Sir,
I was referring to the same thing as you. You say your animal is at least 3 years old. That animal should be nearly full grown by that time, and full grown is not 20 inches to vent. I am referring to the SAME thing as you (SVL) ok. But what should and what is are very different because each person who keeps any reptile has different ways of going about doing things.
"Should" should constitute a generally accepted method or perhaps outline for keeping these lizards. In that generally accepted method we speak of choice of temps, from cool, to very very hot. Choice of humidity, food to match or exceed energy output, and a well sized enclosure. You have yet in two posts to provide that information, I would suggest you do so, so that others can be of better HELP to YOU.
Keep in mind, this issue is not from a weekend or a week that he was not fed correctly. I say this because if he was kept in decent conditions he could go a week no problem without eating. It is as a direct result of the way you have been keeping him.
Post your conditions for people to see, cage size, temperatures, humidity, feeding info, surface temperatures (basking spot). That is the only way you will get some very useful information.
Goodluck,
Mike.