People often ask: so how much should my cat weigh? And this is not an easy question to answer because it depends on what cat you have. Some breeds are very large, and therefore heavier - for example Maine Coons. An average domestic moggy should weigh between 8 and 10 pounds. To find the perfect weight for your cat, take her to the vet and get him to calculate her optimal weight. If your cat is 15% over her ideal weight she counts as obese; at 30% above, grossly obese. The classification after that is morbidly obese, which means that your cat is about to be killed by 'kindness'. The most obvious indicator of obesity is the amount of subcutaneous (just under the skin) fat. As a cat gains weight, her face appears to puff out and her neck develops a fold or two, rather like a human double chin. Her stomach will also become somewhat distended and sag like a pouch. A good test is to place both hands under your cat's belly and feel the ribcage. If you cannot feel each rib without pressing, then it's time to think about diets.
What causes obesity in cats?
In a small percentage of cats there may be an underlying pathology, metabolic problems, such as a thyroid dysfunction. It is therefore crucial that an overweight cat is checked by the vet especially if you add up the calories, and see no reason why your cat should be putting on the pounds.
However, in most cases, cats are overweight because they eat too much. A cat, like any human, will puts on weight by consuming more calories than she burns for energy. In the USA it is estimated that 40% of the cats are obese. (The figure is less for British cats, manily because many more of these spend time outdoors.) But does obesity actually matter? Are there any serious health risks for obese cats? The simple answer is yes. That's why this number is alarming.
Obesity is associated with arthritis, heart and liver disease (Hepatic Lipidosis), respiratory difficulties, heat intolerance, diabetes and impaired immunity to infectious diseases - for a start. Obese cats have shorter, more unhealthy lives.
Since with the vast majority of cats there is no underlying health problem, as responsible owners we have to ask ourselves what we are doing to make our cats fat, and try to correct it.
A cat's balanced diet
The ideal diet for a cat is high in protein and low in carbohydrates. For example, a mouse. From the nutritional point of view, mice are perfect, consisting mostly of protein and fat. The rest is water and minerals with plenty of roughage and only 3 to 8% carbohydrates. True carnivores such as cats do not need carbohydrates in their diet. What is more, they are actually poorly equipped when it comes to digesting carbohydrates. One reason is that cats lack amylase, an enzyme present in human saliva which breaks down starch. As a result, undigested carbohydrates turn into fat instead of being burned for energy.
Secondly cats require a lot of protein in their diet. Ideally 35-45% of solid food matter should be protein. This is much higher than for humans or dogs. This is because cats are not able to synthesise many important amino-acids (building blocks of proteins), which means that they have to get these proteins from external sources. An example of this is taurine, but this amino-acid is not the only one. L-carnitine, for example, is important in burning stored fat reserves and allowing the liver to convert fat back into glucose. Although L-carnitine can be synthesized from lysine and methonine, both of these are essential amino acids for cats (essential amino-acids are these which are not naturally made in the body). The best source of natural carnitine is red meat and dairy products with beef having the highest level.
So when choosing cat food think Atkins diet - lots of proteins and few carbohydrates and no excess calories. In fact feline nutritional experts have put this into a philosophy of cat nutrition, known (appropriately enough) as the 'catkins diet'. This means keeping the cat's diet as true to its carnivorous heritage as possible without decimating local small wildlife. Avoid those surplus calories. Dry food is where the most dangerous calories are. Most dry cat foods contain lots of carbohydrates which are essential to give consistency to the dry pellets. Except for high quality dry foods, the level of meat protein is sub-optimal. Finally, dry food is often left freely available, so the cat can nibble during the day when the humans are not around - all the more dangerous, as this is when the cat might eat out of sheer boredom.
If the cat has free access to dry food make sure that the amount in the food bowl does not exceed the amount needed for daily calorie intake. It is a good idea to add wet food to the cat's diet. When using treats, make sure that the treats are part of the daily calorie intake rather than an addition to the spare tyre around your cat's waist.
Weight loss diets
Getting an obese cat to lose weight needs to be done gradually and carefully. Never give your cat a crash diet. Cats have a unique metabolic response and they are not very efficient in processing of fat. So if an obese cat is put on a crash diet there is a serious danger that it will get Hepatic Lipidosis (a deposit of fat in the liver which reduces liver function). Also if the cat cannot get sufficient energy from its diet or fat stores (and the fat stores only release their energy gradually), it will start breaking up its own muscle cells.
If your cat is seriously obese you should discuss diet options with the vet. There are special low calorie diets available for cats. But always make sure you introduce any new diet gradually.
Remove treats from the cat's diet. If you want to give your cat an occasional treat, it is better to give her a small piece of chicken or fish. Cat treats available in the shops are designed to be palatable, but they contain a lot of carbohydrates with a substantial amount of sugar.
It is very important to get your cat doing as much exercise as possible, especially if it is an indoor cat. An obese cat may not want to participate at first, but once her weight goes down she will become more active. Over-feeding a cat is not a sign of love. It means that you put feeling good about yourself above your cat's welfare!