Waistline (UPDATED)

Question
Thanks. Right now, my waistline is just over 28 inches, but I just ate. Lately, it has been between 27.5 and 28.5 inches, and is over 29 inches when I sit down. Is this too much?
-------------------------------------------
The text above is a follow-up to ...

-----Question-----
I was wondering if you could tell me what the average waistline measurement was for a 13 year old male with a height of 5 foot 3.  Mine, up until a month ago was 25.5 to 26 inches, and I had a firm stomach and well defined abs. In the past month, though, I have noticed that some excess fat has begun to collect on my belly, and you can no longer see my abs.  Last time I went to the doctor, about two months ago, I was actually on the slightly slimmer side of the weight charts, but I'm not sure if I still am (I don't have a scale available.)  I don't think I am overweight, but in addition to my belly fat, my butt, which used to be perfectly firm, has gotten so that it jiggles when I walk. Again, not a lot of fat there, but more than I had a month ago, so I was wondering what you thought. I have not grown in the past few months otherwise.
-----Answer-----
If your definition has lessened, it's because your activity (exercise) has been reduced and/or because you're taking in more calories than your body uses.

Probably a bit of both things are happening.

There is no 'set' waist measurement since a higher muscle mass may result in a larger measurement (picture any body builder).  In fact, the weight charts and BMI charts don't apply at all to people who are exceptionally fit or atheletes.  They all register as "overweight" according to the basic charts.

For an average muscle mass and build, a 5'3" male with a waistline under 28" is about right.

Find out more about calculating ideal size here
http://www.sandowmuseum.com/ideal.html

Find out how to eat right and be healthy here
 http://www.GetTheReal.info  

Answer
I think you're just fine except for measuring your waist far too much :)
 No one counts a measurement while sitting down - so forget that one. A measurement usually taken after being awake for 30-60 minutes, but before eating/drinking anything would be most accurate (everyone tends to bloat a little while sleeping).  

1. Prev:losing eight pounds by February
2. Next:fighting anorexia