Good question. This is different for every person. It depends on their activity level, diet, medical issues, hormonal levels, age, the type of training they are engaged at and overall health history. Yes, as we grow older we lose some lean mass, but when you combine all of the factors together then you get a better picture of how all these will affect the body fat %. I know people who got leaner as they grew older and others who gained more fat. People who stay active into their later year age much better than those who don’t. I have trained clients into their 70s and they were in great shape. They were able to enjoy a lot more in life than some of their friends and their overall health was great. I think what’s important is not so much how lean or what their body fat % is as they grow older, but rather how healthy they are and if they can still do activities like they used to when they were younger (up to a point of course, depending on their age).