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
Abstract
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 being 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). To assess the role of physical activity in the response to the KD, we analyzed accelerometer data from 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 a questionable outlier, by 283 ± 116 kcal/d (P = 0.03). Hip accelerometer counts decreased…
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Evidence Hub reads this as a secondary / pooled analysis, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence.
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