This varies from person to person. From the perspective of human science, it takes at least 3-6 months to see the effect of fitness. Usually we will see changes around 1 month. It takes 3 months to stabilize the muscles you grow. You should know that human stomach cells are updated once every 7 days, human skin cells are updated once every 28 days, and liver cells are updated once every 0/80 days. 98% of cells in the human body need a year to be updated. It takes a long seven years for bone cells to renew.