Metabolic syndrome continues to be highly prevalent and contributes to a rapidly growing problem globally. The most important therapeutic intervention is diet modification; an intervention that its efficacy has been proven in metabolic syndrome. Some studies have shown that low glycemic index diet has positive effects on patients with MetS. So, the goal of this study is to compare the effects of low Glycemic Index diet and metformin drug on MetS components in order to replace the drug by the diet in adults with MetS. This study is a Randomised Controlled Clinical Trial. The inclusion criteria are the age between 25 and 65 years old and having 3 characteristics related to metabolic syndrome according to the Adult Treatment Panel, not taking any drug that might affect blood pressure and glucose, insulin or lipid metabolism, not having diabetes, liver or kidney diseases. Patients will be excluded if they get gastrointestinal disorders or lose their interest to continue the study. The 60 patients will be randomly allocated to two groups of metformin drug and low Glycemic Index diet. The intervention period is 8 weeks and at the end of the trial, the groups will be compared regarding the following factors: weight , blood pressure , waist circumference, fasting blood sugar and lipid profiles (TG, total cholesterol, LDL, HDL).