It is fairly difficult to get an accurate reading on normal human scales because a bun weighs so comparatively little. Plus your own scales are obviously not calibrated like the vet’s scales are. I dont know if you could perhaps borrow scales from someone or buy one? It doesnt have to be anything fancy or expensive. I put my bun in a bowl and weigh him on digital kitchen scales. It’s safest to do it on the floor in case the bun decides to get the h out of Dodge, so to speak.

If she actually has lost all that weight, she would’ve had to be quite obese to begin with for it to be a normal effect of stopping alfalfa pellets. Have your vet said anything about her being  overweight?

Do you have pictures?

Here is a web site with pictues that illustrates varous degrees of normal body shape vs obesity or skinniness in a rabbit:

http://www.therabbithouse.com/diet/rabbit-weight.asp

While it’s true there can be variability in weight between vet’s scales and home scales, I’ve never experienced it to be that much weight… usually it’s on the order of ounces difference.

She looks noticeable thinner now, and just from the photo I would consider that to be underweight.  Looks like she lost 1.6-ish lbs, about 37% of her body weight from the post-spay weight. Unless you had her on a diet that was aimed at getting her to lose weight, I would take her in to the vet soon to see what’s going on.

I agree with Dana, she has lost a lot of weight and unplanned substantial weight loss should always be investigated, both in humans and animals.

Several things could be the cause. Your vet will probably want to do bloodwork. Bloodwork is a very good diagnostic tool.

Agree with Bam, could be a number of things and bloodwork is usually the first step.

I agree, she looks noticeably thinner. I would have the vet check her teeth and do blood work. They may also want a poop sample to test for internal parasites.