Low glycaemic index diets as an intervention for obesity: a systematic review and meta-analysis

Effect of a Low-Glycemic Index Nutritional Intervention on Body Weight and Selected Cardiometabolic Parameters in Children and Adolescents with Excess Body Weight and Dyslipidemia

Excess body weight in pediatric patients and the resulting dyslipidemia, if left untreated, are a serious risk factor for cardiovascular disease in young adults. Despite this, there is still no effective and validated nutritional strategy for the treatment of overweight/obesity and comorbid dyslipidemia in children and adolescents. A low-glycemic index (LGI) diet may be recommended, but evidence for its effectiveness in the pediatric population is limited. The aim of this study was to evaluate the effectiveness of nutritional intervention in children and adolescents with excess body weight and dyslipidemia. The study was conducted in patients aged 8-16 with overweight or obesity and lipid disorders (n = 64), of which 40 participants who completed the entire 8-week study were included in the analysis. Patients were randomly selected and allocated to one of the two dietary groups: the LGI diet or the standard therapy (ST) diet. Both diets were based on the principal recommendation of Cardiovascular Health Integrated Lifestyle Diet-2 (CHILD-2). This study showed that both LGI and ST diets were equally beneficial in reducing body weight, body fat, blood pressure, total cholesterol (TC), and triglyceride (TG) levels. The LGI diet, compared to the ST diet, was less effective in reducing blood TG levels but more effective in reducing diastolic blood pressure (DBP). Therefore, the choice of the type of diet in the treatment of children and adolescents with excess body weight and dyslipidemia may be individual. However, it should be based on the recommendation of CHILD-2. Further long-term, larger-scale studies are needed.

Effects of Dietary Carbohydrate Concentration and Glycemic Index on Blood Glucose Variability and Free Fatty Acids in Individuals with Type 1 Diabetes

Monitoring glycemic control status is the cornerstone of diabetes management. This study aimed to reveal whether moderate-carbohydrate (CHO) diets increase the risk of free fatty acid (FFA) levels, and it presents the short-term effects of four different diet models on blood sugar, glycemic variability (GV), and FFA levels. This crossover study included 17 patients with type 1 diabetes mellitus to identify the effects of four diets with different CHO contents and glycemic index (GI) on GV and plasma FFA levels. Diet 1 (D1) contained 40% CHO with a low GI, diet 2 (D2) contained 40% CHO with a high GI, diet 3 (D3) contained 60% CHO with a low GI, and diet 4 (D4) contained 60% CHO with a high GI. Interventions were performed with sensor monitoring in four-day periods and completed in four weeks. No statistical difference was observed among the groups in terms of blood glucose area under the curve (p = 0.78), mean blood glucose levels (p = 0.28), GV (p = 0.59), and time in range (p = 0.567). FFA and total triglyceride levels were higher in the D1 group (p < 0.014 and p = 0.002, respectively). Different diets may increase the risk of cardiovascular diseases by affecting GI, FFA, and blood glucose levels.

Pairing Evidence-Based Strategies With Motivational Interviewing to Support Optimal Nutrition and Weight Gain in Pregnancy

OBJECTIVE

Because eating, nutrition, and weight management patterns adopted during pregnancy may persist beyond the postpartum period, pregnancy provides an opportunity for health education that affects the future health of the pregnant person, the fetus, and the family. This systematic review aimed to find nutrition and weight management behaviors that could be used safely during pregnancy to optimize gestational weight gain.

METHODS

PubMed, MEDLINE, and Web of Science were searched for research or systematic reviews published in English from 2018 to 2023 using terms including gestational weight gain maintenance, weight, management, pregnancy, behavior, strategy, and strategies. Excluded research used pediatric or adolescent populations, restrictive diets such as no carbohydrate or no fat diets, fasting, bariatric surgery, weight loss medications, private industry, or profit-earning programs using food brands or specific diet programs.

RESULTS

The abstracts reviewed in these areas: excessive gestational weight gain (1019), low-glycemic index diet (640), Mediterranean diet (220), MyPlate diet (2), the Dietary Approaches to Stop Hypertension (DASH) diet (50), portion control (6), home meal preparation (6), mindful eating (13), intuitive eating (10), self-weighing (10), and motivational interviewing during pregnancy (107), were reduced to 102 studies. Studies in those 10 areas were reviewed for nutrition and eating behaviors that are safe to use during pregnancy and could be used along with motivational interviewing.

CONCLUSION

Clinicians can discuss these behaviors using motivational interviewing techniques to assist clients in optimizing gestational weight gain. Dialogue examples pairing these strategies with motivational interviewing principles are included.

Evidence-Based Eating Patterns and Behavior Changes to Limit Excessive Gestational Weight Gain: A Scoping Review

BACKGROUND

International prenatal care guidelines set a standard for clinicians to discuss gestational weight gain with their patients along with the complications associated with prepregnancy obesity and excessive gestational weight gain. Clinicians often lack evidence-based eating, nutrition, and activity strategies to share with patients.

METHODS

This systematic review aimed to find eating patterns and behaviors that could be used safely during pregnancy to limit excessive gestational weight gain. PubMed, MEDLINE, and Web of Science were searched for research or systematic reviews performed in the United States or Canada and published in English from 2013 to 2023. Keyword search terms included weight, manage, behavior, strategy, strategies, gestational weight gain, and nutrition. Excluded research used pediatric or adolescent populations, restrictive diets, such as no carbohydrate or no fat diets, fasting, bariatric surgery, weight loss medications, private industry or profit-earning programs using food brands, or specific diet programs.

RESULTS

A total of 844 abstracts were retrieved, with 103 full-text studies reviewed. Behaviors had to be useful for maintaining a healthy gestational weight gain and had to be safe for use during pregnancy. Behaviors useful during pregnancy included meal planning, home meal preparation, portion control, using diets such as the Mediterranean diet, the low-glycemic index diet, and the Dietary Approaches to Stop Hypertension diet (DASH), regular physical activity, sleeping 6-7 h a night, mindful eating, intuitive eating, and regular seif-weighing.

CONCLUSION

The evidence-based strategies outlined in this review are safe for use during pregnancy and can assist patients in avoiding excessive gestational weight gain while maintaining the nutrition needed for healthy fetal growth.

Weight loss associated with low-energy diets with different glycaemic loads does not improve arterial stiffness: a randomised clinical trial

We evaluated the effects of two low-energy diets with different glycaemic loads on arterial stiffness in adults with excess weight. This was a 45-day parallel-group, randomised clinical trial including seventy-five participants (20-59 years; BMI 32 kg/m2). They were assigned to two similar low-energy diets (reduction of ∼750 kcal.d-1) with macronutrient composition (55 % carbohydrates, 20 % proteins and 25 % lipids) but different glycaemic loads: high-glycaemic load (HGL 171 g.d-1; n 36) or low-glycaemic load (LGL 67 g.d-1; n 39). We evaluated: arterial stiffness (pulse wave velocity, PWV); augmentation index (AIx@75); reflection coefficient; fasting blood glucose; fasting lipid profile; blood pressure and body composition. We found no improvements in PWV (P = 0·690) and AIx@75 (P = 0·083) in both diet groups, but there was a decrease in the reflection coefficient in the LGL group (P = 0·003) compared with baseline. The LGL diet group showed reductions in body weight (Δ -4·9 kg; P = 0·001), BMI (Δ -1·6 kg/m2; P = 0·001), waist circumference (Δ -3·1 cm; P = 0·001), body fat (Δ -1·8 %; P = 0·034), as well as TAG (Δ -14·7 mg/dl; P = 0·016) and VLDL (Δ -2·8 mg/dl; P = 0·020). The HGL diet group showed a reduction in total cholesterol (Δ -14·6 mg/dl; P = 0·001), LDL (Δ -9·3 mg/dl; P = 0·029) but a reduction in HDL (Δ -3·7 mg/dl; P = 0·002). In conclusion, a 45-day intervention with low-energy HGL or LGL diets in adults with excess weight was not effective to improve arterial stiffness. However, the LGL diet intervention was associated with a reduction of reflection coefficient and improvements in body composition, TAG and VLDL levels.

How Could Taxes on Sugary Drinks and Foods Help Reduce the Burden Of Type 2 Diabetes?

PURPOSE OF REVIEW

Taxes on sugary drinks and foods have emerged as a key strategy to counteract the alarming levels of diabetes worldwide. Added sugar consumption from industrialized foods and beverages has been strongly linked to type 2 diabetes. This review provides a synthesis of evidence on how taxes on sugary products can influence the onset of type 2 diabetes, describing the importance of the different mechanisms through which the consumption of these products is reduced, leading to changes in weight and potentially a decrease in the incidence of type 2 diabetes.

RECENT FINDINGS

Observational studies have shown significant reductions in purchases, energy intake, and body weight after the implementation of taxes on sugary drinks or foods. Simulation studies based on the association between energy intake and type 2 diabetes estimated the potential long-term health and economic effects, particularly in low- and middle-income countries, suggesting that the implementation of sugary food and beverage taxes may have a meaningful impact on reducing type 2 diabetes and complications. Public health response to diabetes requires multi-faceted approaches from health and non-health actors to drive healthier societies. Population-wide strategies, such as added sugar taxes, highlight the potential benefits of financial incentives to address behaviors and protective factors to significantly change an individual's health trajectory and reduce the onset of type 2 diabetes worldwide, both in terms of economy and public health.

Recent Advances in Nutraceuticals for the Treatment of Sarcopenic Obesity

Sarcopenic obesity, low muscle mass, and high body fat are growing health concerns in the aging population. This review highlights the need for standardized criteria and explores nutraceuticals as potential therapeutic agents. Sarcopenic obesity is associated with insulin resistance, inflammation, hormonal changes, and reduced physical activity. These factors lead to impaired muscle activity, intramuscular fat accumulation, and reduced protein synthesis, resulting in muscle catabolism and increased fat mass. Myostatin and irisin are myokines that regulate muscle synthesis and energy expenditure, respectively. Nutritional supplementation with vitamin D and calcium is recommended for increasing muscle mass and reducing body fat content. Testosterone therapy decreases fat mass and improves muscle strength. Vitamin K, specifically menaquinone-4 (MK-4), improves mitochondrial function and reduces muscle damage. Irisin is a hormone secreted during exercise that enhances oxidative metabolism, prevents insulin resistance and obesity, and improves bone quality. Low-glycemic-index diets and green cardamom are potential methods for managing sarcopenic obesity. In conclusion, along with exercise and dietary support, nutraceuticals, such as vitamin D, calcium, vitamin K, and natural agonists of irisin or testosterone, can serve as promising future therapeutic alternatives.

The Effectiveness of a Low Glycemic Index/Load Diet on Cardiometabolic, Glucometabolic, and Anthropometric Indices in Children with Overweight or Obesity: A Systematic Review and Meta-Analysis

(1) Background: This systematic review and meta-analysis aims to evaluate the impact of a low glycemic index (LGI) and low glycemic load (LGL) diet on children with overweight and obesity, analyzing any changes in anthropometric, cardiometabolic, and glucometabolic parameters. (2) Methods: Three electronic databases (PubMed, Scopus, CENTRAL), as well as clinical trial registries and reference lists of the included studies, were searched for eligible randomized control trials (RCTs). Two independent reviewers performed the screening of the studies, data extraction, and risk of bias assessment. Mean difference (MD) and 95% confidence intervals (CI) using a random effects model were calculated for each outcome. (3) Results: Eleven RCTs (n = 634) examining the effect of LGI diet versus control were identified. The synthesized data provided from the RCTs indicate no difference between intervention and control groups regarding primary outcomes (body weight (MD: -0.14; 95% CI -1.93 to 1.64, 5 trials), body mass index (BMI) (MD: -0.31; 95% CI -0.85 to 0.23, 6 trials), BMI z-score (MD: -0.03; 95% CI -0.09 to 0.02, 5 trials), and waist circumference (MD: -0.52; 95% CI -2.35 to 1.31, 5 trials)) and other measures of cardiometabolic and glucometabolic parameters. The majority of trials were classified as "some concerns". (4) Conclusions: LGI and LGL diets do not seem to be associated with changes in adiposity, cardiometabolic or glucometabolic markers in children with overweight or obesity. Further research comparing the LGI diet to a high glycemic index diet, with proper methodological standards, is required to clarify the benefits of a LGI diet in this population.

The PCOS puzzle: putting the pieces together for optimal care

Polycystic ovary syndrome (PCOS) is a multifaceted hormonal disorder that has significant ramifications for both women's reproductive and metabolic well-being. This analysis aims to offer a thorough comprehension of PCOS by investigating the various contributing factors that are crucial for its effective management. We delve into the topic of hormonal imbalances, such as elevated androgens and disrupted estrogen-progesterone dynamics, and their effects on reproductive and metabolic health. Furthermore, we explore the intricate connection between insulin resistance, hyperinsulinemia, and PCOS, highlighting their pivotal role in metabolic dysfunction. Additionally, we examine fertility challenges, irregular menstrual patterns, and metabolic complications while also reviewing current treatment methodologies. Moreover, we address the latest research concerning genetic, environmental, and epigenetic influences on PCOS. By piecing together these essential elements, healthcare professionals can attain a comprehensive understanding of PCOS and deliver optimal care for those affected by the condition.

Low glycaemic index or low glycaemic load diets for people with overweight or obesity

BACKGROUND

The prevalence of obesity is increasing worldwide, yet nutritional management remains contentious. It has been suggested that low glycaemic index (GI) or low glycaemic load (GL) diets may stimulate greater weight loss than higher GI/GL diets or other weight reduction diets. The previous version of this review, published in 2007, found mainly short-term intervention studies. Since then, randomised controlled trials (RCTs) with longer-term follow-up have become available, warranting an update of this review.

OBJECTIVES

To assess the effects of low glycaemic index or low glycaemic load diets on weight loss in people with overweight or obesity.

SEARCH METHODS

We searched CENTRAL, MEDLINE, one other database, and two clinical trials registers from their inception to 25 May 2022. We did not apply any language restrictions.

SELECTION CRITERIA

We included RCTs with a minimum duration of eight weeks comparing low GI/GL diets to higher GI/GL diets or any other diets in people with overweight or obesity.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We conducted two main comparisons: low GI/GL diets versus higher GI/GL diets and low GI/GL diets versus any other diet. Our main outcomes included change in body weight and body mass index, adverse events, health-related quality of life, and mortality. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

In this updated review, we included 10 studies (1210 participants); nine were newly-identified studies. We included only one study from the previous version of this review, following a revision of inclusion criteria. We listed five studies as 'awaiting classification' and one study as 'ongoing'. Of the 10 included studies, seven compared low GI/GL diets (233 participants) with higher GI/GL diets (222 participants) and three studies compared low GI/GL diets (379 participants) with any other diet (376 participants). One study included children (50 participants); one study included adults aged over 65 years (24 participants); the remaining studies included adults (1136 participants). The duration of the interventions varied from eight weeks to 18 months. All trials had an unclear or high risk of bias across several domains.  Low GI/GL diets versus higher GI/GL diets Low GI/GL diets probably result in little to no difference in change in body weight compared to higher GI/GL diets (mean difference (MD) -0.82 kg, 95% confidence interval (CI) -1.92 to 0.28; I2 = 52%; 7 studies, 403 participants; moderate-certainty evidence). Evidence from four studies reporting change in body mass index (BMI) indicated low GI/GL diets may result in little to no difference in change in BMI compared to higher GI/GL diets (MD -0.45 kg/m2, 95% CI -1.02 to 0.12; I2 = 22%; 186 participants; low-certainty evidence)at the end of the study periods. One study assessing participants' mood indicated that low GI/GL diets may improve mood compared to higher GI/GL diets, but the evidence is very uncertain (MD -3.5, 95% CI -9.33 to 2.33; 42 participants; very low-certainty evidence). Two studies assessing adverse events did not report any adverse events; we judged this outcome to have very low-certainty evidence. No studies reported on all-cause mortality.    For the secondary outcomes, low GI/GL diets may result in little to no difference in fat mass compared to higher GI/GL diets (MD -0.86 kg, 95% CI -1.52 to -0.20; I2 = 6%; 6 studies, 295 participants; low certainty-evidence). Similarly, low GI/GL diets may result in little to no difference in fasting blood glucose level compared to higher GI/GL diets (MD 0.12 mmol/L, 95% CI 0.03 to 0.21; I2 = 0%; 6 studies, 344 participants; low-certainty evidence).  Low GI/GL diets versus any other diet Low GI/GL diets probably result in little to no difference in change in body weight compared to other diets (MD -1.24 kg, 95% CI -2.82 to 0.34; I2 = 70%; 3 studies, 723 participants; moderate-certainty evidence). The evidence suggests that low GI/GL diets probably result in little to no difference in change in BMI compared to other diets (MD -0.30 kg in favour of low GI/GL diets, 95% CI -0.59 to -0.01; I2 = 0%; 2 studies, 650 participants; moderate-certainty evidence). Two adverse events were reported in one study: one was not related to the intervention, and the other, an eating disorder, may have been related to the intervention. Another study reported 11 adverse events, including hypoglycaemia following an oral glucose tolerance test. The same study reported seven serious adverse events, including kidney stones and diverticulitis. We judged this outcome to have low-certainty evidence. No studies reported on health-related quality of life or all-cause mortality. For the secondary outcomes, none of the studies reported on fat mass. Low GI/GL diets probably do not reduce fasting blood glucose level compared to other diets (MD 0.03 mmol/L, 95% CI -0.05 to 0.12; I2 = 0%; 3 studies, 732 participants; moderate-certainty evidence).  AUTHORS' CONCLUSIONS: The current evidence indicates there may be little to no difference for all main outcomes between low GI/GL diets versus higher GI/GL diets or any other diet. There is insufficient information to draw firm conclusions about the effect of low GI/GL diets on people with overweight or obesity. Most studies had a small sample size, with only a few participants in each comparison group. We rated the certainty of the evidence as moderate to very low. More well-designed and adequately-powered studies are needed. They should follow a standardised intervention protocol, adopt objective outcome measurement since blinding may be difficult to achieve, and make efforts to minimise loss to follow-up. Furthermore, studies in people from a wide range of ethnicities and with a wide range of dietary habits, as well as studies in low- and middle-income countries, are needed.

Moderating "the great debate": The carbohydrate-insulin vs. the energy balance models of obesity

The increased prevalence of obesity in recent decades is a topic of great scientific and medical interest, but despite many advances, the causes of this increase have not been adequately identified. In this context, two conflicting models for obesity-the carbohydrate-insulin model (CIM) and the energy balance model (EBM)-are being vigorously debated by distinct cohorts of experts in the field. The goal of this perspective is to assess this "conflict of models" from a neutral perspective. I conclude that although both models have produced useful insights, they differ fundamentally in what they seek to explain, and neither has yet provided a validated mechanistic account for the rising obesity prevalence in some but not all members of the population. Rather than engaging in such debates over competing models, the field should be more focused on establishing specific mechanistic insights in identified patient groups and, eventually, actionable interventions based on them.

The Impact of Free Sugar on Human Health-A Narrative Review

The importance of nutrition in human health has been understood for over a century. However, debate is ongoing regarding the role of added and free sugars in physiological and neurological health. In this narrative review, we have addressed several key issues around this debate and the major health conditions previously associated with sugar. We aim to determine the current evidence regarding the role of free sugars in human health, specifically obesity, diabetes, cardiovascular diseases, cognition, and mood. We also present some predominant theories on mechanisms of action. The findings suggest a negative effect of excessive added sugar consumption on human health and wellbeing. Specific class and source of carbohydrate appears to greatly influence the impact of these macronutrients on health. Further research into individual effects of carbohydrate forms in diverse populations is needed to understand the complex relationship between sugar and health.

Determining Dietary Patterns to Recommend for Type 2 Diabetes: An Umbrella Review

Some specific dietary patterns improve glycaemic levels and cardiovascular risk factors better than others. We aimed to identify the most effective dietary patterns using a food-focused approach to improve blood glucose management (primary outcome) and cardiovascular risk factors (secondary outcome) in people with type 2 diabetes. An umbrella review was conducted comparing dietary patterns for the management of these outcomes. Studies published between 2012 and 2022 were identified using PubMed Central, ProQuest, Web of Science, and the Cochrane Database of Systematic Reviews. Thirty systematic reviews met the inclusion criteria. Twenty-two of thirty reviews quantitated (via meta-analyses of over 212 randomised control trials) the effect size of different dietary patterns. Twelve reviews found Low-carbohydrate (LC), Mediterranean (M), Plant-based (PB), and/or Low-glycaemic Index (LGI) diets reduced HbA1c moderately more than control diets (typically a high-carbohydrate, low-fat diet) (i.e., LC: -0.1 to -0.5%; M: -0.3 to -0.5%; PB: -0.2 to -0.4%; LGI -0.2 to -0.5%; all p-value < 0.01). We conclude that Low-carbohydrate, Mediterranean, Plant-based, and Low-glycaemic Index dietary patterns are all clinically effective for people with type 2 diabetes as alternatives to high-carbohydrate, low-fat diets typically used for managing glycaemic levels and CVD risk. However, quality evidence about the sustainability of effects and safety remains limited, warranting future research.

Low glycaemic index and glycaemic load diets in adults with excess weight: Systematic review and meta-analysis of randomised clinical trials

BACKGROUND

To compare the effects of low and high glycaemic index/glycaemic load (GI/GL) diets on body weight in adults with excess weight.

METHODS

We searched for randomised controlled trials comparing low GI/GL vs. high GI/GL diets from Medline (via PubMed), Embase, Scopus and Web of Science. The variables of interest were anthropometric measurements, fasting glucose and fasting insulin levels and lipid profile, and 10 studies were included in the meta-analysis.

RESULTS

The sample size ranged from 19 to 203 participants. Low GI/GL is not superior to high GI/GL diets on body weight reduction in adults with excess weight (body mass index [BMI] ≥ 25 kg m^-2 ). However, low GI/GL diets show greater body weight reductions in adults with BMI ≥ 30 kg m^-2 (-0.93 kg; 95% confidence interval [CI] = -1.73 to -0.12; p = 0.045). Compared with high GI/GL diets, low GI/GL diets may also help reduce fasting glucose (-1.97 mg dl^-1 ; 95% CI = -3.76 to 0.19; p = 0.030) and fasting insulin (-0.55 µU ml^-1 ; 95% CI = -0.95 to -0.15; p = 0.007). No differences in fat mass, fat-free mass, waist circumference and lipid profile were observed between low GI/GL and high GI/GL diets. The risk of bias for body weight was classified as 'low risk' (25% of the studies) and 'some concerns' for all domains of RoB 2 tool in most studies.

CONCLUSIONS

When compared with high GI/GL diets, low GI/GL diets appear to more effectively reduce fasting glucose and insulin and promote greater body weight reduction in adults with obesity (BMI ≥ 30 kg m^-2 ).

Comparison of Glycemic Response to Carbohydrate Meals without or with a Plant-Based Formula of Kidney Bean Extract, White Mulberry Leaf Extract, and Green Coffee Extract in Individuals with Abdominal Obesity

Due to the rising prevalence of obesity and type 2 diabetes, a strategy that can positively influence diet quality in a simple way is being explored, since a low glycemic index (GI) diet is advised in the dietoprophylaxis and diet therapy of diabetes. Methods: Twenty-three women with abdominal obesity participated in the study. The postprandial glycemic response and glycemic index were determined after three carbohydrate meals (noodle soup, white rice, strawberry sorbet) without or with the addition of a plant-base supplement (extracts of kidney bean, white mulberry leaf, and green coffee) with a potentially hypoglycemic effect. For two products (instant noodle soup and white rice), the addition of the plant supplement resulted in a reduction in glicemic iAUC values (respectively, by: 17.1%, p = 0.005 and 5.3%; p = 0.03; 40.6%, p = 0.004 and 5.3%, p = 0.019). However, this effect was not observed for strawberry sorbet. The blood glucose concentrations 30 min after the consumption of instant noodle soup and white rice with the plant-based formula addition significantly affected the GI value of tested meals (p = 0.0086, r = 0.53; p = 0.0096, r = 0.53), which may indicate the effect of this plant supplement on enterohormone and/or insulin secretion. Conclusion: A formula containing kidney bean, white mulberry leaves, and green coffee extracts may therefore be a notable factor in lowering postprandial glycemia and the GI of carbohydrate foods. However, further research is needed to determine for which food groups and meals its use may be most effective.

Utilising a Real-Time Continuous Glucose Monitor as Part of a Low Glycaemic Index and Load Diet and Determining Its Effect on Improving Dietary Intake, Body Composition and Metabolic Parameters of Overweight and Obese Young Adults: A Randomised Controlled Trial

A randomised controlled trial to measure the effects of integrating real-time continuous glucose monitor (rtCGM) into a low glycaemic index (GI) and glycaemic load (GL) dietary intervention on dietary intake, body composition and specific metabolic parameters was carried out. A total of 40 overweight young adults [(means ± SD) age: 26.4 ± 5.3 years, BMI: 29.4 ± 4.7 kg/m2] were randomised into an intervention and control groups for a period of eight weeks. Both groups received nutrition education on low GI and GL foods. The intervention group also received an rtCGM system to monitor their glucose levels 24 h a day. While controlling for physical activities and GI and GL nutrition knowledge, the results indicated that the rtCGM system further improved body weight, BMI, fat mass, fasting plasma glucose, HbA1c, total cholesterol, HDL cholesterol and LDL cholesterol in the intervention group (p < 0.05). This trial unveils the robustness of the rtCGM where non-diabetic overweight and obese young adults can benefit from this device and utilise it as a management tool for overweight and obesity and a primary prevention tool for type 2 diabetes, as it provides real-time and personalised information on physiological changes.

The energy balance model of obesity: beyond calories in, calories out

A recent Perspective article described the "carbohydrate-insulin model (CIM)" of obesity, asserting that it "better reflects knowledge on the biology of weight control" as compared with what was described as the "dominant energy balance model (EBM)," which fails to consider "biological mechanisms that promote weight gain." Unfortunately, the Perspective conflated and confused the principle of energy balance, a law of physics that is agnostic as to obesity mechanisms, with the EBM as a theoretical model of obesity that is firmly based on biology. In doing so, the authors presented a false choice between the CIM and a caricature of the EBM that does not reflect modern obesity science. Here, we present a more accurate description of the EBM where the brain is the primary organ responsible for body weight regulation operating mainly below our conscious awareness via complex endocrine, metabolic, and nervous system signals to control food intake in response to the body's dynamic energy needs as well as environmental influences. We also describe the recent history of the CIM and show how the latest "most comprehensive formulation" abandons a formerly central feature that required fat accumulation in adipose tissue to be the primary driver of positive energy balance. As such, the new CIM can be considered a special case of the more comprehensive EBM but with a narrower focus on diets high in glycemic load as the primary factor responsible for common obesity. We review data from a wide variety of studies that address the validity of each model and demonstrate that the EBM is a more robust theory of obesity than the CIM.

Associations of Glycemic Index and Glycemic Load with Cardiovascular Disease: Updated Evidence from Meta-analysis and Cohort Studies

PURPOSE OF REVIEW

Diet and lifestyle patterns are considered major contributory factors for cardiovascular disease (CVD) and mortality. In particular, consuming a diet higher in carbohydrates (not inclusive of fruits and vegetables, but more processed carbohydrates) has been associated with metabolic abnormalities that subsequently may increase the risk of CVD and related mortality. Glycemic index (GI) and glycemic load (GL) are values given to foods based on how fast the body converts carbohydrates into glucose also referred to as the glycemic burden of carbohydrates from foods. Conflicting associations of how high GI and GL influence CVDs have been observed even in high-quality meta-analysis studies. We synthesize and report the associations of high GI and GL with various CVDs by sex, obesity, and geographical locations using an updated review of meta-analysis and observational studies.

RECENT FINDINGS

We identified high GI or high GL is associated with an increased risk of CVD events including diabetes (DM), metabolic syndrome (MS), coronary heart disease (CHD), stroke, and stroke mortality in the general population, and the risk of CVD outcomes appears to be stratified by sex, obesity status, and preexisting CVD. Both high GI and GL are associated with DM and CHD in the general population. However, high GI is strongly associated with DM/MS, while high GL is strongly associated with an increased risk of CHD in females. In addition, high GL is also associated with incident stroke, and appears to be associated with CVD mortality in subjects with preexisting CVD or high BMI and all-cause mortality in non-obese DM subjects. However, high GI appears to be associated with CVD or all-cause mortality only in females without CVD. High GI/GL is an important risk factor for CVD outcomes in the general population. High GI seems to be markedly associated with DM/MS, and it may enhance the risk of CVD or all-cause mortality in both sexes and predominately females. Although both high GI and high GL are risk factors for CHD in females, high GL is associated with CVD outcomes in at-risk populations for CVD. These data suggest that while high GI increases the propensity of CVD risk factors and mortality in healthy individuals, high GL contributes to the risk of severe heart diseases including CVD or all-cause mortality, particularly in at-risk populations. These data indicate dietary interventions designed for focusing carbohydrate quality by lowering both GI and GL are recommended for preventing CVD outcomes across all populations.

Low-Glycemic Index Diets as an Intervention in Metabolic Diseases: A Systematic Review and Meta-Analysis

We aimed to investigate the effects of a low-glycemic index (GI) diet on the body mass and blood glucose of patients with four common metabolic diseases by conducting a systematic review and meta-analysis of studies comparing a low-GI diet (LGID) and other types of diet. Search terms relating to population, intervention, comparator, outcomes, and study design were used to search three databases: PubMed, Embase, and the Cochrane Library. We identified 24 studies involving 2002 participants. Random-effects models were used for 16 studies in the meta-analysis and stratified analyses were performed according to the duration of the intervention. The systematic review showed that LGIDs slightly reduced body mass and body mass index (BMI) (p < 0.05). BMI improved more substantially after interventions of >24 weeks and there was no inter-study heterogeneity (I² = 0%, p = 0.48; mean difference (MD) = -2.02, 95% confidence interval (CI): -3.05, -0.98). Overall, an LGID had superior effects to a control diet on fasting blood glucose (FBG) and glycosylated hemoglobin. When the intervention exceeded 30 days, an LGID reduced FBG more substantially (MD = -0.34, 95% CI: -0.55, -0.12). Thus, for patients with metabolic diseases, an LGID is more effective at controlling body mass and blood glucose than a high-GI or other diet.

Weight Loss Strategies

Lifestyle interventions for weight loss combine support for changing diet and physical activity with weight management education and are considered the first line treatment for obesity. A variety of diet-focused interventions including time-restricted eating are also increasingly being promoted for weight management. This chapter reviews different types of interventions for weight management, their underlying health behavior change models, and effectiveness to date in randomized trials. The results justify increasing efforts to improve program effectiveness generally, and to personalize interventions to support long-term adherence. The high prevalence of obesity worldwide, combined with the known increase in risk of non-communicable diseases with duration of excess weight, provides a compelling justification for routine delivery of effective weight management interventions in the community and in clinical care.

Using Dietary Macronutrient Patterns to Predict Sarcopenic Obesity in Older Adults: A Representative Korean Nationwide Population-Based Study

Older adults with sarcopenic obesity (SO) are at increased risk of adverse health outcomes. It has not been identified which pattern of macronutrient intake is appropriate in relation to SO. We aimed to compare the patterns of macronutrient intake for predicting SO in older adults. Data from a total of 3828 older adults who participated in the 2008–2011 Korea National Health and Nutrition Examination Survey were analyzed. The one-day 24 h dietary recall method was used to assess macronutrient intake. SO was defined by a combination of body mass index (BMI) ≥ 25 kg/m² and BMI adjusted-appendicular skeletal muscle mass <0.789 for men and <0.512 for women. Weighted logistic regression analysis revealed the odds ratio (95% confidence interval) for SO of total calorie intake per 100 increments and carbohydrate (CHO) intake (g/kg/day) per 1 increment to be 0.95 (0.91–0.99) and 0.83 (0.74–0.94), respectively, after adjusting for confounding variables in women. The predictive power for SO of CHO intake (g/kg/day) was higher compared with the other patterns of macronutrient intake both in men and women. In conclusion, total calorie intake and CHO intake (g/kg/day) are inversely related to SO in women. CHO intake (g/kg/day) could be the best index for determining SO.

Nonsurgical weight loss interventions: A systematic review of systematic reviews and meta-analyses

Access to bariatric surgery to treat obesity is limited and has long wait times. Many adults are seeking nonsurgical weight loss support. Our study objective was to conduct a systematic review of nonsurgical weight loss interventions. PubMed, EMBASE, CINAHL, PsycInfo, and the CochraneLibrary were searched. Inclusion criteria were adults 18 + with a BMI > 25 enrolled in minimum a 3-month nonsurgical weight loss intervention. Studies were independently extracted and assessed for quality using A MeaSurement Tool to Assess systematic Reviews 2 (AMSTAR2). Pooled analyses were extracted, graded for evidence quality, and summarized. A total of 1065 studies were assessed for eligibility; 815 screened and 236 full-texts assessed. Sixty-four meta-analyses met eligibility criteria: 1180 RCTs with 184,605 study participants. Studies were categorized as diets (n = 13), combination therapies (n = 10), alternative (n = 16), technology (n = 10), behavioral (n = 5), physical activity (n = 6), and pharmacotherapy (n = 3). In 80% of studies, significant weight losses were reported ranging from 0.34-8.73 k in favor of the intervention. The most effective nonsurgical weight loss interventions were diets, either low-carbohydrate or low-fat diets, followed for 6 months; combination therapy including meal replacements plus enhanced support; and pharmacotherapy followed for 12 months. Although significant weight losses were reported for other types of interventions such as physical activity and technology, the majority of studies reported weight losses less than 2 kgs.

Benefits of Low Carbohydrate Diets: a Settled Question or Still Controversial?

PURPOSE OF REVIEW

The purpose of this review was to provide an update on the available data on the benefits of low-carbohydrate (low-carb) diets for weight management and type 2 diabetes (T2DM) and determine if low-carb diets were a settled question or still controversial.

RECENT FINDINGS

Most of the recent published literature in this area consists of reviews of past trials, with a relatively smaller number of recent trials. Low-carb is most commonly compared to low-fat, with problematically inconsistent definitions of both. There are numerous challenges in trying to draw clear conclusions about efficacy and effectiveness. Short-term vs. long-term effects can differ, which is likely impacted by adherence. Adherence is very different between metabolic chamber or feeding studies vs. free-living. Body weight alone is a crude measure that fails to capture potentially important differences in lean-mass, fat-mass, and body water. Benefits for glycemic control need to be balanced with impacts on non-glycemic outcomes such as LDL-cholesterol, the microbiome, and inflammation. It is important to differentiate between low-carb and very-low carbohydrate diets (VLCD). To date no large-scale long-term clinical trials have been conducted testing whether low-carb diets can prevent T2DM. Many issues regarding benefits and risks of low-carb diets remain controversial or unresolved, particularly for VLCD. Some of the recent, better studies highlighted in this review suggest strategies for resolving these controversies.

Metabolic Derangement in Pediatric Patient with Obesity: The Role of Ketogenic Diet as Therapeutic Tool

Obesity is defined as a condition characterized by an excessive fat accumulation that has negative health consequences. Pediatric obesity is associated with an increased risk for many diseases, including impaired glycemic and lipidic control that may lead to the development of chronic, and potentially disabling, pathologies, such as type 2 diabetes mellitus (T2DM) and cardiovascular events, in adult life. The therapeutic strategy initially starts with interventions that are aimed at changing lifestyle and eating behavior, to prevent, manage, and potentially reverse metabolic disorders. Recently, the ketogenic diet (KD) has been proposed as a promising dietary intervention for the treatment of metabolic and cardiovascular risk factors related to obesity in adults, and a possible beneficial role has also been proposed in children. KD is very low in carbohydrate, high in fat, and moderate to high in protein that may have the potential to promote weight loss and improve lipidic derangement, glycemic control, and insulin sensitivity. In this review, we present metabolic disorders on glycemic and lipidic control in children and adolescents with obesity and indication of KD in pediatrics, discussing the role of KD as a therapeutic tool for metabolic derangement. The results of this review may suggest the validity of KD and the need to further research its potential to address metabolic risk factors in pediatric obesity.

Perspective: Does Glycemic Index Matter for Weight Loss and Obesity Prevention? Examination of the Evidence on "Fast" Compared with "Slow" Carbs

High-glycemic index (high-GI) foods (so-called fast carbs) have been hypothesized to promote fat storage and increase risk of obesity. To clarify whether dietary GI impacts body weight, we searched PubMed and the Cochrane Database of Systematic Reviews for observational studies reporting associations between BMI and dietary GI, and for meta-analyses of randomized controlled trials (RCTs) comparing low-GI and high-GI diets for weight loss. Data on 43 cohorts from 34 publications, totaling 1,940,968 adults, revealed no consistent differences in BMI when comparing the highest with the lowest dietary GI groups. In the 27 cohort studies that reported results of statistical comparisons, 70% showed that BMI was either not different between the highest and lowest dietary GI groups (12 of 27 cohorts) or that BMI was lower in the highest dietary GI group (7 of 27 cohorts). Results of 30 meta-analyses of RCTs from 8 publications demonstrated that low-GI diets were generally no better than high-GI diets for reducing body weight or body fat. One notable exception is that low-GI diets with a dietary GI at least 20 units lower than the comparison diet resulted in greater weight loss in adults with normal glucose tolerance but not in adults with impaired glucose tolerance. While carbohydrate quality, including GI, impacts many health outcomes, GI as a measure of carbohydrate quality appears to be relatively unimportant as a determinant of BMI or diet-induced weight loss. Based on results from observational cohort studies and meta-analyses of RCTs, we conclude that there is scant scientific evidence that low-GI diets are superior to high-GI diets for weight loss and obesity prevention.

A Western-style diet interacts with genetic variants of the LDL receptor to hyper-LDL cholesterolemia in Korean adults

OBJECTIVE

To evaluate the association of genetic risk scores (GRS) of LDLR, APOB and proprotein convertase subtilisin-kexin type 9 (PCSK9) SNP and plasma LDL concentrations and to identify lifestyle interactions with the GRS in Korean middle-aged adults.

DESIGN

Korean genome and epidemiology study (KoGES) was conducted to determine genetic variants and lifestyle factors, including nutrient intakes, in a retrospective hospital-based city cohort conducted by the Korean Center for Disease and Control during 2004-2013.

SETTINGS

Hospitals in Korea.

PARTICIPANTS

Adults aged 40-77 years (n 28 445) without serious diseases.

RESULTS

Subjects with the major alleles (risk allele) of LDLR rs1433099 and rs11557092, APOB rs13306194 and PCSK9 rs11583723 had higher plasma LDL concentration by 1·20-folds than those with the minor alleles. Subjects with High-GRS (major alleles) of the four SNP had higher adjusted OR for plasma total and LDL-cholesterol and TAG concentrations by 1·24-, 1·203- and 1·167-folds, respectively, but not HDL-cholesterol, than those with Low-GRS. Western-style flour-rich dietary patterns, but not balanced Korean-style and rice-based dietary patterns, had interactions with GRS to increase plasma LDL concentrations. Daily energy intake also interacted with GRS. In the high intake of Western-style flour-rich dietary patterns, carriers with High-GRS had much higher plasma LDL concentrations than the Low-GRS. With high energy intake, carriers with High-GRS had much higher plasma LDL concentrations than those with Low-GRS.

CONCLUSIONS

Adults with major alleles of four SNP are recommended to have low-energy intakes with a balanced Korean diet need to avoid high-energy intakes especially with Western-style flour-rich diet patterns.

High-Protein or Low Glycemic Index Diet-Which Energy-Restricted Diet Is Better to Start a Weight Loss Program?

BACKGROUND

To date, no crossover studies have compared the effects of high-protein (HP) and low glycemic index (LGI) diets applied as starting energy-restricted diets.

METHODS

Thirty-five overweight or obese volunteers with sedentary lifestyles aged 41.4 ± 11.0 years, with body mass index (BMI) of 33.6 ± 4.2 kg/m2, without diabetes, completed an 8-week randomized crossover study of an energy-restricted diet (reduction of 30%; approximately 600 kcal/day). The anthropometric parameters, body composition, 24 h blood pressure, and basic metabolic profile were measured at baseline and after completing the two 4-week diets; i.e., the HP (protein at 30% of the daily energy intake) or LGI diet, followed by the opposite diet. All subjects maintained food diaries and attended six counselling sessions with a clinical dietitian.

RESULTS

The final weight loss was not significantly different when the HP diet was used first but was associated with a greater loss of fat mass: 4.6 kg (5.8; 3.0 kg) vs. 2.2 (4.5; 0.8); p < 0.025, preserved muscle mass, and reduced LDL-cholesterol.

CONCLUSIONS

A short-term HP diet applied as a jump-start diet appeared to be more beneficial than an LGI diet, as indicated by the greater fat mass loss, preservation of muscle mass, and better effects on the lipid profile.

The importance of glycemic index on post-prandial glycaemia in the context of mixed meals: A randomized controlled trial on pasta and rice

BACKGROUND AND AIMS

Post-prandial glycemic response (PPGR) depends on the intrinsic characteristic of the carbohydrate-rich foods as well as on the amount and type of other nutrients. This study aimed to explore whether the addition of condiments can affect the difference in PPGR between a low and a medium-high Glycemic Index (GI) food.

METHODS AND RESULTS

Spaghetti (S) and rice ® were consumed plain and after adding tomato sauce and extra virgin olive oil (TEVOO), or pesto sauce (P). The GI of R (63 ± 3) was statistically higher than that of S (44 ± 7) (p = 0.003). The Incremental Area Under the Curve (IAUC) for R was significantly greater than S (124.2 ± 12.1 and 82.1 ± 12.9 mmol∗min/L respectively) (p = 0.016) for blood glucose but not for insulin (1192.6 ± 183.6 and 905.2 ± 208.9 mU∗min/L, respectively) (p = 0.076). There were no significant differences after the addition of either TEVOO or P. The postprandial peaks of blood glucose and insulin for R (6.7 ± 0.3 mmol/L and 36.4 ± 4.9 mU/L, respectively) were significantly higher compared to S (6.0 ± 0.2 mmol/L and 26.7 ± 3.6 mU/L, respectively) (p = 0.033 and p = 0.025). The postprandial peak for insulin remained significantly higher with P (36.8 ± 3.7 and 28.6 ± 2.9 mU/L for R + P and S + P, p = 0.045) but not with EVOO (p = 0.963). Postprandial peaks for blood glucose were not significantly different with condiment.

CONCLUSIONS

The differences in PPGR were significant between spaghetti and rice consumed plain, they reduced or disappeared with fat adding, depending on the type of condiment used. REGISTRATION NUMBER: (www.clinicaltrial.gov):NCT03104712.

Effects of Dietary Glycemic Index and Glycemic Load on Cardiometabolic and Reproductive Profiles in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Women with polycystic ovary syndrome (PCOS) exhibit cardiometabolic (e.g., insulin resistance) and associated reproductive disruptions. Lifestyle modification (e.g., diet) is recommended as the first-line therapy to manage PCOS; however, a favorable dietary regimen remains unclear beyond energy restriction. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to summarize evidence on impacts of dietary glycemic index (GI) or glycemic load (GL) on cardiometabolic and reproductive profiles to update the International Evidence-based Guideline for the Assessment and Management of PCOS. Databases of MEDLINE, Cochrane, Web of Science, and Scopus were searched through 30 October 2019, and confirmed on 25 March 2020, to identify RCTs (≥8 wk) comparing the effects of diets with lower (LGI/LGL) and higher (HGI/HGL) GI/GL on glucoregulatory outcomes, lipid profile, anthropometrics, and androgen status in PCOS. The primary outcome was HOMA-IR. Data were pooled by random-effects models and expressed as weighted mean differences and 95% CIs. The risk of bias was assessed by the Cochrane tool. Ten RCTs (n = 403) were eligible. Eight evaluated LGI and 2 LGL diets. LGI diets decreased HOMA-IR (-0.78; -1.20, -0.37; I2 = 86.6%), fasting insulin (-2.39; -4.78, 0.00 μIU/mL; I2 = 76.8%), total cholesterol (-11.13; -18.23, -4.04 mg/dL; I2 = 0.0%), LDL cholesterol (-6.27; -12.01, -0.53 mg/dL; I2 = 0.0%), triglycerides (-14.85; -28.75, -0.95 mg/dL; I2 = 31.0%), waist circumference (-2.81; -4.40, -1.23 cm; I2 = 53.9%), and total testosterone (-0.21; -0.32, -0.09 nmol/L; I2 = 8.6%) compared with HGI diets (all: P ≤ 0.05) without affecting fasting glucose, HDL cholesterol, weight, or free androgen index (all: P ≥ 0.07). Some results were contradictory and only described narratively for 2 RCTs that evaluated LGL diets, since inclusion in meta-analyses was not possible. LGI diets improved glucoregulatory outcomes (HOMA-IR, insulin), lipid profiles, abdominal adiposity, and androgen status, conceivably supporting their inclusion for dietary management of PCOS. Further RCTs should confirm these observations and address whether LGI diets improve more patient-pressing complications, including ovulatory cyclicity, infertility, and cardiovascular disease risk in this high-risk population. This review was registered at www.crd.york.ac.uk/PROSPERO as CRD42020175300.

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.

Effect of alternate-day fasting on obesity and cardiometabolic risk: A systematic review and meta-analysis

BACKGROUND & AIMS

Alternate-day fasting (ADF) is related to weight reduction, lowered risks of weight regain, and relative lean body mass preservation compared to continuous energy restriction. This meta-analysis aimed to assess the effects of ADF on obesity-related factors and cardiometabolic risk factors in adults.

METHODS

Using PubMed, EMBASE, and Cochrane online databases, an electronic search was performed. Randomized controlled trials were investigated to evaluate ADF effects on body mass index (BMI), body weight (BW), waist circumference, body fat mass (FM), lean body mass, and cardiometabolic risk factors in adults aged ≥18 years. By utilizing a random-effects model, meta-analyses to assess weighted mean difference (WMD) with 95% confidence intervals (CIs) were performed for eight randomized controlled trials (total participants = 728).

RESULTS

We observed significant effects of ADF for BMI (WMD -0.73 kg/m², 95% CI -1.13 to -0.34), FM (WMD -1.27 kg, 95% CI -2.09 to -0.46), and total cholesterol (WMD -8.14 mg/dL, 95% CI -14.59 to -1.69). Subgroup analyses indicated that significant intervention effects were observed for BMI, BW, FM, and total cholesterol when compared to the control, the participants were overweight, and the study duration was <6 months. ADF is effective in reducing waist circumference in adults aged ≥40 years with obesity. However, there was no difference between ADF and continuous energy restriction, time-restricted feeding, or control with regard to lean body mass.

CONCLUSIONS

Current evidence suggests that ADF effectively lowers BMI, BW, FM, and total cholesterol in adults with overweight within 6 months compared to the control.

Starch Digestion-Related Amylase Genetic Variants, Diet, and Changes in Adiposity: Analyses in Prospective Cohort Studies and a Randomized Dietary Intervention

Salivary amylase, encoded by the AMY1 gene, is responsible for the digestion of carbohydrates. We investigated associations of AMY1 genetic variations with general and central adiposity changes considering dietary carbohydrate intake among 32,054 adults from four prospective cohort studies. A genetic risk score (GRS) was calculated based on nine AMY1 single-nucleotide polymorphisms, with higher AMY1-GRS indicating higher activity of salivary amylase. We meta-analyzed interactions between AMY1-GRS and dietary intake for changes in general and central adiposity over 5.5-10 years. We found that carbohydrate food intake significantly altered associations of AMY1-GRS with changes in BMI (P interaction = 0.001) and waist circumference (P interaction < 0.001). Results were consistent and significant in female cohorts rather than in male cohorts. Among women, higher AMY1-GRS was associated with more increases in adiposity if dietary carbohydrate food intake was high, while higher AMY1-GRS was associated with less gains in adiposity when the dietary intake was low. Also, in a 2-year randomized dietary intervention trial, associations of AMY1-GRS with changes in weight (P interaction = 0.023) and waist circumference (P interaction = 0.037) were significantly modified by carbohydrate intake. Our results suggest the importance of precision nutrition strategies considering participants' genetic adaptation to carbohydrate-rich diets in regulating general and central adiposity.

Glenn A, M. S. Wolever T, G. Josse R, L. O’Connor D, Thompson A, D. Noseworthy R, Seider M, Sobie M, Bhatti G, Cavanagh J, Jones E, B. Darling P. Evaluation of Glycemic Index Education in People Living with Type 2 Diabetes: Participant Satisfaction, Knowledge Uptake, and Application

The glycemic index (GI) has been included in the Canadian clinical practice guidelines for type 2 diabetes (T2D) management since 2003, and even longer in other parts of the world (e.g., Australia). Despite this, dietitians have reported that GI is "too difficult for patients to understand and apply." They have called for diverse GI-utility data and evidence-informed education materials. To address these concerns, we developed and evaluated a GI education workshop and supporting materials, using the Kirkpatrick Model, for a T2D population. Participants (n = 29) with T2D attended a dietitian-facilitated workshop and received education materials. A mixed-form questionnaire (GIQ) and 3-day-diet-record were used to capture patient demographics, satisfaction, knowledge, and application, prior to and immediately after the workshop, 1-week, and 4-weeks post-education. Dietary GI was significantly lower at 1 and 4 weeks post-education (mean ± SEM; both 54 ± 1), compared to pre-education (58 ± 1; p ≤ 0.001). Participants (28/29) were satisfied with the intervention. The GI knowledge score was significantly higher post-education at baseline (83.5 ± 3.4%; p ≤ 0.001), week one (87.5 ± 2.6%; p = 0.035), and week four (87.6 ± 3.8%; p = 0.011) when compared to pre-education (53.6 ± 5.1%). A significant reduction in dietary GI was achieved by participants living with T2D, after completing the workshop, and they were able to acquire and apply GI knowledge in a relatively short period.

The Impact of Dietary Glycemic Index and Glycemic Load on Postprandial Lipid Kinetics, Dyslipidemia and Cardiovascular Risk

Many recent studies have acknowledged postprandial hypetriglyceridemia as a distinct risk factor for cardiovascular disease. This dysmetabolic state is the result of the hepatic overproduction of very low-density lipoproteins (VLDLs) and intestinal secretion of chylomicrons (CMs), which leads to highly atherogenic particles and endothelial inflammation. Postprandial lipid metabolism does not only depend on consumed fat but also on the other classes of nutrients that a meal contains. Various mechanisms through which carbohydrates exacerbate lipidemia have been identified, especially for fructose, which stimulates de novo lipogenesis. Glycemic index and glycemic load, despite their intrinsic limitations, have been used as markers of the postprandial glucose and insulin response, and their association with metabolic health and cardiovascular events has been extensively studied with contradictory results. This review aims to discuss the importance and pathogenesis of postprandial hypertriglyceridemia and its association with cardiovascular disease. Then, we describe the mechanisms through which carbohydrates influence lipidemia and, through a brief presentation of the available clinical studies on glycemic index/glycemic load, we discuss the association of these indices with atherogenic dyslipidemia and address possible concerns and implications for everyday practice.

Effects of Popular Diets on Anthropometric and Cardiometabolic Parameters: An Umbrella Review of Meta-Analyses of Randomized Controlled Trials

The prevalence of overweight, obesity, and their related complications is increasing worldwide. The purpose of this umbrella review was to summarize and critically evaluate the effects of different diets on anthropometric parameters and cardiometabolic risk factors. Medline, Embase, Scopus, Cochrane Database of Systematic Reviews, and Web of Science, from inception to April 2019, were used as data sources to select meta-analyses of randomized controlled trials that examined the effects of different diets on anthropometric parameters and cardiometabolic risk factors. Strength and validity of the evidence were assessed through a set of predefined criteria. Eighty articles reporting 495 unique meta-analyses were examined, covering a wide range of popular diets: low-carbohydrate (n = 21 articles), high-protein (n = 8), low-fat (n = 9), paleolithic (n = 2), low-glycemic-index/load (n = 12), intermittent energy restriction (n = 6), Mediterranean (n = 11), Nordic (n = 2), vegetarian (n = 9), Dietary Approaches to Stop Hypertension (DASH) (n = 6), and portfolio dietary pattern (n = 1). Great variability in terms of definition of the intervention and control diets was observed. The methodological quality of most articles (n = 65; 81%), evaluated using the "A MeaSurement Tool to Assess systematic Reviews-2" questionnaire, was low or critically low. The strength of evidence was generally weak. The most consistent evidence was reported for the Mediterranean diet, with suggestive evidence of an improvement in weight, BMI, total cholesterol, glucose, and blood pressure. Suggestive evidence of an improvement in weight and blood pressure was also reported for the DASH diet. Low-carbohydrate, high-protein, low-fat, and low-glycemic-index/load diets showed suggestive and/or weak evidence of a reduction in weight and BMI, but contrasting evidence for lipid, glycemic, and blood pressure parameters, suggesting potential risks of unfavorable effects. Evidence for paleolithic, intermittent energy restriction, Nordic, vegetarian, and portfolio dietary patterns was graded as weak. Among all the diets evaluated, the Mediterranean diet had the strongest and most consistent evidence of a beneficial effect on both anthropometric parameters and cardiometabolic risk factors. This review protocol was registered at www.crd.york.ac.uk/PROSPERO/ as CRD42019126103.

A Novel Method to Visualize the Dietary Macronutrient Composition of Smaller Visceral Fat Accumulation

The accumulation of visceral fat is considered a potential cause of a clustering of metabolic disorders including hypertension, hyperglycemia, and dyslipidemia. These disorders are some of the upstream determinants of serious diseases such as coronary heart disease, cerebrovascular disease, and dementia. In particular, the accumulation of visceral fat is considered to have a causal relationship with dietary habits. To clarify this relationship, we characterize dietary habits with dietary macronutrient composition and visceral fat accumulation with a measure of visceral fat area (VFA). We then employ a novel multiple regression model with VFA as the objective variable and macronutrient composition, gender, and age group as explanatory variables. The macronutrient composition is converted by the isometric log-ratio transformation since it is compositional data. The squared term of the transformed macronutrient composition is also included as an explanatory variable. To fit the data to the model, variable selection is performed based on Akaike's information criterion to exclude unnecessary interaction terms. The validity of the model is confirmed by a numerical simulation study. We then cross-sectionally analyze real-world data collected through community-wide health examinations of adults living in the Iwaki district in northern Japan. The macronutrient composition data is taken by the dietary history questionnaire and VFA is measured using a bioimpedance-type visceral fat meter. The main factors of macronutirent composition and their interactions with gender and age group are identified through analysis of variance and are significantly associated with VFA (p < 0.05). Moreover, the predicted VFA corresponding to the macronutrient composition stratified by gender and age group are obtained, and visualized seamlessly on a ternary plot. The results show that a diet with a high ratio of %protein to %fat generally corresponds to a lower VFA level. However, in middle-aged female subjects, higher VFA is found in lower %fat and higher %carbohydrate diets. In summary, the association between VFA and dietary macronutrient composition is significantly modulated depending on gender and age group in Iwaki district's adult population. The novel statistical analysis method in this study is useful in exploring favorable dietary macronutrient composition for lower level of visceral fat accumulation.

Low-glycemic index diets as an intervention for diabetes: a systematic review and meta-analysis

BACKGROUND

Low-glycemic index (GI) diets are thought to reduce postprandial glycemia, resulting in more stable blood glucose concentrations.

OBJECTIVE

We hypothesized that low-GI diets would be superior to other diet types in lowering measures of blood glucose control in people with type 1 or type 2 diabetes, or impaired glucose tolerance.

METHODS

We searched PubMed, the Cochrane Library, EMBASE, and clinical trials registries for published and unpublished studies up until 1 March, 2019. We included 54 randomized controlled trials in adults or children with impaired glucose tolerance, type 1 diabetes, or type 2 diabetes. Continuous data were synthesized using a random effects, inverse variance model, and presented as standardized mean differences with 95% CIs.

RESULTS

Low-GI diets were effective at reducing glycated hemoglobin (HbA1c), fasting glucose, BMI, total cholesterol, and LDL, but had no effect on fasting insulin, HOMA-IR, HDL, triglycerides, or insulin requirements. The reduction in fasting glucose and HbA1c was inversely correlated with body weight. The greatest reduction in fasting blood glucose was seen in the studies of the longest duration.

CONCLUSIONS

Low-GI diets may be useful for glycemic control and may reduce body weight in people with prediabetes or diabetes.

Insulin resistance exhibits varied metabolic abnormalities in nonalcoholic fatty liver disease, chronic hepatitis B and the combination of the two: a cross-sectional study

BACKGROUND

Insulin resistance (IR) related metabolic disorders are associated with a worse prognosis of chronic hepatitis B virus (CHB) infection or nonalcoholic fatty liver disease (NAFLD). However, the relationships among CHB, steatosis, IR and metabolic factors remain controversial. The study aims to evaluate the impact of insulin resistance severity on metabolic profiles in patients with CHB, NAFLD and the coincidence of the two.

METHODS

We conducted a cross-sectional study between January 2011 and December 2018 that included 2768 consecutive Chinese subjects (healthy controls: 667, CHB: 970, NAFLD: 878, CHB with NAFLD: 253). IR was determined with the homeostasis model assessment for insulin resistance (HOMA-IR). Metabolic measures included fasting serum insulin, glucose, lipid profiles and uric acid.

RESULTS

The prevalence of IR was increased in CHB with NAFLD subjects compared with that in control subjects or subjects with CHB or NAFLD alone (41.5% vs 2.9%/11.9%/36.9%, respectively; P < 0.001). Within NAFLD and CHB with NAFLD group, the frequency of metabolic syndrome, hypertension and hyperuricemia increased as the HOMA-IR category increased (P for trend < 0.05). A higher risk for total cholesterol, low-density lipoprotein cholesterol and elevated alanine transaminase was observed with IR in the CHB with NAFLD group compared with that in the other groups, while no stepwise increase in hypertriglyceridemia was found in HOMA-IR in the CHB with NAFLD group.

CONCLUSION

Insulin resistance is highly prevalent in patients with CHB combined with NAFLD, and the increased metabolic risk, rather than hypertriglyceridemia, is driven by IR in CHB combined with NAFLD.