EffectsofPopularDietsonAnthropometricand CardiometabolicParameters:AnUmbrellaReview ofMeta-AnalysesofRandomizedControlledTrials

Abstract

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 metaanalysesofrandomizedcontrolledtrialsthatexaminedtheeffectsofdifferentdietsonanthropometricparametersandcardiometabolicriskfactors. Strength and validity of the evidence were assessed through a set of predefined criteria. Eighty articles reporting 495 unique meta-analyses were examined,coveringawiderangeofpopulardiets:low-carbohydrate(n=21articles),high-protein(n=8),low-fat(n=9),paleolithic(n=2),lowglycemic-index/load(n=12),intermittentenergyrestriction(n=6),Mediterranean(n=11),Nordic(n=2),vegetarian(n=9),DietaryApproaches 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 evidenceofanimprovementinweightandbloodpressurewasalsoreportedfortheDASHdiet.Low-carbohydrate,high-protein,low-fat,andlowglycemic-index/loaddietsshowedsuggestiveand/orweakevidenceofareductioninweightandBMI,butcontrastingevidenceforlipid,glycemic, and blood pressure parameters, suggesting potential risks of unfavorable effects. Evidence for paleolithic, intermittent energy restriction, Nordic, vegetarian, andportfoliodietarypatterns was gradedas weak. Amongall the dietsevaluated, the Mediterraneandiet had the strongestand most consistentevidenceofabeneficialeffectonbothanthropometricparametersandcardiometabolicriskfactors.