i have also been told, depending on the sex of the snake, the 800-1200 gram rage is their "Terrible teen" phase. They tend to go off food for very few reasons and are generally just a nuisance.

My biggest girl did this for me last year. She was teetering just on the edge of 1000 grams and ALL of the sudden she refused food. I offered less frequently and tried a bunch of tricks but nothing worked. After 5 months she decided food was awesome again and now eats with gusto. Over the 5 month period, she lost maybe 130 grams. I'd have to check my records for the exact numbers. She'd take the occasional mouse or super small prey item. Or a live hopper or 4. (over a few days). But now shes back to eating F/T small rats.

Have you tried pre-scenting?