Efficacy and safety of very low calorie ketogenic diet (VLCKD) in patients with overweight and obesity: A systematic review and meta-analysis

Hypovitaminosis D and the endocrine phenotype of COVID-19

BACKGROUND

Vitamin D and its deficiency have recently been suspected to be involved in increased susceptibility and negative outcomes of COVID-19. This assumption was based on the well known immunomodulatory actions of vitamin D and on the consistent finding of low levels of 25 hydroxyvitamin D (25OHD) in hospitalized patients with COVID-19. Moreover, several studies reported a correlation between 25OHD levels and different clinical outcomes of the disease.

AIM

Aim of the current review was to approach the topic of vitamin D and COVID-19 from a different perspective summarizing the data which led to the evidence of the existence of an endocrine phenotype of COVID-19.

CONCLUSIONS

This review analyzed in the light of the current knowledge the possibility that several endocrine manifestations of COVID-19 could be holistically interpreted in the context of an inadequate vitamin D status.

Effect of short-term ketogenic diet on end-tidal carbon dioxide

BACKGROUND & AIMS

Previous studies have shown that end-tidal carbon dioxide (EtCO₂) is lower with the presence of supraphysiological ketones as in the case of chronic ketogenic diet (KD) and diabetic ketoacidosis (DKA). This study aimed to determine changes in EtCO₂ upon short term KD.

METHODS

Healthy subjects were screened not to have conditions that exerts abnormal EtCO₂ nor contraindicated for KD. Subjects underwent seven days of KD while the EtCO2 and blood ketone (beta-hydroxybutyrate; β-OHB) parameters were sampled at day zero (t0) and seven (t7) of ketosis respectively. Statistically, the t-test and Pearson's coefficient were conducted to determine the changes and correlation of both parameters.

RESULTS

12 subjects completed the study. The mean score ± standard deviation (SD) for EtCO₂ were 35.08 ± 3.53 and 35.67 ± 3.31 mm Hg for t0 and t7 respectively. The mean score ±SD for β-OHB were 0.07 ± 0.08 and 0.87 ± 0.84 mmol/L for t0 and t7 respectively. There was no significant difference of EtCO₂ between the period of study (p > 0.05) but the β-OHB increased during t7 (p < 0.05). There was also no correlation between the parameters.

CONCLUSIONS

These findings suggest that EtCO₂ may not be utilized to determine short term nutritional ketosis.

Effect of Very-Low-Calorie Ketogenic Diet on Psoriasis Patients: A Nuclear Magnetic Resonance-Based Metabolomic Study

Psoriasis is an inflammatory disease of the epidermis based on an immunological mechanism involving Langerhans cells and T lymphocytes that produce pro-inflammatory cytokines. Genetic factors, environmental factors, and improper nutrition are considered triggers of the disease. Numerous studies have reported that in a high number of patients, psoriasis is associated with obesity. Excess adipose tissue, typical of obesity, causes a systemic inflammatory status coming from the inflammatory active adipose tissue; therefore, weight reduction is a strategy to fight this pro-inflammatory state. This study aimed to evaluate how a nutritional regimen based on a ketogenic diet influenced the clinical parameters, metabolic profile, and inflammatory state of psoriasis patients. To this end, 30 psoriasis patients were subjected to a ketogenic nutritional regimen and monitored for 4 weeks by evaluating the clinical data, biochemical and clinical parameters, NMR metabolomic profile, and IL-2, IL-1β, TNF-α, IFN-γ, and IL-4 concentrations before and after the nutritional regimen. Our data show that a low-calorie ketogenic diet can be considered a successful strategy and therapeutic option to gain an improvement in psoriasis-related dysmetabolism, with significant correction of the full metabolic and inflammatory status.

Macronutrients, microbiome and precision nutrition

PURPOSE OF REVIEW

Precision nutrition and personalized diets are gaining popularity in nutritional science and medicine. To fully appreciate their potential benefits, a deep understanding of both macronutrients and nutrient-microbe interactions is required.

RECENT FINDINGS

Microbiome science has reaffirmed the importance of dietary fiber in microbial and host health. Additional macronutrients, digestible carbohydrate, protein and fat also influence the composition and diversity of the microbiome and, therefore, microbial response to dietary intervention. Attention to macronutrient source, dose, microbial effect and metabolite production allows the development of more established links between diet and health.

SUMMARY

The degree to which human diets need to be personalized for optimal health is still uncertain but a one-size-fits-all diet seems unlikely. However, for personal or precision nutrition to fulfill its promise, greater attention to the details of nutrient-microbe interactions will be required.

Nutritional intervention strategies for the management of overweight and obesity in primary health care: A systematic review with meta-analysis

A systematic review with meta-analysis (MA) was conducted to synthesize the effectiveness of nutrition intervention strategies for managing overweight and obesity in the adult population attending primary health care. Relevant articles were searched in the PubMed, Embase, Web of Science, Cochrane and LILACS databases from inception to January 2020. Seventy studies were identified: 45 randomized controlled trials (RCTs) and 25 uncontrolled before-after studies (UBAs). The MA of nutritional intervention revealed a reduced average estimate of the effect on weight in RCTs (weighted mean differences [WMD] = -1.80 kg, 95% confidence interval [CI], -2.40 to -1.19), BMI (WMD = -0.80 kg/m² , 95% CI, -1.11 to -0.49), and WC (WMD = -2.28 cm, 95% CI, -3.06 to -1.49); and for UBAs showed reductions in weight (WMD = -4.17 kg; 95% CI, -5.18 to -1.70), BMI (WMD = -1.26 kg/m² ; 95% CI, -1.81 to -0.72) and (WMD = -2.90 cm; 95%CI, -4.21 to -1.59). There was no association between treatment effect and follow-up for both designs. Nutritional interventions alone yielded a higher but nonsignificant average reduction on weight when compared with combined components intervention. Interventions delivered through individual or group sessions showed a similar positive effect on weight decrease. The dietary prescription approach yielded a greater effect on weight loss than did the behavioural approaches but only in UBA studies.

Very-Low-Calorie Ketogenic Diet as a Safe and Valuable Tool for Long-Term Glycemic Management in Patients with Obesity and Type 2 Diabetes

Obesity-related type 2 diabetes represents one of the most difficult challenges for the healthcare system. This retrospective study aims to determine the efficacy, safety and durability of a very-low-calorie ketogenic diet (VLCKD), compared to a standard low-calorie diet (LCD) on weight-loss, glycemic management, eating behavior and quality of life in patients with type 2 diabetes (T2DM) and obesity. Thirty patients with obesity and T2DM, aged between 35 and 75 years, who met the inclusion criteria and accepted to adhere to a VLCKD or a LCD nutritional program, were consecutively selected from our electronic database. Fifteen patients followed a structured VLCKD protocol, fifteen followed a classical LCD. At the beginning of the nutritional protocol, all patients were asked to stop any antidiabetic medications, with the exception of metformin. Data were collected at baseline and after 3 (T1) and 12 (T2) months. At T1 and T2, BMI was significantly reduced in the VLCKD group (p < 0.001), whereas it remained substantially unchanged in the LCD group. HbA1c was significantly reduced in the VLCKD group (p = 0.002), whereas a slight, although not significant, decrease was observed in the LCD group. Quality of life and eating behavior scores were improved in the VLCKD group, whereas no significant changes were reported in the LCD group, both at T1 and T2. At the end of the study, in the VLCKD group 26.6% of patients had stopped all antidiabetic medications, and 73.3% were taking only metformin, whereas 46.6% of LCD patients had to increase antidiabetic medications. The study confirms a valuable therapeutic effect of VLCKD in the long-term management of obesity and T2DM and its potential contribution to remission of the disease.

Nutritional Approach Targeting Gut Microbiota in NAFLD-To Date

Non-alcoholic fatty liver disease (NAFLD) is a significant clinical and epidemiological problem that affects around 25% of the adult global population. A large body of clinical evidence highlights that NAFLD is associated with increased liver-related morbidity and mortality and an increased risk of cardiovascular disease, extrahepatic cancers, type 2 diabetes, and chronic kidney disease. Recently, a series of studies revealed the pivotal role of gut microbiota (GM) dysbiosis in NAFLD's pathogenesis. The GM plays an essential role in different metabolic pathways, including the fermentation of diet polysaccharides, energy harvest, choline regulation, and bile acid metabolism. One of the most critical factors in GM stabilization is the diet; therefore, nutritional therapyappearsto be a promising tool in NAFLD therapy. This paper aims to review the current knowledge regardingthe nutritional approach and its implications with GM and NAFLD treatment. We discuss the positive impact of probiotics, prebiotics, and symbiotics in a reverse dysbiosis state in NAFLD and show the potential beneficial effects of bioactive substances from the diet. The full description of the mechanism of action and comprehensive examination of the impact of nutritional interventions on GM modulation may, in the future, be a simple but essential tool supporting NAFLD therapy.

The Effect of Antioxidant and Anti-Inflammatory Capacity of Diet on Psoriasis and Psoriatic Arthritis Phenotype: Nutrition as Therapeutic Tool?

Chronic inflammation and increased oxidative stress are contributing factors to many non-communicable diseases. A growing body of evidence indicates that dietary nutrients can activate the immune system and may lead to the overproduction of pro-inflammatory cytokines. Fatty acids as macronutrients are key players for immunomodulation, with n-3 polyunsaturated fatty acids having the most beneficial effect, while polyphenols and carotenoids seem to be the most promising antioxidants. Psoriasis is a chronic, immune-mediated inflammatory disease with multifactorial etiology. Obesity is a major risk factor for psoriasis, which leads to worse clinical outcomes. Weight loss interventions and, generally, dietary regimens such as gluten-free and Mediterranean diet or supplement use may potentially improve psoriasis’ natural course and response to therapy. However, data about more sophisticated nutritional patterns, such as ketogenic, very low-carb or specific macro- and micro-nutrient substitution, are scarce. This review aims to present the effect of strictly structured dietary nutrients, that are known to affect glucose/lipid metabolism and insulin responses, on chronic inflammation and immunity, and to discuss the utility of nutritional regimens as possible therapeutic tools for psoriasis and psoriatic arthritis.

The effect of ketogenic diet on body composition and anthropometric measures: A systematic review and meta-analysis of randomized controlled trials

This study aimed to summarize earlier randomized controlled trials on the effects of ketogenic diet (KD) on body composition and anthropometric measures. Four databases were searched from inception to May 2020 using relevant keywords. All clinical trials investigating the effects of KD on body weight (BW), body mass index (BMI), waist circumference (WC), fat mass (FM), fat-free mass (FFM), lean body mass (LBM), visceral adipose tissue (VAT) and percentage body fat (PBF) in adults were included. Overall, 18 trials were included in the review. Pooled effect sizes revealed a significant effect of KD on BW (weighted mean differences [WMD]: -2.87 kg, 95% confidence interval [CI]: -3.84 to -1.89), BMI (WMD: -1.44 kg/m2, 95% CI: -2.07, -0.81), FM (WMD: -1.40 kg, 95% CI: -2.50, -0.30), FFM (WMD: -0.81 kg, 95% CI: -1.32, -0.30), LBM (WMD: -0.63 kg, 95% CI: -1.21, -0.06), WC (WMD: -3.23 cm, 95% CI: -4.38, -2.09), VAT (WMD: -28.91 g, 95% CI: -50.57, -7.24) and PBF (WMD: -2.81 kg, 95% CI: -3.82, -1.80), respectively. Taken together, the data suggest that KD has beneficial effects on BW, BMI, FM, FFM, LBM, WC, VAT, and PBF. However, the effectiveness of the long term effect of this dietary pattern is unclear.

Dietary interventions for obesity: clinical and mechanistic findings

Dietary modification is central to obesity treatment. Weight loss diets are available that include various permutations of energy restriction, macronutrients, foods, and dietary intake patterns. Caloric restriction is the common pathway for weight reduction, but different diets may induce weight loss by varied additional mechanisms, including by facilitating dietary adherence. This narrative Review of meta-analyses and select clinical trials found that lower-calorie diets, compared with higher-calorie regimens, reliably induced larger short-term (<6 months) weight losses, with deterioration of this benefit over the long term (>12 months). Few significant long-term differences in weight loss were observed for diets of varying macronutrient composition, although some regimens were found to have short-term advantages (e.g., low carbohydrate versus low fat). Progress in improving dietary adherence, which is critical to both short- and long-term weight loss, could result from greater efforts to identify behavioral and metabolic phenotypes among dieters.

Could ketogenic diet "starve" cancer? Emerging evidence

Cancer cells (CCs) predominantly use aerobic glycolysis (Warburg effect) for their metabolism. This important characteristic of CCs represents a potential metabolic pathway to be targeted in the context of tumor treatment. Being this mechanism related to nutrient oxidation, dietary manipulation has been hypothesized as an important strategy during tumor treatment. Ketogenic diet (KD) is a dietary pattern characterized by high fat intake, moderate-to-low protein consumption, and very-low-carbohydrate intake (<50 g), which in cancer setting may target CCs metabolism, potentially influencing both tumor treatment and prognosis. Several mechanisms, far beyond the originally proposed inhibition of glucose/insulin signaling, can underpin the effectiveness of KD in cancer management, ranging from oxidative stress, mitochondrial metabolism, and inflammation. The role of a qualified Nutritionist is essential to reduce and manage the short and long-term complications of this dietary therapy, which must be personalized to the individual patient for the planning of tailored KD protocol in cancer patients. In the present review, we summarize the proposed antitumor mechanisms of KD, the application of KD in cancer patients with obesity and cachexia, and the preclinical and clinical evidence on KD therapy in cancer.

Ketotherapy as an epigenetic modifier in cancer

Epigenetic alterations in cancer play a variety of roles. Aberrant DNA methylation, as one of the epigenetic mechanisms, has been widely studied in both tumor and liquid biopsies and provide a useful bench mark for treatment response in cancer. Recently, several studies have reported an association between the type of diet and epigenetic modifications. Whereby there is a growing interest in finding the "anti-cancer diet formula", if such a thing exists. In this sense, ketogenic diets (KD) have reported potentially beneficial effects, which were able to prevent malignancies and decrease tumor growth. Some studies have even shown increased survival in cancer patients, reduced side effects of cytotoxic treatments, and intensified efficacy of cancer therapies. Although the biological mechanisms of KD are not well understood, it has been reported that KD may affect DNA methylation by modulating the expression of crucial genes involved in tumor survival and proliferation. However, there are many considerations to take into account to use ketotherapy in cancer, such as epigenetic mark, type of cancer, immunological and metabolic state or microbiota profile. In this review, we argue about ketotherapy as a potential strategy to consider as coadjuvant of cancer therapy. We will focus on mainly epigenetic mechanisms and dietary approach that could be included in the current clinical practice guidelines.

Effect of the ketogenic diet on glycemic control, insulin resistance, and lipid metabolism in patients with T2DM: a systematic review and meta-analysis

Background

At present, the beneficial effect of the ketogenic diet (KD) on weight loss in obese patients is generally recognized. However, a systematic research on the role of KD in the improvement of glycemic and lipid metabolism of patients with diabetes is still found scarce.

Methods

This meta-study employed the meta-analysis model of random effects or of fixed effects to analyze the average difference before and after KD and the corresponding 95% CI, thereby evaluating the effect of KD on T2DM.

Results

After KD intervention, in terms of glycemic control, the level of fasting blood glucose decreased by 1.29 mmol/L (95% CI: −1.78 to −0.79) on average, and glycated hemoglobin A1c by 1.07 (95% CI: −1.37 to −0.78). As for lipid metabolism, triglyceride was decreased by 0.72 (95% CI: −1.01 to −0.43) on average, total cholesterol by 0.33 (95% CI: −0.66 to −0.01), and low-density lipoprotein by 0.05 (95% CI: −0.25 to −0.15); yet, high-density lipoprotein increased by 0.14 (95% CI: 0.03−0.25). In addition, patients’ weight decreased by 8.66 (95% CI: −11.40 to −5.92), waist circumference by 9.17 (95% CI: −10.67 to −7.66), and BMI by 3.13 (95% CI: −3.31 to −2.95).

Conclusion

KD not only has a therapeutic effect on glycemic and lipid control among patients with T2DM but also significantly contributes to their weight loss.

A Randomized, Controlled Trial Comparing the Impact of a Low-Calorie Ketogenic vs a Standard Low-Calorie Diet on Fat-Free Mass in Patients Receiving an Elipse™ Intragastric Balloon Treatment

Background

The Elipse™ intragastric balloon (EIGB) is a new swallowable balloon for weight loss (WL). Preserving metabolically active fat-free mass (FFM) and resting metabolic rate (RMR) during WL are crucial to maximize fat mass (FM) loss. After EIGB placement, a standard low-calorie diet (LCD) is generally prescribed. A low-calorie ketogenic diet (LCKD) has proven to be safe and effective in reducing FM while preserving FFM and RMR.

Objective

To prospectively compare the effects on WL, FM, FFM, and RMR in two groups of patients who were randomized to two different diets: LCKD and a standard LCD after EIGB placement.

Methods

WL, FM, FFM, and RMR were measured before EIGB and at 4 months in 48 patients who received either a LCKD (n = 24) or a standard LCD (n = 24). Compliance in following the prescribed diet was determined with food frequency questionnaires in all patients. The impact of LCKD and LCD on renal function was also evaluated.

Results

The LCKD group showed a significantly lower decrease in FFM and RMR when compared with the LCD group (3.55 vs 14.3%, p < 0.001; 9.79 vs 11.4%, p < 0.001, respectively). FM decreased more significantly with LCKD compared to LCD (41.6 vs 33.1%, p = 0.0606). Compliance in following the prescribed diets, without negative impact on renal function, was found.

Conclusion

Based on our findings, despite the small sample size, we were able to support the hypothesis that LCKD is associated with an increased FM loss while reducing the FFM loss and the RMR, without interfering with renal function after EIGB.

From Fad to Fact: Evaluating the Impact of Emerging Diets on the Prevention of Cardiovascular Disease

Cardiovascular disease remains one of the most prevalent and preventable chronic conditions worldwide. Diet modification is the foundation of cardiovascular disease prevention. Several dietary approaches have emerged to promote better cardiovascular health. The rapid dissemination of anecdotal and observational data through the internet and social media has caused confusion amongst providers and patients. The aim of this comprehensive review is to present objective insights into 2 of today's most popular fad diets: ketogenic diet and intermittent fasting. We will evaluate the performance of these diets based on their impact on cardiovascular risk factors.

Scientific evidence underlying contraindications to the ketogenic diet: An update

First identified as a feasible treatment for intractable epilepsy, the ketogenic diet (KD) has recently gained popularity thanks to growing evidence on applications such as weight loss, most importantly, but also NAFLD, cancer, neurologic conditions and chronic pain. As with any treatment, whether pharmacologic or not, the KD might not be an appropriate intervention for every individual, and a number of contraindications have been proposed, now deeply rooted into clinical practice, excluding de facto many patients that could benefit from its use. However, many of these concerns were expressed due to the absence of clinical studies conducted on fragile populations, and an assessment of lately emerged evidence relative to KD safety is currently lacking and much needed. We herein provide a critical revision of the literature behind each safety alert, in order to guide through the treatment options in the case of subjects with an indication to the KD and a borderline safe situation. Based on available evidence, the possible use of this diet as a therapeutic intervention should be assessed on a patient-to-patient basis by adequately skilled medical doctors, keeping in mind current recommendations, but reading them through the knowledge of the current state of the art.

Effectiveness of a Very Low Calorie Ketogenic Diet on Testicular Function in Overweight/Obese Men

Background: Obesity has become an increasingly worrisome reality. A very-low-calorie ketogenic diet (VLCKD) represents a promising option by which to achieve significant weight loss. This study sought to evaluate the effectiveness of VLCKD on metabolic parameters and hormonal profiles of obese male patients. Methods: We enrolled 40 overweight/obese men who consumed VLCKD for at least eight weeks. Body weight, waist circumference, fasting glucose, insulin, total cholesterol, high-density lipoprotein, triglycerides, creatinine, uric acid, aspartate aminotransferase, alanine aminotransferase, vitamin D, luteinizing hormone (LH), total testosterone (TT), and prostate-specific antigen (PSA) were calculated before and after VLCKD consumption. We additionally determined the homeostasis model assessment index and low-density lipoprotein (LDL) values. Results: After VLCKD (13.5 ± 0.83 weeks), the mean body weight loss was 21.05 ± 1.44 kg; the glucose homeostasis and lipid profile were improved significantly; serum vitamin D, LH, and TT levels were increased and the PSA levels were decreased significantly as compared with pretreatment values. These results are of interest since obesity can lead to hypogonadism and in turn, testosterone deficiency is associated with impaired glucose homeostasis, metabolic syndrome, and diabetes mellitus. Moreover, a close relationship between obesity, insulin resistance, and/or hyperinsulinemia and increased prostate volume has been reported, with a consequent greater risk of developing lower urinary tract symptoms. Conclusions: VLCKD is an effective tool against obesity and could be a noninvasive, rapid, and valid means to treat obese patients with metabolic hypogonadism and lower urinary tract symptoms.

Very low-calorie ketogenic diet (VLCKD) in patients with psoriasis and obesity: an update for dermatologists and nutritionists

Psoriasis is a chronic skin immune-mediated disease with systemic pro-inflammatory activation; both genetic and lifestyles factors contribute to its pathogenesis and severity. In this context, nutrition plays a significant role, per se, in psoriasis' pathogenesis. Obesity is another important risk factor for psoriasis, and weight reduction may improve psoriasis' clinical severity. The excess body weight, particularly visceral fat mass, can affect both drug's pharmacokinetics and pharmacodynamics. Therefore, psoriasis and obesity share a certain degree of synergy, and the chronic inflammatory state represents the basis of this vicious cycle. Evidence reported that nutrition has different impact on the clinical severity of psoriasis, though some specific diets have been more investigated in clinical studies compared to others. Diets with systemic anti-inflammatory properties seem to have a higher effect on improving the clinical severity of psoriasis. Of interest, very-low-calorie ketogenic diet (VLCKD), through the production of ketone bodies, has been associated with both a significant reduction of body weight and inflammatory state. VLCKD leading to both weight loss and reduction of systemic inflammation may decrease the exacerbation of the clinical manifestations or even it may block the trigger of psoriatic disease. This dietary pattern could represent a potential first-line treatment in psoriatic patients with obesity. The review aims to summarize the current evidence regarding VLCKD and psoriasis with specific reference to antioxidant and anti-inflammatory effects of this dietary pattern.

Very Low-Carbohydrate Ketogenic Diet for the Treatment of Severe Obesity and Associated Non-Alcoholic Fatty Liver Disease: The Role of Sex Differences

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.

Very low calorie ketogenic diets in overweight and obesity treatment: Effects on anthropometric parameters, body composition, satiety, lipid profile and microbiota

According to the World Health Organization (WHO) the prevalence of obesity tripled worldwide since 1975. Obesity prevention and treatment is based upon lifestyle changes involving eating habits, physical activity and behaviour therapy. Various dietary patterns have been used as nutritional strategies and, in recent years, interest has been shown in very low calorie ketogenic diets (VLCKD) that provide less than 800 calories (kcal), no more than 20-50 g/day of carbohydrates and 0.8-1.5 g/kg ideal body weight of protein. We conducted a literature review of all clinical trials published between January 2014-November 2019 on people with obesity (PWO) that evaluated VLCKD effects on anthropometric parameters, body composition, satiety, lipid profile and microbiota. Findings from literature showed that VLCKD could be useful to ameliorate the quality of life and sleep of PWO. It leads to a rapid weight loss and results in improvements in body mass index (BMI = kg/m²), waist circumference and fat mass reduction preserving lean body mass and resting metabolic rate. This eating pattern reduced the desire to eat and increased satiety. Little is known regarding the effects of VLCKD on the microbiota of PWO for which it is important to conduct further studies.

Ketogenic diets as treatment of obesity and type 2 diabetes mellitus

During the last decades, several interventions for the management of overweight and obesity have been proposed. Among diets, the first studies focused on the effect of water only and total fasting diets with or without proteins. Unfortunately, they were found to be associated with adverse events which lead to the abandon of these strategies. Interestingly, despite the radical approach, total fasting was effective and generally well tolerated. A strict connection between protein-calorie malnutrition and increased in morbidity and mortality in hospitalized patients was found at that time. Then, the seminal works of Blackburn and his collaborators lead to the introduction of the protein-sparing modified fast. Encouraged by the early results using this intervention, diets evolved to the current very-low-calorie ketogenic diets (VLCKD). In the present review, results of studies on the VLCKDs are presented and discussed, with a particular reference to the protocolled VLCKD. Also, a recent proposal on the nomenclature on the ketogenic diets is reported. Available evidence suggests VLCKDs to be effective in achieving a rapid and significant weight loss by means of an easily reversible intervention which could be repeated, if needed. Muscle mass and strength are preserved, resting metabolic rate is not impaired, hunger, appetite and mood are not worsened. Symptoms and abnormal laboratory findings can be there, but they have generally been reported as of mild intensity and transient. Preliminary studies suggest VLCKDs to be a potential game-changer in the management of type 2 diabetes too. Therefore, VLCKDs should be considered as an excellent initial step in properly selected and motivated patients with obesity or type 2 diabetes, to be delivered as a part of a multicomponent strategy and under strict medical supervision.

MicroRNA-21-Enriched Exosomes as Epigenetic Regulators in Melanomagenesis and Melanoma Progression: The Impact of Western Lifestyle Factors

DNA mutation-induced activation of RAS-BRAF-MEK-ERK signaling associated with intermittent or chronic ultraviolet (UV) irradiation cannot exclusively explain the excessive increase of malignant melanoma (MM) incidence since the 1950s. Malignant conversion of a melanocyte to an MM cell and metastatic MM is associated with a steady increase in microRNA-21 (miR-21). At the epigenetic level, miR-21 inhibits key tumor suppressors of the RAS-BRAF signaling pathway enhancing proliferation and MM progression. Increased MM cell levels of miR-21 either result from endogenous upregulation of melanocytic miR-21 expression or by uptake of miR-21-enriched exogenous exosomes. Based on epidemiological data and translational evidence, this review provides deeper insights into environmentally and metabolically induced exosomal miR-21 trafficking beyond UV-irradiation in melanomagenesis and MM progression. Sources of miR-21-enriched exosomes include UV-irradiated keratinocytes, adipocyte-derived exosomes in obesity, airway epithelium-derived exosomes generated by smoking and pollution, diet-related exosomes and inflammation-induced exosomes, which may synergistically increase the exosomal miR-21 burden of the melanocyte, the transformed MM cell and its tumor environment. Several therapeutic agents that suppress MM cell growth and proliferation attenuate miR-21 expression. These include miR-21 antagonists, metformin, kinase inhibitors, beta-blockers, vitamin D, and plant-derived bioactive compounds, which may represent new options for the prevention and treatment of MM.

Short-Term Physiological Effects of a Very Low-Calorie Ketogenic Diet: Effects on Adiponectin Levels and Inflammatory States

Adipose tissue is a multifunctional organ involved in many physiological and metabolic processes through the production of adipokines and, in particular, adiponectin. Caloric restriction is one of the most important strategies against obesity today. The very low-calorie ketogenic diet (VLCKD) represents a type of caloric restriction with very or extremely low daily food energy consumption. This study aimed to investigate the physiological effects of a VLCKD on anthropometric and biochemical parameters such as adiponectin levels, as well as analyzing oligomeric profiles and cytokine serum levels in obese subjects before and after a VLCKD. Twenty obese subjects were enrolled. At baseline and after eight weeks of intervention, anthropometric and biochemical parameters, such as adiponectin levels, were recorded. Our findings showed a significant change in the anthropometric and biochemical parameters of these obese subjects before and after a VLCKD. We found a negative correlation between adiponectin and lipid profile, visceral adipose tissue (VAT), C-reactive protein (CRP), and pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), which confirmed the important involvement of adiponectin in metabolic and inflammatory diseases. We demonstrated the beneficial short-term effects of a VLCKD not only in the treatment of obesity but also in the establishment of obesity-correlated diseases.

Modulation of Cellular Biochemistry, Epigenetics and Metabolomics by Ketone Bodies. Implications of the Ketogenic Diet in the Physiology of the Organism and Pathological States

Ketone bodies (KBs), comprising β-hydroxybutyrate, acetoacetate and acetone, are a set of fuel molecules serving as an alternative energy source to glucose. KBs are mainly produced by the liver from fatty acids during periods of fasting, and prolonged or intense physical activity. In diabetes, mainly type-1, ketoacidosis is the pathological response to glucose malabsorption. Endogenous production of ketone bodies is promoted by consumption of a ketogenic diet (KD), a diet virtually devoid of carbohydrates. Despite its recently widespread use, the systemic impact of KD is only partially understood, and ranges from physiologically beneficial outcomes in particular circumstances to potentially harmful effects. Here, we firstly review ketone body metabolism and molecular signaling, to then link the understanding of ketone bodies’ biochemistry to controversies regarding their putative or proven medical benefits. We overview the physiological consequences of ketone bodies’ consumption, focusing on (i) KB-induced histone post-translational modifications, particularly β-hydroxybutyrylation and acetylation, which appears to be the core epigenetic mechanisms of activity of β-hydroxybutyrate to modulate inflammation; (ii) inflammatory responses to a KD; (iii) proven benefits of the KD in the context of neuronal disease and cancer; and (iv) consequences of the KD’s application on cardiovascular health and on physical performance.

Confusion in the nomenclature of ketogenic diets blurs evidence

Ketogenic diets have been proposed as a non-pharmacological strategy for the management of several chronic conditions. Their efficacy and safety have been evaluated in the field of neurology, oncology and endocrinology for disorders including cancer, dementia, drug-resistant epilepsy, migraines, obesity, polycystic ovary syndrome and type 2 diabetes mellitus. The nutritional requirements of these subjects are expected to differ significantly. Indeed, although all ketogenic diets restrict carbohydrates, each intervention is characterized by a specific daily calorie intake, macronutrient composition and duration. However, the adopted nomenclature was often unclear to the general reader; also, the same abbreviations for different protocols were used. This possibly resulted in mistakes in the interpretation of the available evidence and limited the impact of studies on the topic in the clinical practice. Adopting a clear and consistent vocabulary is key in any context. Here, we present a practical and clinically-based proposal for the classification and abbreviation of ketogenic diets.

Very Low-Calorie Ketogenic Diet: A Safe and Effective Tool for Weight Loss in Patients With Obesity and Mild Kidney Failure

Very low-calorie ketogenic diets (VLCKD) are an effective and increasingly used tool for weight loss. Traditionally considered high protein, ketogenic diets are often looked at with concern by clinicians due to the potential harm they pose to kidney function. We herein evaluated the efficacy and safety of a VLCKD in patients with obesity and mild kidney failure. A prospective observational real-life study was conducted on ninety-two patients following a VLCKD for approximately 3 months. Thirty-eight had mild kidney failure and fifty-four had no renal condition and were therefore designated as control. Anthropometric parameters, bioelectrical impedance and biochemistry data were collected before and at the end of the dietary intervention. The average weight loss was nearly 20% of initial weight, with a significant reduction in fat mass. We report an improvement of metabolic parameters and no clinically relevant variation regarding liver and kidney function. Upon stratification based on kidney function, no differences in the efficacy and safety outcomes were found. Interestingly, 27.7% of patients with mild renal failure reported normalization of glomerular filtrate after dietary intervention. We conclude that, when conducted under the supervision of healthcare professionals, a VLCKD is an effective and safe treatment for weight loss in patients with obesity, including those affected by mild kidney failure.

Identification of Reactive Hypoglycemia with Different Basic BMI and Its Causes by Prolonged Oral Glucose Tolerance Test

PURPOSE

To identify the population susceptible to reactive hypoglycemia and explain the possible reasons for their susceptibility.

METHODS

Ninety-four patients were divided into normal weight, overweight and obese groups before a 75-gram prolonged oral glucose tolerance test (POGTT). The incidence of reactive hypoglycemia (blood glucose ≤3.1 mmol/L or 55 mg/dL at points of 0-4 hours) was compared among three groups, and blood glucose and insulin levels were monitored simultaneously from 0 - 4 hours to assess the level of insulin resistance and insulin sensitivity. Furthermore, the degree of insulin resistance among three groups and within each subgroup (whether hypoglycemia events occurred) was compared.

RESULTS

Among the three groups, the incidence of hypoglycemia was significantly different at 3 (P=0.033) and 4 hours (P=0.020). At 4 hours, the incidence of reactive hypoglycemia in the obese group was approximately 3 times that in the normal weight group. The insulin level in obese group at 4 hours was nearly 4 times higher than that in normal group, and the same result also exists in the same subgroup of different groups. In addition, the hypoglycemia subgroup of obese group had higher insulin level than non-hypoglycemia (P=0.000). The homeostasis model assessment of insulin resistance index increased with increasing BMI among the three groups (P=0.000), while the Matsuda index decreased (P=0.000). The comparison of the homeostasis model assessment of insulin resistance index between subgroups in each group showed that the P values were 0.021, 0.038 and 0.085, successively, and the P values for the Matsuda index were 0.019, 0.013 and 0.119, respectively.

CONCLUSION

Obese people has higher rate of reactive hypoglycemia than other groups in POGTT, in which insulin resistance may play an important role. But patients who are evaluated for reactive hypoglycemia need to be observed for at least 3 or 4 hours.