facilitate weight loss. 69 Furthermore, the present findings suggest that the recommenda- Most vegetables have a low digestible CHO content owing to their high proportions of water and fibre, and often displace the intake of highly processed CHO and discretionary foods. 71,72 Many of the included low-CHO protocols are ultimately in alignment with public health recommendations to consume a vegetable-rich diet for chronic disease prevention and management.…”

“…Although renal outcomes were not included in the present study, a recent systematic review showed no significant difference with regard to several measures of renal function between high‐protein low‐CHO diets and lower‐protein high‐CHO diets . Plausible explanations include the reduction in appetite consistently demonstrated with low‐CHO diets that promotes a lower caloric intake in the absence of a specific prescription, and the “metabolic advantage” of low‐CHO diets that has been shown to significantly increase total energy expenditure to further facilitate weight loss …”

Some Musings About Differential Energy Metabolism With Ketogenic Diets

“…However, it is the other component in the dietary energy equation, the impact on energy expenditure, in which potential differences might afford a unique metabolic benefit to eucaloric or modestly hypocaloric ketogenic regimens. There is evidence that there are modest increases in total daily energy expenditure with lower carbohydrate intakes of lower glycemic index but still not sufficiently low as to be true ketogenic diets . Studies performed with diets that differ in glycemic index and glycemic load but still containing substantial carbohydrate, eliminating the possibility of significant ketonemia, suggest small but important increases in postprandial energy expenditure of about 42 kcal/d that are further increased substantially to 278 kcal/d when carbohydrate intake is decreased from 60% to 20% of energy intake .…”

“…There is evidence that there are modest increases in total daily energy expenditure with lower carbohydrate intakes of lower glycemic index but still not sufficiently low as to be true ketogenic diets . Studies performed with diets that differ in glycemic index and glycemic load but still containing substantial carbohydrate, eliminating the possibility of significant ketonemia, suggest small but important increases in postprandial energy expenditure of about 42 kcal/d that are further increased substantially to 278 kcal/d when carbohydrate intake is decreased from 60% to 20% of energy intake . Although this increase could be in part due to effects on physical activity or the efficiency of energy metabolism in muscle as well, the demonstrated impact on postprandial energy metabolism or diet‐induced thermogenesis strongly indicates that there must be an important impact on general metabolic processes as well.…”

Molecular Mechanism of Functional Ingredients in Barley to Combat Human Chronic Diseases

“…is one of the highest oil-yield crops in the world; however, palm oil is the largest variety of plant oil produced, consumed (30%), and internationally traded in the world, rich in linoleic acid (10%) that is associated with egFAD12 gene [190]. 50~55% carbohydrate diets (especially whole-grain breads, vegetables, and nuts) had minimal risk of mortality [191]. Fruits, vegetables, and whole grains were indispensable among four top diets (Mediterranean diet with five best ranked first, DASH diet with lower blood pressure, Flexitarian diet with lose weight and MIND diet with brain health).…”