In 86 women with weight loss, there were significant changes in HOMA-IR (− 13.8%), insulin (− 11.2%), alanine aminotransferase (− 8.0%), VF (− 7.0%), AF (− 5.4%), TF (− 4.7%), GF (− 2.8%) and LM (− 1.5%), whereas irisin and HDL-C levels and the mean IPAQ score did not change. Here, FNDC5 is linked to atrial fibrillation.