This study was performed in the two subparts, study 1 and study 2, to investigate the effect of changes in intensity and type of exercise held after fasting on FGF21/Akt Pathway and metabolic variables.The purpose of the study 1 was to investigate changes of AMPK-FGF21 signaling from a combined treatment of aerobic exercise and fasting by showing acute effects of aerobic exercise, which is given in the different intensities after fasting, on AMPK/FGF21 signaling in rats' skeletal muscles and to provide baseline data on safe and effective treatment methods to improve metabolic disorder. Total 36 male Sprague-Dawley rats (8 weeks) were randomly divided into 6 groups (n=36); A low-intensity aerobic exercise group after 24hr-fasting (n=6), a high-intensity aerobic exercise group after 24hr-fasting (n=6), a low-intensity aerobic exercise group after 18hr-fasting (n=6), a high-intensity aerobic exercise group after 18hr-fasting (n=6), a high-intensity aerobic exercise group (n=6) and a control group (ad libitum, Control; n=6). Soleus muscle tissues were harvested after each fasting and exercise. Western blotting was performed with the harvested soleus muscles and their p-AMPK, PGC-1α, PPARα, and FGF21 protein were analyzed. The results showed that longer fasting time and stronger exercise caused more active AMPK-FGF21 signaling. Also, low-intensity aerobic exercise after 18 hrs of fasting activated AMPK-FGF21 signaling more than high-intensity aerobic exercise. This result suggests that low-intensity aerobic exercise after 18hrs fasting is safe and effective as an alternative exercise treatment to improve metabolic disorder.The purpose of the study 2 was to investigate the effect of different types of exercise, provided with low-intensity aerobic exercise after fasting, on improving metabolic disorder by showing long-term effectiveness of various types of exercise on FGF21/Akt pathway and metabolic variables in obesity-induced rats and to provide baseline data on safe and effective treatment method for improving metabolic disorder. Total 40 male Sprague-Dawley rats (4 weeks) were induced into obesity through 6 weeks of high-fat diet and then they were randomly divided into 5 groups (n=40); A low-intensity exercise group after 18hrs fasting (n=8), a low-intensity resistance exercise group after 18hrs fasting (n=8), a low-intensity combined exercise group after 18hrs fasting (n=8), a 18hrs fasting group (n=8) and a control group (ad libitum, Control, n=8). The fasting time and exercise intensity were set up as 18hrs and low-intensity load based on the study 1 that confirmed 18hrs of fasting and low-intensity exercise were effective on AMPK-FGF21 protein expression. The aerobic exercise was performed 3 times/wk, and it consists of 4 weeks of the resistance exercise with climbing a ladder and the combined exercise with treadmill running and climbing a ladder. In the 18hr-fasting group, 18hrs of fasting was applied 3 times/wk whereas there was no special treatment such as fasting and exercise in the control group. During the experiment period, body weights were measured every week and during the 4 weeks of treatment period, 1RM was measured every week. On a day after 4 weeks of treatment, blood samples were taken from anesthetized experimental animals and changes in haematology (FGF21, adiponectin, β-hydroxybutyrate) were examined. Then, harvested tissues (soleus muscle, fat tissue around testicle) were weighed and wester blotting was performed to them to observe changes in protein (p-AMPK, PGC-1α, PPARα, FGF21, p-Akt, p-FoxO3a, IRS1, p-IRS1, GLUT4 in skeletal muscle and UCP-1 in white adipose tissue) and changes in muscle cross-sectional area and satellite cell through histological analysis. As a result, the positive effect of long-term exercise treatment after fasting on body composition was confirmed by weight and fat mass loss regardless of exercise type. Also the low-intensity exercise after fasting was effective on protein expressions of PGC-1α, FGF21, p-Akt, and GLUT4, and combined exercise after fasting was the most effective among the exercise type on protein expression of FGF21 in skeletal muscles, Akt, and GLUT4, and catalyzed expression of UCP-1 in white adipose tissue. In addition, the effect of combined exercise after fasting on metabolic disorder improvement by increasing blood adiponectin, FGF21 and β-hydroxybutyrate was proved, and it shows great metabolic advantages. Also, FGF21/Akt Pathway was investigated by combined exercise after fasting by verifying the high correlation between FGF21 and Akt protein in skeletal muscle. In summary, this study investigated the effect of exercise intensity and types after fasting on metabolic variables through FGF21/Akt Pathway in the study 1 and the study 2. This research suggests that the concurrent treatment of aerobic exercise after fasting, the resistance exercise after fasting and the combined exercise after fasting are effective in improvement of metabolic disorder and the concurrent treatment of combined exercise after fasting was the most effective method to provide metabolic advantages among these exercise types.