Just to be sure here - because 16 grams for a 21 inch snake sounds way, way thin - can you please weigh something of a known weight (maybe a bag of food that has a marked weight on it) and confirm your scale is reading correctly. Also are you using the "tare" button to make sure the scale is properly reading zero including whatever container you weigh her in (or the tub your digital scale may have come) before you place her in there?

Do you mind me asking what source you got this snake from - breeder? hobbyist? pet store? reptile show? reptile rescue organization?

Here's a great link to help you understand the complete shed process.....

http://www.ball-pythons.net/forums/s...ad.php?t=28794

Here's a link to help you help your snake should it retain shed (don't do this stuff until your snake has tried to shed naturally itself).....

http://www.ball-pythons.net/forums/s...ad.php?t=74290