The answer can be found in our attitude and behavior. The biggest problem is that we can tend to set up a routine of overfeeding. The cat’s owner enjoys feeding their cat because it makes his/her cat happy. People like to please their cats. So, if, for example, the person gives her cat some cooked chicken from the fridge, in time her cat will associate opening the fridge with getting chicken. Then her cat will actively ask her to open the fridge door and get the chicken. Then the owner will comply because she likes to please her cat. At that point the cat’s owner has become trained by her cat and overfeeding is established. The first reason is that a cat’s owner likes to feed her cat and is susceptible to being trained by her cat.
It is my firm belief that most cat owners do not make much of an effort to exercise their cats. That is not a criticism. It is just a fact. This is probably because cats like to sleep (and eat) and are quietly in the corner on the sofa or on the condo bed. Why disturb that routine of life. The second reason is because cat owners don’t exercise their cats enough.
It is also reasonable to presume that if a person is overweight they may have adjusted their personal standards as to what is a normal weight. This would result in the cat’s owner being unable to recognise that her cat is overweight. A slightly tubby cat might look normal to a lot of people. If you see healthy feral cats you see typical cat profiles. They are often considerably more rangy than domestic cats. The third reason is that some people don’t recognise what a overweight cat looks like.
Multi-cat households are a potential problem. Each cat probably has their own bowl but how do you keep one cat (the fat one) from eating from the bowls of other cats? It can be done but it is complicated. The modern person is probably unwilling to get involved in that sort of complication. The fourth reason is the difficulties in controlling the eating habits of a fat cat is mult-cat household.
A reasonable number of cats wander outside and become time share cats or visit other homes and get fed there as well. When this happens it is all but impossible to control a cat’s food intake and manage weight loss. The fifth reason is the wandering cat eating elsewhere and/or prey on wildlife.
Lastly and perhaps most importantly it can be difficult to precisely reduce a cat’s food intake over time. If a cat is eating too much you have to reduce food intake gradually to change the cat’s habits. That means adjusting downwards the amount of food provided. If a person buys canned cat food that can be difficult because it probably means wasting food. Wet food in pouches may also pose problems. Dry cat food comes in pellets and so it is easy to control. Some manufacturers provide a measuring cup for dry cat food. However, it is my contention that dry cat food can encourage a cat to eat too much because of its high carbohydrate content. Personally, I would not revert to a dry food diet to manage food quantities, easy though it is compared to wet food. The last reason is that a cat’s owner needs to carefully manage a cat’s food intake to reduce their cat’s weight and a lot of people are not committed enough to do this accurately.
Charlie, my three-legged cat cannot put on weight because it would severely restrict his mobility. My personal technique for him is tough love. If I have set up an overfeeding routine or if he has trained me to feed him at certain times (too often), I simply (and reluctantly) steel myself and refuse his request. I let him eat what is left. He eats this happily. Cats don’t hold grudges and are not upset by tough love.
Why is it hard to slim an overweight cat? Because we don’t exercise enough personal discipline in respect of food supply and in exercising our cats or even cat management generally.