Do Cats Gain Weight After Being Spayed? Vet-Reviewed Facts

Most prospective cat owners look forward to having their cat spayed or neutered. After all, tom cats and queens are significantly more annoying and cause a lot more trouble for their owners than spayed and neutered cats. However, most cat owners are also concerned about the prospective weight gain common in cats who are reproductively altered. To learn more about spayed cats and weight gain, read on!

The answer is complicated, but cats that have been spayed or neutered seem to eat more, so you may want to avoid free-feeding for a few months after the procedure to avoid weight gain.

Will My Cat Gain Weight After Being Spayed?

There is no conclusive evidence to support that a cat’s energy threshold will always decline after sterilization. In practice, though, it is worth treating the situation as though it does, as there is also no evidence that a cat’s energy threshold doesn’t decline. As a result, veterinarians will consider whether a cat is spayed or not when determining its Maintenance Energy Requirements (MER).

MER is determined by taking a cat’s Resting Energy Requirement (RER)—in the case of an adult cat weighing about 10 pounds, around 218 kcal per day—and then applying multipliers to it based on their energy levels and physical status. It’s a unique identifier, and no two individuals are the same.

Details About MER

The multiplier for a spayed cat is 1.2, while an intact cat will get a multiplier of 1.4. So, a spayed cat will have an MER of approximately 261 kcal/day for spayed cats and 305 kcal/day for intact ones.

However, even if spayed or neutered cats have fewer energy requirements, this doesn’t mean that weight gain is inevitable. You can take agency over your cat’s health by not allowing them unlimited access to food.

A study performed on spayed and neutered cats shows that both male and female cats ate significantly more post-surgery than before. There’s no known answer to why this occurs; we just know it does.

Given how easily cats gain weight after being spayed or neutered, it’s safe to say that their resting energy requirements don’t change. So, the increase in food intake likely has to do with a hormonal or other biochemical change after sterilization. If you take certain medications, you suddenly constantly become hungry and gain weight.

The study on female cats showed that spayed kittens ate significantly more four weeks after the surgery—well after the point of healing—and that the effect peaked 10 weeks after the procedure. At 18 weeks post-surgery, spayed and non-spayed cats were eating similar amounts of food. However, the study on male cats showed a dramatic increase in appetite during the first week post-surgery, with bodyweight increases of 10%.

Free-Feeding vs. Meal Times

While these studies have differing details, the conclusions are essentially the same; altered cats eat more than reproductively-intact cats. Thus, portion control is significant for neutered cats to prevent them from gaining too much weight.

Veterinarians generally consider meal feeding more appropriate for cats than free-feeding for most of their lives. Still, even if you’d prefer to free-feed your cat, it’s best to restrict their food intake for 4–5 months post-surgery to help prevent weight gain. As long as your cat gets proper nutrition, there’s no need to overfeed them.

Final Thoughts

There are a lot of differing opinions on the causes of rapid weight gain in spayed and neutered cats, but one thing is for sure: all other variables controlled, cats who are spayed or neutered generally eat more than ones who aren’t. Not free-feeding your cat in the immediate months following their procedure can help prevent them from getting fat in the long run.

Featured Image Credit: Bogdan Sonjachnyj, Shutterstock