my cat is skinny at the back end of her body?

hello, I have another question about my cat. she is perfectly healthy and eating fine, but she gets skinny around the back end of her body sometimes? is this a problem or is it ok? I attached a photo  

Hello!  Is your cat registered at a vet surgery?  Ideally, your vet will weigh your cat every year when they are vaccinated and at any appointments, so they will be able to check for you if there are any overall downward trends.  You don't say how old your cat is;  young cats can go through 'skinny' and more normal phases as they grow into their frame while still putting on weight, but particularly after reaching adulthood this can be concerning.   For example there is an illness, hyperthyroidism, in which cats eat exceptionally well and are very active but lose weight, because their thyroid gland - which controls the speed at which food is converted to energy - starts working overtime.   Liver disease and even diabetes can sometimes present this way.  It's definitely worth a quick chat to your vet in case they think that blood tests may be merited.

hello, thanks for the quick response! sorry I left out her age, she is 1 year and 8 months old. I think she is like that today because we bought a different type of cat food, which she doesnt like and doesnt eat much of it. I really hope she doesnt have an issue, as she is the sweetest cat Ive had, and she is still very young.  

sorry left out more details, she is registered at a cat only clinic, she had her annual check up and vaccines back in January this year, the vet said she was perfectly healthy and doing very well.

Ah, bless her!  I hear owners say this quite commonly, but cats are unlikely to turn their nose up at food on grounds of taste preference, when their bodies are hungry enough that they are actively losing weight because of it.   Usually in this scenario there is something else going on, be it low level nausea from pancreatitis or liver disease, or something else.   Some cats are naturally tiny, but it spunds as thpugh your cat is smaller than you think she should be, so we would still reccommend a check up.