Once again, the love of my life took to asking me weird questions. This time, the question is: how many cats does it take to eat a human?

Well, a hell of a lot.

How much does a cat eat?

As I was researching this part of the question, it became apparent that it would be much easier were the question to be reversed. While it is very easy to figure out appropriate amounts of white meat, red meat - just about any kind of meat, really - for a human of just about any age, there are very little confirmable and verifiable information on cats.

How much should a cat eat?

Long story short - we probably won’t be able to ascertain how much a cat can eat. Besides, if my two cats are any indication, they can eat just about any amount of food, then ask for more. There’s hardly any information on how much a cat should eat - at least weight-wise. During my search I did, however, find an article in the Pets section of WebMD, which - while I find WebMD dubious at best - trumps the self-proclaimed veterinarian practicioners so common on, say, Yahoo! Answers. Not to mention said article is not ridden with flamewars, which also counts.

According to the article, a cat should eat between 24 and 35 calories per pound of weight. I’m not crazy about the imperial scale in this answer, but Wolfram|Alpha can be used to convert calories per pound to calories per kilogram. Using that we figure out that a cat should eat roughly 52.91 to 77.16 calories per kilogram of body weight.

How much does an average cat weigh?

According to this article, an average cat will weigh between 4.5 and 5.5 kilograms. There are of course extremely large breeds, such as Maine Coon cats, which will reach as much as 8 kilograms, and there are tiny breeds like Russian Blue which weigh around 3 kilograms. I did some additional research, and I’d say it’s safe to assume that our average cat will weigh 5 kilograms.

Speaking of assumptions…

As long as we’re assuming that our average cat weighs 5 kilograms, let’s assume some more things. For the purpose of further calculations I will assume that the weight of the food ingested is of no concern to a cat (of which I believe I’ve seen proof on my very own floor). I will also assume that a cat eats as much as it should and then stops eating (about which I’ve seen some scientific discussion and some flamewars). For the sake of the poor cats I will also assume that our human-devouring horde of fluffy felines has an entire day to do it’s task.

How much is there to eat on a human?

Now it’s getting morbid. I’m finally starting to enjoy myself here. And it seems that I’m not the only one, since there are a couple of answers to this question on Quora. I am somehow not surprised at all. It is also much easier to find the nutritional contents of semen than the aforementioned Quora answers, which I find hilarious.

The general consensus seems to be that there’s about 70% of usable - I mean, edible - meat in a human body. Most people who calculate that seem to do so through analogy to a pig, which has about 70% of edible meat in it’s body. I suppose that human flesh is not called “long pork” for nothing, so let’s roll with it.

How much does an average human weigh?

Thankfully, this is easier to find out than the purrfect mass for a feline. BMC Public Health hosts an article on average human weight per region. It’s a short and sweet read which I recommend tremendously. In the meantime, however, seeing as I’m hailing from Europe, I’m going to assume that our average human due for an untimely death by a horde of cats weighs 70.8 kilograms.

Working from that, we can calculate that there’s about

$$ 70% \cdot 70.8kg = 49.56kg $$

of edible meat on a human, assuming that our killer kitties don’t enjoy eating guts. I wouldn’t enjoy that, so let’s assume they don’t either.

How many calories are there in a human?

According to this post, pork - which I’m going to use as a reference here, since I can’t get a hold of a butcher who can tell me how many calories are there in a medium fat cut of human - has a high point of 227 calories per 100 grams and a low point of 105 calories per 100 grams, which would place us between roughly 1050 and 2270 calories depending on the cut. If we take another assumption and average this out, it comes out to 1660 calories per kilogram, and that is what we’re going to use.

Using the mass of edible meat on a human we calculated before, we arrive at $$49.56kg \cdot 1660 \frac{calories}{kg} = 82269.6\ calories$$ Now we’re getting somewhere.

Tying it all together

Now, as we’ve calculated previously, our average at weighs 5 kilograms and should consume an average of 65.035 calories per kilogram of body mass, which works out to 325.175 calories per cat per day. And this isn’t great news, either - you see that number we’ve calculated a while back, for the amount of calories in a human? That number which is two orders of magnitude larger…?

Yeah. So our final answer is $$\frac{82269.6 calories}{325.175 \frac{calories}{cat \cdot day}} = 253.0009 cat \cdot day$$ So 253 cats, one slightly hungrier than the average, can deal with the edible portion of the human body in a day. Even if we assume that they’re all very hungry and eat the maximum of what a cat should - 77.16 calories per kilogram, so 385.8 calories a cat - it would still take roughly 214 cats.

In conclusion - cats suck at getting rid of bodies, unless you are a crazy cat lady (or otherwise have access to a hell of a lot of cats). And even then, you’re left with the dirty work to do yourself - the bones, hair, nails, guts and all the other unpleasant things aren’t going to dispose of themselves.

Just make sure you don’t use a metal bathtub full of lye.