Effect of Carbohydrate-Restricted Diets and Intermittent Fasting on Obesity, Type 2 Diabetes Mellitus, and Hypertension Management: Consensus Statement of the Korean Society for the Study of Obesity, Korean Diabetes Association, and Korean Society of Hypertension

The effects of low-carbohydrate diet on glucose and lipid metabolism in overweight or obese patients with T2DM: a meta-analysis of randomized controlled trials

Background

The dual burden of Type 2 Diabetes Mellitus (T2DM) and obesity is a critical public health issue. Low-carbohydrate diets have emerged as a potential intervention, yet clinical evidence remains inconclusive.

Purpose

This meta-analysis assesses the impact of low-carbohydrate diets on metabolic profiles in overweight or obese T2DM patients, aiming to guide clinical practice.

Methods

A systematic review identified randomized clinical trials (RCTs) comparing low-carbohydrate diets to control diets in T2DM patients from PubMed, Embase, and the Cochrane Library databases up to April 2023.

Results

Seventeen RCTs, encompassing 1,197 participants, demonstrated that low-carbohydrate diets significantly improved HbA1c levels and fasting plasma glucose (mean difference [MD] = -0.36, 95% CI -0.44 to -0.29, p < 0.00001; MD = -10.71, 95% CI -14.39 to -7.03, p < 0.00001). They also reduced triglycerides and increased HDL cholesterol (MD = -19.91, 95% CI -28.83 to -10.99, p < 0.00001; MD = 2.49, 95% CI 1.07-3.91, p = 0.0006), without affecting LDL and total cholesterol. Weight loss, reduced BMI, lower diastolic blood pressure, and decreased waist circumference were additional benefits.

Conclusion

Low-carbohydrate diets may enhance glycemic control and lipid profiles in overweight or obese T2DM patients, warranting consideration in T2DM management. However, the variability in diet definitions and methodologies underscores the necessity for further research to standardize dietary guidelines and evaluate long-term effects.

A network meta-analysis of the comparative efficacy of different dietary approaches on glycaemic control and weight loss in patients with type 2 diabetes mellitus and overweight or obesity

Background: Despite considerable literature supporting the benefit of dietary interventions in individuals with type 2 diabetes mellitus (T2DM) and overweight/obesity, which diet works best is currently unknown. We conducted a systematic review and network meta-analysis (NMA) to evaluate the comparative effectiveness of different dietary approaches in overweight or obese adults with T2DM. Methods: We searched EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL) and PubMed up till July 2023 for controlled studies using different dietary approaches. Next, we updated the literature search to September 2024 but found no new relevant studies. Glycated hemoglobin A1c (HbA1c) levels and body weight were used as primary outcomes. For each outcome, a pooled effect was determined for each intervention compared with other interventions. Mean differences (MDs) and 95% confidence intervals (95% CIs) were computed. The surface under the cumulative ranking curve (SUCRA) was used for ranking the dietary approaches. Moreover, confidence was assessed using the CINeMA (confidence in network meta-analysis) framework. Results: Overall, 31 trials that compared eight diet interventions (Mediterranean, moderate-carbohydrate, low-carbohydrate, vegetarian, low-glycaemic index/load, low-fat, high-protein and control diets) and involved 3096 people were included. In terms of glycemic control, the Mediterranean diet yielded the best ranking (SUCRA: 88.15%), followed by the moderate-carbohydrate diet (SUCRA: 83.3%) and low-carbohydrate (LC) diet (SUCRA: 55.7%). In terms of anthropometric measurements, the LC diet (SUCRA: 74.6%) ranked first, followed by the moderate-carbohydrate diet (SUCRA: 68.7%) and vegetarian diet (SUCRA: 57%). These results also showed that the differences in almost all dietary patterns regarding anthropometric measurements were mostly small and often trivial. Conclusions: In summary, the Mediterranean diet was the most efficient dietary intervention for the improvement of glycaemic control, and the LC diet obtained the highest score for anthropometric measurements in individuals with T2DM and concurrent overweight/obesity.

Alzheimer's Disease, Obesity, and Type 2 Diabetes: Focus on Common Neuroglial Dysfunctions (Critical Review and New Data on Human Brain and Models)

BACKGROUND/OBJECTIVES

Obesity, type 2 diabetes (T2D), and Alzheimer's disease (AD) are pathologies that affect millions of people worldwide. They have no effective therapy and are difficult to prevent and control when they develop. It has been known for many years that these diseases have many pathogenic aspects in common. We highlight in this review that neuroglial cells (astroglia, oligodendroglia, and microglia) play a vital role in the origin, clinical-pathological development, and course of brain neurodegeneration. Moreover, we include the new results of a T2D-AD mouse model (APP+PS1 mice on a high-calorie diet) that we are investigating.

METHODS

Critical bibliographic revision and biochemical neuropathological study of neuroglia in a T2D-AD model.

RESULTS

T2D and AD are not only "connected" by producing complex pathologies in the same individual (obesity, T2D, and AD), but they also have many common pathogenic mechanisms. These include insulin resistance, hyperinsulinemia, hyperglycemia, oxidative stress, mitochondrial dysfunction, and inflammation (both peripheral and central-or neuroinflammation). Cognitive impairment and AD are the maximum exponents of brain neurodegeneration in these pathological processes. both due to the dysfunctions induced by metabolic changes in peripheral tissues and inadequate neurotoxic responses to changes in the brain. In this review, we first analyze the common pathogenic mechanisms of obesity, T2D, and AD (and/or cerebral vascular dementia) that induce transcendental changes and responses in neuroglia. The relationships between T2D and AD discussed mainly focus on neuroglial responses. Next, we present neuroglial changes within their neuropathological context in diverse scenarios: (a) aging involution and neurodegenerative disorders, (b) human obesity and diabetes and obesity/diabetes models, (c) human AD and in AD models, and (d) human AD-T2D and AD-T2D models. An important part of the data presented comes from our own studies on humans and experimental models over the past few years. In the T2D-AD section, we included the results of a T2D-AD mouse model (APP+PS1 mice on a high-calorie diet) that we investigated, which showed that neuroglial dysfunctions (astrocytosis and microgliosis) manifest before the appearance of amyloid neuropathology, and that the amyloid pathology is greater than that presented by mice fed a normal, non-high-caloric diet A broad review is finally included on pharmacological, cellular, genic, and non-pharmacological (especially diet and lifestyle) neuroglial-related treatments, as well as clinical trials in a comparative way between T2D and AD. These neuroglial treatments need to be included in the multimodal/integral treatments of T2D and AD to achieve greater therapeutic efficacy in many millions of patients.

CONCLUSIONS

Neuroglial alterations (especially in astroglia and microglia, cornerstones of neuroinflammation) are markedly defining brain neurodegeneration in T2D and A, although there are some not significant differences between each of the studied pathologies. Neuroglial therapies are a very important and p. promising tool that are being developed to prevent and/or treat brain dysfunction in T2D-AD. The need for further research in two very different directions is evident: (a) characterization of the phenotypic changes of astrocytes and microglial cells in each region of the brain and in each phase of development of each isolated and associated pathology (single-cell studies are mandatory) to better understand the pathologies and define new therapeutic targets; (b) studying new therapeutic avenues to normalize the function of neuroglial cells (preventing neurotoxic responses and/or reversing them) in these pathologies, as well as the phenotypic characteristics in each moment of the course and place of the neurodegenerative process.

Adherence to the nutritional recommendations according to diabetes status in Korean adults: a cross-sectional study

BACKGROUND

Nutritional therapy plays a crucial role in diabetes management. Assessing adherence to nutritional recommendations is critical for evaluating whether the current status of nutrition education is appropriate. This study aimed to evaluate adherence to nutritional recommendations according to diabetes status using data from the Korean National Health and Nutrition Examination Survey from 2016 to 2019.

METHODS

A total of 2,793 participants (55.4% male) were evaluated regarding their adherence to nutritional recommendations. The "aware" group comprised people who had been clinically diagnosed by a physician. The "treated" group comprised people receiving anti-diabetic medications. The "control" group comprised people who achieved an HbA1c level < 6.5%. The "educated" group comprised people who had received nutrition education or counseling at various locations.

RESULTS

Among the 1,918 individuals in the "aware" group, only 243 (8.7%) had received nutrition education. Adherence to nutritional recommendations was generally low, with people with diabetes showing slightly higher adherence to total energy intake (59.6% vs. 55.3%) and total sugar intake (88.0% vs. 84.5%) than people without diabetes. However, adherence to total carbohydrate intake was poor in both the treated and educated groups (34.3% and 26.0%, respectively) compared to the untreated and non-educated groups (44.4% and 36.0%, respectively).

CONCLUSIONS

These findings indicate inadequate nutritional management for people with diabetes in Korea. Nutrition education should be effectively strengthened to achieve nutritional goals.

Low-Carbohydrate Dietary Interventions for Metabolic Control in Individuals With Type 2 Diabetes Mellitus: An Overview of Systematic Reviews

CONTEXT

Dietary interventions providing different amounts of carbohydrates have been proposed as a means of achieving glycemic control and weight loss in type 2 diabetes mellitus (T2DM); however, the supporting evidence is heterogeneous, making this recommendation difficult to apply in nutritional clinical practice.

OBJECTIVE

The aim was to assess the quality of evidence from meta-analyses on low-carbohydrate (LC) dietary interventions for glycemic control, weight loss, and lipid profile in individuals with T2DM.

DATA SOURCES

The MEDLINE, Web of Science, and Scopus databases were searched until September 2023.

DATA EXTRACTION

A systematic review was conducted. Systematic reviews with meta-analysis of randomized clinical trials designed to assess glycated hemoglobin (HbA1c) reductions in individuals with T2DM were eligible. The AMSTAR-2 critical appraisal tool was used to evaluate the methodological aspects of all included studies. The GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach was used to assess the certainty of the evidence.

DATA ANALYSIS

The LC interventions were associated with a reduction in HbA1c (%) of -0.42 (-1.45 to -0.09; high certainty of evidence) without considering follow-up time; at up to 3 months of follow-up of -0.28 (-0.13 to -0.43); at up to 6 months of follow-up of -0.40 (-0.61 to -0.09); at 6 to 12 months of follow-up of -0.32 (-0.49 to 0.11); and at >12 months of follow-up time of -0.31 (-0.14 to -0.65) compared with control diets.

CONCLUSION

LC diets can help reduce HbA1c in individuals with T2DM in the short term (up to 3 months). However, dietary recommendations must always be individualized, as the studies reviewed herein analyzed different populations and used different definitions of what constitutes an LC diet.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO no. CRD42023404197.

Metabolic changes with intermittent fasting

BACKGROUND

The prevalence of obesity is rising globally and effective strategies to treat obesity are needed. Intermittent fasting, a dietary intervention for weight management, has received growing interest from the general public, as well as healthcare professionals, as a form of lifestyle intervention.

METHODS

We executed a rapid review using PUBMED database to identify systematic reviews that examined the impact of intermittent fasting on metabolic indices, published between 2011 and 2022.

RESULTS

Intermittent fasting leads to weight loss of a similar magnitude to continuous energy restriction. Most of the evidence shows that intermittent fasting leads to greater fat loss as measured by fat mass (kg) or body fat percentage compared to an ad libitum diet, but fat loss attained during intermittent fasting is not significantly different to continuous energy restriction, although recent evidence shows intermittent fasting to be superior. There is mixed evidence for the impact of intermittent fasting on insulin resistance, fasting glucose and lipid profile. Some studies focused on populations of Muslim people, which showed that Ramadan fasting may lead to weight loss and improvement of metabolic parameters during fasting, although the effects are reversed when fasting is finished.

CONCLUSIONS

Intermittent fasting is more effective than an ad libitum dietary intake, and equally or more effective as continuous energy restriction, for weight management. However, there is inconclusive evidence on whether intermittent fasting has a clinically beneficial effect on glucose and lipid metabolism.

The Value of Intermittent Fasting and Low Carbohydrate Diet in Prediabetic Patients for the Prevention of Cardiovascular Diseases

BACKGROUND

Prediabetic patients are at increased risk for cardiovascular diseases and the development of microvascular and macrovascular complications. Intermittent fasting (IF) and low-carbohydrate diet (LCD) are promising dietary plans.

OBJECTIVES

Our aims to analyze the benefits of IF combined with LCD on microvascular and macrovascular outcomes in prediabetic patients.

METHODS

The study included 485 prediabetic patients with no history of cardiovascular diseases divided into group I: (n = 240 patients) who underwent IF (16 h IF 3-4 days per week) combined with LCD (<130 g of carbohydrate per day), and group II: (n = 245 patients) with ad libitum calorie intake. The two groups were followed-up for two years for assessment of micro and macrovascular complications. A p-value < 0.05 was considered statistically significant.

RESULT

There was a significant reduction in body weight, body mass index, waist circumference, body fat percentage and glycated hemoglobin in group I. The incidence of progression from prediabetes to diabetes was significantly lower in group I (2.1% vs. 6.9% in group II, p = 0.010). In addition, a significant increase in the incidence of microvascular and macrovascular complications was observed in group II, including retinopathy, neuropathy and unstable angina. Multivariate regression analysis revealed that increased body weight, fasting glucose, glycated hemoglobin and low-density lipoprotein were independent risk factors impacting microvascular and macrovascular outcomes.

CONCLUSIONS

In prediabetic patients, IF, combined with LCD, was associated with lower progression to diabetes mellitus and lower incidence of microvascular and macrovascular complications.

Updated Meta-Analysis of Studies from 2011 to 2021 Comparing the Effectiveness of Intermittent Energy Restriction and Continuous Energy Restriction

Background

Despite the considerable number of trials and meta-analyses of studies on intermittent energy restriction (IER), it is not preferred to continuous energy restriction (CER) by the majority of obesity specialists. In this meta-analysis, we compare the effects of IER and CER on obesity using evidence from randomized controlled trials (RCTs).

Methods

A systematic electronic literature search was conducted to find RCTs published between January 1, 2011, and December 31, 2021 that directly compared IER and CER for an active weight loss period of at least 12 weeks and reported obesity indices or metabolic markers in adults with overweight or obesity. Finally, 16 RCTs from 25 articles with 1,438 participants were included.

Results

The attrition rates were 26.6% and 24.1% in the IER and CER groups, respectively, with no significant differences in changes in body weight, waist circumference, or body fat composition. CER changed blood glucose levels more than IER, but there was no significant difference in glycated hemoglobin levels. Systolic blood pressure was significantly lower in the CER group than the IER group, but diastolic blood pressure did not differ significantly between the groups. Changes in blood lipids did not differ significantly between the interventions. No differences between IER and CER were observed in the sensitivity analyses.

Conclusion

IER can be an alternative to CER because it induces comparable weight reduction and metabolic improvement. However, the effect of IER was not superior to that of CER, and its attrition rate was not lower than that of CER.

The Related Metabolic Diseases and Treatments of Obesity

Obesity is a chronic disease characterized by the abnormal or excessive accumulation of body fat, affecting more than 1 billion people worldwide. Obesity is commonly associated with other metabolic disorders, such as type 2 diabetes, non-alcoholic fatty liver disease, cardiovascular diseases, chronic kidney disease, and cancers. Factors such as a sedentary lifestyle, overnutrition, socioeconomic status, and other environmental and genetic conditions can cause obesity. Many molecules and signaling pathways are involved in the pathogenesis of obesity, such as nuclear factor (NF)-κB, Toll-like receptors (TLRs), adhesion molecules, G protein-coupled receptors (GPCRs), programmed cell death 1 (PD-1)/programmed death-ligand 1 (PD-L1), and sirtuin 1 (SIRT1). Commonly used strategies of obesity management and treatment include exercise and dietary change or restriction for the early stage of obesity, bariatric surgery for server obesity, and Food and Drug Administration (FDA)-approved medicines such as semaglutide and liraglutide that can be used as monotherapy or as a synergistic treatment. In addition, psychological management, especially for patients with obesity and distress, is a good option. Gut microbiota plays an important role in obesity and its comorbidities, and gut microbial reprogramming by fecal microbiota transplantation (FMT), probiotics, prebiotics, or synbiotics shows promising potential in obesity and metabolic syndrome. Many clinical trials are ongoing to evaluate the therapeutic effects of different treatments. Currently, prevention and early treatment of obesity are the best options to prevent its progression to many comorbidities.

Comprehensive Understanding for Application in Korean Patients with Type 2 Diabetes Mellitus of the Consensus Statement on Carbohydrate-Restricted Diets by Korean Diabetes Association, Korean Society for the Study of Obesity, and Korean Society of Hypertension

The Joint Committee of the Korean Diabetes Association, the Korean Society for the Study of Obesity, and the Korean Society of Hypertension announced a consensus statement on carbohydrate-restricted diets and intermittent fasting, representing an emerging and popular dietary pattern. In this statement, we recommend moderately-low-carbohydrate or low-carbohydrate diets, not a very-low-carbohydrate diet, for patients with type 2 diabetes mellitus. These diets can be considered a dietary regimen to improve glycemic control and reduce body weight in adults with type 2 diabetes mellitus. This review provides the detailed results of a meta-analysis and systematic literature review on the potential harms and benefits of carbohydrate-restricted diets in patients with diabetes. We expect that this review will help experts and patients by fostering an in-depth understanding and appropriate application of carbohydrate-restricted diets in the comprehensive management of diabetes.