RT Journal Article
SR Electronic
T1 Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men: a secondary analysis of energy expenditure and physical activity
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 383752
DO 10.1101/383752
A1 Mark I. Friedman
A1 Scott Appel
YR 2018
UL http://biorxiv.org/content/early/2018/08/06/383752.abstract
AB Background Hall et al. (1) tested competing models for the etiology of obesity by measuring the change in energy expenditure (EE) of overweight and obese subjects after they were switched from a baseline high-carbohydrate diet (BD) to an isocaloric low-carbohydrate ketogenic diet (KD). EE measured using metabolic chambers increased transiently and by what was considered a relatively small extent after the switch to the KD, whereas EE measured using doubly labeled water (EEDLW) after the response in the chambers had waned increased more substantially.Objective Using the publicly available Hall et al. dataset, we examined the effect of housing conditions on the magnitude of the increase in EEDLW after the switch to the KD and the role of physical activity in that response.Design The 14-day EEDLW measurement period included 4 days when subjects were confined to chambers instead of living on wards. To determine the effect on EEDLW only for the days subjects were living on the wards, we used a formula in Hall et al. to calculate non-chamber EE (EEnonchamber). In keeping with best practices, we calculated 14-day EEDLW and EEnonchamber with and without data from a statistically identified outlier. To assess the role of physical activity in the increase in EEDLW after the switch to the KD, we analyzed accelerometer data collected during the BD and KD EEDLW measurement periods.Results In comparison with the increase in 14-day EEDLW of 151 kcal/d ± 63 (P = 0.03) after the switch to the KD, EEnonchamber increased by 203 ± 89 kcal/d (P = 0.04) or, with inclusion of the outlier, by 283 ± 116 kcal/d (P = 0.03). Hip accelerometer counts decreased significantly (P= 0.01) after the switch to the KD, whereas there was no change in wrist accelerometer counts.Conclusion Switching to the KD increased EEDLW only on non-chamber days to an extent substantially greater than that originally reported. Increased physical activity as measured by accelerometry does not appear to account for this effect.Sources of Support Nutrition Science InitiativeClinical Trial Registry Data used in this study were derived from the clinical trial registered at http://www.clinicaltrials.gov as NCT01967563.AbbreviationsBDhigh-carbohydrate mixed macronutrient baseline dietEEenergy expenditureEEchambertotal daily energy expenditure measured in metabolic chambersEEDLWaverage energy expenditure measured by doubly labeled waterEEnonchamberaverage energy expenditure on days subjects were living on the ward outside metabolic chambers measured by doubly labeled waterKDlow-carbohydrate/high-fat ketogenic dietOSFOpen Science FrameworkSEEsleeping energy expenditure