Table 1.

Studies excluded after full text review.

Author	Year	Title	Subjects	Reasons of Exclusion
Amer et al.	2017	Consumption of whey in combination with dairy medium-chain fatty acids (MCFAs) may reduce lipid storage due to urinary loss of tricarboxylic acid cycle intermediates and increased rates of MCFAs oxidation	52 abdominally overweight participants	The work analyses the metabolomics profile of patients subjected to different types of diet without distinguishing between patients with metabolic syndrome (or other traits of the latter) and healthy patients
Boden et al.	2015	Excessive caloric intake acutely causes oxidative stress, GLUT4 carbonylation, and insulin resistance in healthy men	3 subjects normal weight (BMI 23.0, 23.9, and 24.9) and 3 overweight (BMI 26.8, 28.7, and 28.1)	The study is not using a metabolomics approach to identify compounds
Chen et al.	2018	Serum metabolomics model and its metabolic characteristics in patients with different syndromes of dyslipidemia based on nuclear magnetic resonance	60 dyslipidemia patients (30 patients with SKYD and 30 patients with PDR) and 20 healthy subjects	Despite the study using a metabolomics approach, exclusively analyses patients with secondary dyslipidemia in SKYD (Spleen and Kidney Yang Deficiency) and PDR (Phlegm-Dampness Retention)
Chen et al.	2019	Trimethylamine N-Oxide Binds and Activates PERK to Promote Metabolic Dysfunction	Mouse model and cell culture	The study is not using a metabolomics approach to identify compounds; The study was not conducted on humans
Grün et al.	2018	High-Density Lipoprotein Reduction Differentially Modulates to Classical and Nonclassical Monocyte Subpopulations in Metabolic Syndrome Patients and in LPS-Stimulated Primary Human Monocytes In Vitro	86 women and men between 20 and 60 years old	The study analyses the differences in monocyte subpopulations in patients with metabolic syndrome using flow cytometry (absence of a metabolomics approach)
Heidenreich et al.	2017	Retinol saturase coordinates liver metabolism by regulating ChREBP activity	Mouse model and cell culture	The study was not conducted on humans
Kempinska et al.	2019	The Association between SOCS11656G>A Polymorphism, Insulin Resistance and Obesity in Nonalcoholic Fatty Liver Disease (NAFLD) Patients	138 patients with features of NAFLD 1000 controls	The study analyses the presence of genetic polymorphisms associated with metabolic syndrome and insulin resistance without using a metabolomics approach for the identification of metabolites
Kozyra et al.	2018	Human hepatic 3D spheroids as a model for steatosis and insulin resistance	Human hepatocyte 3D spheroid cultures	Study conducted on primary human hepatocyte 3D spheroid cultures
Leboucher et al.	2019	The translational regulator FMRP controls lipid and glucose metabolism in mice and humans	25 fragile X patients and 29 sex- and age-matched healthy subjects	The study analyses exclusively people with fragile X syndrome to assess how the absence of specific genes may influence the metabolic homeostasis; No metabolomics approaches were used
Silvestri et al.	2015	Two non-psychoactive cannabinoids reduce intracellular lipid levels and inhibit hepatosteatosis	Mouse model and cell culture	The study was not conducted on humans
Teslovich et al.	2018	Identification of seven novel loci associated with amino acid levels using single-variant and gene-based tests in 8545 Finnish men from the METSIM study	8545 non-diabetic men of mean age 57.3 ± 7.1 years	The study identifies genetic variants related to amino acid alterations in patients with metabolic syndrome
Zimmermann et al.	2010	Alterations in lipid, carbohydrate, and iron metabolism in patients with non-alcoholic steatohepatitis (NASH) and metabolic syndrome	37 patients with metabolic syndrome (25 NASH and 12 non-NASH) 37 controls	The study is not using a metabolomics approach to identify compounds