markdownWe present a new tool for meta‐analysis, _Meta‐Essentials_, which is free of charge and easy to use. In this paper, we introduce the tool and compare its features to other tools for meta‐analysis.We also provide detailed information on the validation of the tool. Although free of charge and simple, _Meta‐Essentials_ automatically calculates effect sizes from a wide range of statistics and can be used for a wide range of meta‐analysis applications, including subgroup analysis, moderator analysis, and publication bias analyses. The confidence interval of the overall effect is automatically based on the Knapp‐Hartung adjustment of the DerSimonian‐Laird estimator. However, more advanced meta‐analysis methods such as meta‐analytical structural equation modelling and meta‐regression with multiple covariates are not available. In summary, _Meta‐Essentials_ may prove a valuable resource for meta‐analysts, including researchers, teachers, and students.

Introduction, comparison, and validation of Meta-Essentials : A free and simple tool for meta-analysis

PURPOSE\nTo compare the effects of a low-carbohydrate diet and a conventional (fat- and calorie-restricted) diet on lipoprotein subfractions and inflammation in severely obese subjects.\n\n\nMETHODS\nWe compared changes in lipoprotein subfractions and C-reactive protein levels in 78 severely obese subjects, including 86% with either diabetes or metabolic syndrome, who were randomly assigned to either a low-carbohydrate or conventional diet for 6 months.\n\n\nRESULTS\nSubjects on a low-carbohydrate diet experienced a greater decrease in large very low-density lipoprotein (VLDL) levels (difference = -0.26 mg/dL, P = 0.03) but more frequently developed detectable chylomicrons (44% vs. 22%, P = 0.04). Both diet groups experienced similar decreases in the number of low-density lipoprotein (LDL) particles (difference = -30 nmol/L, P = 0.74) and increases in large high-density lipoprotein (HDL) concentrations (difference = 0.70 mg/dL, P = 0.63). Overall, C-reactive protein levels decreased modestly in both diet groups. However, patients with a high-risk baseline level (>3 mg/dL, n = 48) experienced a greater decrease in C-reactive protein levels on a low-carbohydrate diet (adjusted difference = -2.0 mg/dL, P = 0.005), independent of weight loss.\n\n\nCONCLUSION\nIn this 6-month study involving severely obese subjects, we found an overall favorable effect of a low-carbohydrate diet on lipoprotein subfractions, and on inflammation in high-risk subjects. Both diets had similar effects on LDL and HDL subfractions.

A randomized study comparing the effects of a low-carbohydrate diet and a conventional diet on lipoprotein subfractions and C-reactive protein levels in patients with severe obesity

To assess whether low‐carbohydrate (LC) diets are associated with differences in weight loss and well‐being in people with obesity, and their cardiovascular and renal safety.

Effectiveness of low‐carbohydrate diets for long‐term weight loss in obese individuals: A meta‐analysis of randomized controlled trials

Abstract Calorie restriction regimens are popular for their purported health-promoting effects. However, it is unclear whether chronic reduction in energy intake and subsequent weight loss have beneficial effects in the absence of obesity. To this end, the results of studies that examined the effects of the same diet-induced weight loss in individuals with and without obesity were reviewed. The contribution of lean mass to the total amount of weight lost is greater in participants without obesity than in those with obesity, but the reductions in resting, nonresting, and total energy expenditure are of similar magnitude. Both in the presence as well as in the absence of obesity, weight loss decreases visceral adipose tissue and liver fat, increases insulin sensitivity in skeletal muscle (insulin-mediated whole-body glucose disposal rate) and in adipose tissue (meal-induced or insulin-induced suppression of plasma free fatty acid concentration), and augments insulin clearance rate, without affecting pancreatic insulin secretion. These effects are of similar magnitude in participants with and without obesity and result in reductions in fasting plasma glucose and insulin concentrations. These data suggest that the same degree of calorie restriction and the same amount of weight loss have multiple beneficial effects on health outcomes in individuals without obesity, similar to those observed in individuals with obesity. 

OUP accepted manuscript

http://manuscript.elsevier.com/S0149291822001527/pdf/S0149291822001527.pdf

Food as Medicine for Obesity Treatment and Management.

The metabolic syndrome (MetS) comprises cardiometabolic risk factors frequently found in individuals with obesity. Guidelines to prevent or reverse MetS suggest limiting fat intake, however, lowering carbohydrate intake has gained attention too. The aim for this review was to determine to what extent either weight loss, reduction in caloric intake, or changes in macronutrient intake contribute to improvement in markers of MetS in persons with obesity without cardiometabolic disease. A meta-analysis was performed across a spectrum of studies applying low-carbohydrate (LC) and low-fat (LF) diets. PubMed searches yielded 17 articles describing 12 separate intervention studies assessing changes in MetS markers of persons with obesity assigned to LC (<40% energy from carbohydrates) or LF (<30% energy from fat) diets. Both diets could lead to weight loss and improve markers of MetS. Meta-regression revealed that weight loss most efficaciously reduced fasting glucose levels independent of macronutrient intake at the end of the study. Actual carbohydrate intake and actual fat intake at the end of the study, but not the percent changes in intake of these macronutrients, improved diastolic blood pressure and circulating triglyceride levels, without an effect of weight loss. The homeostatic model assessment of insulin resistance improved with both diets, whereas high-density lipoprotein cholesterol only improved in the LC diet, both irrespective of aforementioned factors. Remarkably, changes in caloric intake did not play a primary role in altering MetS markers. Taken together, these data suggest that, beyond the general effects of the LC and LF diet categories to improve MetS markers, there are also specific roles for weight loss, LC and HF intake, but not reduced caloric intake, that improve markers of MetS irrespective of diet categorization. On the basis of the results from this meta-analysis, guidelines to prevent MetS may need to be re-evaluated.

Anouk E M Willems

Papers

Effects of macronutrient intake in obesity: A meta-analysis of low-carbohydrate and low-fat diets on markers of the metabolic syndrome