ladypunk123
While each snake is different, like us humans having their own metabolism, you must also remember that generally snakes are innately opportunistic eaters. Thus some snakes will eat more than they should if given the chance.
While you do not want to under feed your snake, it is even worse to over feed your snake. A slightly underfed snake is not going to have health problems. An over weight snake can have health effects on the heart and liver which may cause their life to be shortened. As well once a snake is over weight it is often very difficult to get the excess weight off of them.
A good way to judge your snakes weight is to look at their body structure. A healthy snake should look like a loaf of bread. The bottom of the body(under belly) being the main part of the loaf and the rest of the body(dorsal part) looking like the rounded top of the loaf.
A snake that is to thin resembles a triangle, a spinal ridge along the back and the sides draping downward toward the under belly.
A snake that is to fat has two main indicators, tube sausage looking, round everywhere, no flat belly and hips. Hips are when the area just before the cloaca bulges out to the sides.
Hope this helps.