Background and Aim: Activation of brown adipose tissue can be a new approach in reducing obesity and related complications. The aim of the current study was to investigate the effect of high intensity interval training (HIIT) supplemented with L-Arginine (L-Arg) .on serum levels of fibroblast growth factor 21 (FGF21) and atrial natriuretic peptide (ANP) in overweight and obese men.

Materials and Methods: In this semi experimental study, 40 overweight and obese men ( with mean age 24.58±6.52 years and mean body mass index 29.43±3.66 kg/m2) were selected through  purposive sampling method and were randomly divided into 4 equal groups of HIIT, supplementation with L-Arg, HIIT+ L-Arg ,and placebo. The training program consisted of 6 weeks of HIIT training (3 days.per week). L-Arg supplementation (6 gr/day) was taken orally. Blood sampling was done 24 hours before and 48 hours after intervention and the blood serum was used for the measurement of FGF21 and ANP levels. The obtained data was analyzed using ANOVA, ANCOVA and post -hoc Bonferroni tests at a significant level of P<0.05.

Results: It was found that the serum level of ANP significantly increased in L-Arg and HIIT+L-Arg groups (P values wwere 0.02 and 0.01, respectively), but HIIT did not cause a significant change in the level of ANP. The serum level of FGF21 had no significant changes after HIIT and use of L-Arg.

Conclusion: It seems that L-Arg supplementation and HIIT together with L-Arg supplementation with increased level of ANP can be considered as an effective step to activate brown adipose tissue.