Diet and age are major factors in muscle gain and fat loss. I’m a 45yo male and have to work 5 times harder than 20 somethings to gain muscle and lose fat. when I was 20 something, I was ripped and didn’t have to work hard to get that way and keep it. Then life happened and couldn’t keep lifting and maintaining cadio and other workouts even as much as I did. Now I’m a balding 45yo with a size 38 gut and skinny arms and have been lifting cadio at least 4 to 5 days a week for 6 months. Older equals muscle loss and harder work to couteract it.