Obesity is associated with low-grade inflammation in adipose tissue (AT) and dysfunctional adipocytes producing inflammatory molecules. A recent study reveals profound MAIT cell abnormalities in patients harboring metabolic disorders, suggesting their potential role in these pathologies. Now the inventors show that MAIT cells induce adipose tissue and ileum dysfunction and inflammation in obese mice. Moreover, the inventors show that a treatment with an agent capable of inhibiting the activation of MAIT cells (i.e. Ac-6-FP) during high fat diet (HFD) improved metabolic parameters and in particular insulin sensitivity. Thus the present invention relates to the use of an agent capable of inhibiting the activation of MAIT cells for the treatment of obesity and obesity-related disorders.