**5. Conclusions**

High adherence to MD can have a positive impact on all parameters of MetS. In addition, there is sufficient evidence suggesting that long-term consumption of MD can protect from obesity and improve cardiometabolic risk markers, including the markers used for the diagnosis of MetS. Although high heterogeneity was identified across the included studies, our results support previous findings and point to the potential biases that may derive from the use of MDSs. Furthermore, it remains still unclear whether MD exerts the same beneficial effect on both unhealthy and healthy populations; therefore, further research is needed in this field.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/ 10.3390/nu13051514/s1, Supplementary File S1: MOOSE checklist, Supplementary File S2: Search Strategy, Supplementary File S3: Quality of Studies according to the New Castle Ottawa Scale, Supplementary Figure S1a–e: Funnel plots of studies included in our meta-analysis regarding each parameter of MetS, Supplementary Figure S2: Subgroup analysis based on the quality of studies regarding WC, Supplementary Figure S3: Subgroup analysis based on the quality of studies

regarding HDL cholesterol, Supplementary Figure S4: Subgroup analysis based on the quality of studies regarding serum TG, Supplementary Figure S5: Subgroup analysis based on the quality of studies regarding FBG Supplementary Figure S6: Subgroup analysis based on the quality of studies regarding SBP.

**Author Contributions:** Conceptualization: L.C., D.R.B., E.K. and M.C.; methodology: X.T.; software: X.T.; validation: L.C., D.R.B. and E.K.; formal analysis: X.T.; investigation: L.C., D.R.B. and E.K.; data curation: L.C., D.R.B. and E.K.; writing—original draft preparation: L.C., D.R.B. and E.K.; writing— review and editing: L.C., D.R.B., E.K., X.T. and M.C.; visualization: X.T.; supervision, M.C.; project administration, M.C.; All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Not Applicable.

**Informed Consent Statement:** Not Applicable.

**Data Availability Statement:** Not Applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
