Hi Liza,
Ketosis is not something you can physically see, it is a process that takes place inside the body. To put it simply it is when your body starts to burn it's own fat reserves. This state (ketosis) is a dieters friend as once you enter into it, you won't feel any hunger, and may experience a sense of well being!
Carbohydrate you eat that doesn't get used through activity, gets stored as glycogen around the liver. It usually takes about 3 days for the glycogen stores to be burnt off, which is when you get to ketosis!
You can test for ketones in the body by buying sticks which you wee on! You don't have to buy the testing sticks though, a good indicater of ketosis is bad breath!!