What's the purpose/value of a wet food diet for cats? Why would you want to do that?
Due to some recent health issues I've been highly focused on my cats diet, and regularly logging caloric/potassium/B12 intake as well as mass eaten per meal. One thing I noticed is that wet food has an extremely low calorie to mass ratio compared to dry food.
It seems nearly impossible to meet a cat's caloric intake requirements on wet food alone. For example, a 5.3 oz can of a certain brand of wet food contains only 62 kcal, meaning that a cat would have to eat a whopping 18-20 or so ounces of this stuff to get their daily intake in the 200 kcal area.
The four wet foods I have info on here range from 0.735 to 1.245 kcal/g, meaning 160-272g of food that must be consumed per day. That's on or past the upper limit of what I see healthy cats fit in their stomachs in one day (my 3 year old tops out around 200g if she absolutely stuffs herself, but typically eats 180g-190g, my older cat maxes out about 180g, but typically eats 150g-160g). By comparison, the dry food I have on hand is 4.103 kcal/g, meaning only 48g or so must be eaten.
Under the assumption that the nutritional content of wet vs dry food is similar and sufficient, I can't imagine a normal cat being able to eat enough wet food to get even close to their daily caloric intake. Both of my cats only get a disturbingly low 130-180 kcal/day when on wet food only.
So why does wet food exist? For what purpose would you feed your cat wet food? I used to view it as a reasonable alternative to dry food but since I began calorie counting and monitoring diets I can't see a reason to ever feed it to a cat.
The only value I can sort of see in it is if you want to do a wet/dry mix to maintain a healthy caloric intake but also add some mass to the food so the cats aren't walking around on empty stomachs, but I'm not sure if there's any real reason to do that. The other thing is, I wonder if I'm just selecting particularly low calorie wet foods (there seems to be a trend of lower-end cat foods containing higher calorie counts).
The brands I've examined are Royal Canin, Hill's, Wellness, Iams ProHealth, and various small but respectable brands. Currently I've settled on Royal Canin for both wet and dry.
(I don't buy the "wet foods help cats get water" line of reasoning so much. While they'll certainly get water from wet food, in my limited personal experience, in a sample of about 20 or so cats, I've never actually seen a normal, healthy cat severely dehydrate itself when water is available by not drinking it, and a pet fountain or better placement of a water bowl almost always solves issues there. When a cat isn't drinking water it's seems to virtually always be a sign of an actual bigger health issue. But, in any case, I'm interested in other value besides just water content, and I can't justify watery food with critically low caloric intake.)
