RESUMEN

PURPOSE OF THE REVIEW: The use of bioelectrical impedance analysis (BIA) for monitoring body composition during the ketogenic diet has experienced a rapid surge. This scoping review aimed to assess the validity of procedures applying BIA in the ketogenic diet and to suggest best practices for optimizing its utilization. RECENT FINDINGS: We conducted a systematic scoping review of peer-reviewed literature involving BIA for assessing body composition in individuals adhering to a ketogenic diet. Searches of international databases yielded 1609 unique records, 72 of which met the inclusion criteria and were reviewed. Thirty-five studies used foot-to-hand technology, 34 used standing position technology, while 3 did not declare the technology used. Raw bioelectrical parameters were reported in 21 studies. A total of 196 body mass components were estimated, but predictive equations were reported in only four cases. Most research on BIA during ketogenic diets did not report the equations used for predicting body composition, making it impossible to assess the validity of BIA outputs. Furthermore, the exceedingly low percentage of studies reporting and analyzing raw data makes it challenging to replicate methodologies in future studies, highlighting that BIA is not being utilized to its full potential. There is a need for more precise technology and device characteristics descriptions, full report of raw bioelectrical data, and predictive equations utilized. Moreover, evaluating raw data through vectorial analysis is strongly recommended. Eventually, we suggest best practices to enhance BIA outcomes during ketogenic diets.

Asunto(s)

RESUMEN

Ketogenesis takes place in hepatocyte mitochondria where acetyl-CoA derived from fatty acid catabolism is converted to ketone bodies (KB), namely ß-hydroxybutyrate (ß-OHB), acetoacetate and acetone. KB represent important alternative energy sources under metabolic stress conditions. Ketogenic diets (KDs) are low-carbohydrate, fat-rich eating strategies which have been widely proposed as valid nutritional interventions in several metabolic disorders due to its substantial efficacy in weight loss achievement. Carbohydrate restriction during KD forces the use of FFA, which are subsequently transformed into KB in hepatocytes to provide energy, leading to a significant increase in ketone levels known as "nutritional ketosis". The recent discovery of KB as ligands of G protein-coupled receptors (GPCR) - cellular transducers implicated in a wide range of body functions - has aroused a great interest in understanding whether some of the clinical effects associated to KD consumption might be mediated by the ketone/GPCR axis. Specifically, anti-inflammatory effects associated to KD regimen are presumably due to GPR109A-mediated inhibition of NLRP3 inflammasome by ß-OHB, whilst lipid profile amelioration by KDs could be ascribed to the actions of acetoacetate via GPR43 and of ß-OHB via GPR109A on lipolysis. Thus, this review will focus on the effects of KD-induced nutritional ketosis potentially mediated by specific GPCRs in metabolic and endocrinological disorders. To discriminate the effects of ketone bodies per se, independently of weight loss, only studies comparing ketogenic vs isocaloric non-ketogenic diets will be considered as well as short-term tolerability and safety of KDs.

Asunto(s)

RESUMEN

Objective: to evaluate the lipid metabolism of patients with type 2 diabetes mellitus (T2DM) after very low-carbohydrate ketogenic (VLCK) diet treatment, so as to provide an evidence-based basis for better dietary management and comprehensive treatment of diabetic patients. Methods: PubMed, Cochrane Library, Embase, and Web of Science databases were searched for randomized controlled trial about VLCK diet on lipid metabolism of T2DM up to September 2021. The data were analyzed using the Stata 15.0; standardized mean difference (SMD) was used as effect size. Results: ten articles were included in this meta-analysis. There were no significant differences between the two groups in total cholesterol (SMD = -0.07, 95 % CI: -0.06-0.20, p > 0.05), HDL (SMD = 0.13, 95 % CI: -0.05-0.31, p > 0.05) and LDL (SMD = 0.07, 95 % CI: -0.06-0.20, p > 0.05) levels after treatment. No difference was found in total cholesterol, HDL, and LDL levels between the two groups after 3, 6, and 12 months of treatment (p > 0.05). Triglyceride levels decreased after VLCK diet compared with control (SMD = -0.49, 95 % CI: -0.82 to -0.17, p = 0.003). A marked reduction of triglyceride levels was identified after 3 months of VLCK diet treatment (SMD = -0.69, 95 % CI: -1.00 to -0.38), without significant difference after 6 and 12 months. Conclusion: T2DM patients who receive a VLCK diet to lower blood glucose are not associated with increased levels of total cholesterol and LDL, and decreased levels of HDL. Additionally, this diet can achieve a short-term reduction of triglyceride levels (AU)

Objetivo: evaluar el metabolismo lipídico de los pacientes con diabetes mellitus de tipo 2 (DMT2) tras el tratamiento con una dieta cetogénica muy baja en carbohidratos (VLCK), con el fin de proporcionar una base basada en la evidencia para un mejor manejo dietético y un tratamiento integral de los pacientes diabéticos. Métodos: se buscaron en las bases de datos PubMed, Cochrane Library, Embase y Web of Science ensayos controlados aleatorios sobre los efectos de la dieta VLCK en el metabolismo de los lípidos de la DMT2 hasta septiembre de 2021. Los datos se analizaron con el Stata 15.0. Se utilizó la diferencia de medias estandarizada (DME) como tamaño del efecto. Resultados: se incluyeron diez artículos en este metaanálisis. No hubo diferencias significativas entre los dos grupos en los niveles de colesterol total (DME = -0,07, IC del 95 %: -0,06-0,20, p > 0,05), HDL (DME = 0,13, IC del 95 %: -0,05-0,31, p > 0,05) y LDL (DME = 0,07, IC del 95 %: -0,06-0,20, p > 0,05) después del tratamiento. No se encontraron diferencias en los niveles de colesterol total, HDL y LDL entre los dos grupos después de 3, 6 y 12 meses de tratamiento (p > 0,05). Los niveles de triglicéridos disminuyeron después de la dieta VLCK en comparación con el control (DME = -0,49, IC del 95 %: -0,82 a -0,17, p = 0,003). Se identificó una marcada reducción de los niveles de triglicéridos después de 3 meses de tratamiento con la dieta VLCK (DME = -0,69, IC del 95 %: -1,00 a -0,38), sin diferencias significativas después de 6 y 12 meses. Conclusión: los pacientes con DMT2 que reciben una dieta VLCK para reducir la glucemia no se asocian a un aumento de los niveles de colesterol total y LDL, y a una disminución de los niveles de HDL. Además, esta dieta puede lograr una reducción a corto plazo de los niveles de triglicéridos (AU)

Asunto(s)

RESUMEN

A 38-year-old male with no history of cardiac disease presented with chest pain typical of acute coronary syndrome. He assumed very-low-carbohydrate ketogenic diet (VLC-KD) 4 weeks prior to admission but no other lifestyle change. Workup showed dynamic ST-T changes on electrocardiogram, significantly elevated troponins, ketonuria, and mild rhabdomyolysis. Transthoracic echocardiogram revealed mild inferior wall hypokinesia and cardiac catheterization showed normal coronaries; hence, the diagnosis of type II myocardial infarction (MI) was established. Although the pathogenesis remains unclear, this temporal association between VLC-KD and type 2 MI raised some concerns about VLC-KD's cardiovascular safety profile.

Asunto(s)

RESUMEN

Very low-carbohydrate ketogenic diets (VLCKDs) are an emerging nutritional treatment for severe obesity and are associated with a significant improvement in non-alcoholic fatty liver disease (NAFLD). Little is known about the effect of sex differences on weight loss induced by following a VLCKD. The aim of this study was to investigate the effects of sex differences on weight loss and NAFLD improvement in patients with severe obesity undergoing a VLCKD. Forty-two females and 28 males with severe obesity underwent a 25-day VLCKD. Anthropometric parameters, bioimpedentiometry, degree of liver steatosis measured by ultrasonography, liver function tests, and glucose homeostasis were measured before and after the VLCKD. Males experienced a significantly larger excess body weight loss (EBWL) and a greater reduction in γ-glutamyl transferase (γGT) than females. Dividing the female group by menopausal status, a significant difference between males and pre-menopausal females was found for both EBWL and γGT. No significant difference between groups was observed for improvement in the Edmonton stage or in the degree of steatosis. We conclude that the efficacy of following a VLCKD in severe obesity is affected by sex differences and, for females, by menopausal status. Males seem to experience larger benefits than females in terms of EBWL and NAFLD improvement. These differences are attenuated after menopause, probably because of changes in hormonal profile and body composition.

Asunto(s)