I personaly prefer to feed boas small meals more often as apposed to larger less frequent meals. I've got 6' females that eat 1 and occasionally 2 medium rats every week. At her size I would probably use either smalls or even large pups weekly. As has been stated boas have slow metabloisms, but they also have huge apitights so it's really easy to over feed them. She's been on mice up till now and she's looks about perfect as far as body wieght goes. Remember rats are far higher in fat then mice. Just feed her a relatively small meal weekly and moniter her weight. If she looks thin up her food a little, if she starts getting chubby back it off. She should always have a square muscular body shape. Far to many bread loaded shaped boas out there.