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 A previously published pilot study assessed energy expenditure (EE) of participants with overweight and obesity 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 by what was considered a relatively small extent after the switch to the KD, whereas EE measured using doubly labeled water (EE DLW) increased to a greater degree after the response in the chambers had waned. Using a publicly available dataset, we examined the effect of housing conditions on the magnitude of the increase in EE DLW after the switch to the KD and the role of physical activity in that response. Methods The 14-day EE DLW measurement period included 4 days when subjects were confined to chambers instead of living in wards. To determine the effect on EE DLW only for the days subjects were living in the wards, we calculated non-chamber EE (EE nonchamber). To assess the role of physical activity in the response to the KD, we analyzed chamber and non-chamber accelerometer data for the BD and KD EE DLW measurement periods. Results In comparison with the increase in average 14-day EE DLW of 151 kcal/d ± 63 (P = 0.03) after the switch to the KD, EE nonchamber increased by 203 ± 89 kcal/d (P = 0.04) or 283 ± 116 kcal/ d (P = 0.03) depending on the analytical approach. Hip accelerometer counts decreased significantly (P = 0.01) after the switch to the KD, whereas wrist and ankle accelerometer counts did not change.

The Effect of Dietary Intake and Nutritional Status on Anthropometric Development and Systemic Inflammation: An Observational Study

“…However, the decrease in energy requirements was not necessarily observed in our study group due to obesity but rather due to the body weight. This result is opposite to Friedman IM et al [ 36 ]. Friedman IM et al reported lower basal metabolic rate and changes in body mass; this is why these differences are more related to body mass distribution, physical activity level and gender.…”

“…Food intake has both an energy and a nutritional component, starting from the role and the importance of each macronutrient. Even if there are important metabolic differences between carbohydrates, proteins and lipids, we cannot question the presence of one, the lack of another and thus the body weight control [ 36 ]. In our paper, 906.1 kcal were attributed to carbohydrate metabolism, equivalent to 54.06% of the energy demand.…”

A Low-Carbohydrate Ketogenic Diet and Treadmill Training Enhanced Fatty Acid Oxidation Capacity but Did Not Enhance Maximal Exercise Capacity in Mice

“…During LCKD feeding, the body enters a unique metabolic state that mimics the state of fasting. The exact mechanism through which an LCKD lowers weight is not completely understood, but possible mechanisms include: (1) appetite suppression [ 22 ]; (2) increased energy expenditure [ 23 ]; and (3) enhanced lipid metabolism and decreased triglyceride storage demand [ 19 ]. However, according to our results, LCKD mice consumed more calories, leaving (2) and (3) as possible underlying mechanisms.…”

A Low-Protein High-Fat Diet Leads to Loss of Body Weight and White Adipose Tissue Weight via Enhancing Energy Expenditure in Mice

“…It has been established that diets low in protein (3–8% energy as protein) often induce higher appetite [ 29 ]; thus, the food intake and corresponding energy intake in the LPHF groups were much higher than those in the HPHF groups ( Figure S1 ). Therefore, we hypothesized that the weight loss caused by the LPHF diet might be attributed to the increased energy expenditure instead of appetite suppression [ 30 , 31 ].…”