Mother cat is losing weight

Question
My cat just had four kittens. Before she became pregnant she was at a health weight, but now three weeks after the birth she has lost a lot of weight. Is this due to nursing?
She is so thin and I have been giving her tuna and milk once a day trying to help her regain some weight.
What should I do?

Answer
Hi Jeanette, how are her bowel movements?? Are you only feeding her tuna and milk.. or is this just a supplement with her regular food?? Milk is not the best thing for cats to eat and if she has diarrhea from it this can cause weight loss. Is she eating lots?? or just picking at her food?
Moms often can look quite thin when they have kittens, but this is more noticeable when the kittens are closer to 5 and 6 weeks old when they are just draining her and haven't' started eating on their own yet
Please write me back and I will try to give you a more accurate answer. Teresa