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Fattening Up A Cat

How do I fatten up an underweight cat?

Now to answer the question, firstly of course if there is an underlying sickness contributing to a loss of appetite that needs to be addressed (we will look at that further down the article). If that is fixed, the appetite should return. Basically, you want to stimulate your cat's appetite (if he's stopped eating) and/or increase calories. Below are some ways to help fatten up a cat.

  • Switch to kitten food, which is higher in calories.
  • Feed smaller portions but more often.
  • Add some grated cheese or plain yoghurt to the top of your cat's food.
  • Canned food is more appetising than dry food. I recommend canned 3-4 times a day while you are trying to increase his weight as well as leaving dry food out for your cat to nibble on between meals.
  • If canned food isn't an option, consider putting him on a home prepared diet, at least for the short term, this may be raw or cooked. Include muscle meat, as well as chopped heart, liver, and kidneys. Foods which are highly appealing to cats include cooked chicken breast cut into pieces, minced beef or chicken, tuna, and liver. Tuna and liver are fine to give to a cat who has lost his appetite, but they should not be given for more than a day or two as they can cause medical issues.
  • Heating up your cat's food to body temperature can be enough to increase his appetite as warmer food tends to produce a stronger smell.
  • Feed a high-quality brand of food, the cheaper brands have more fillers which really don't offer your cat a lot in the way of nutrition.
  • Speak to your veterinarian about specific brands of food to help gain weight in cats. Hills a/d comes in dry and canned form, is high in calories and digestible proteins.
  • If your cat has a poor appetite, try syringe feeding him a highly palatable form of wet food.
  • Give your cat some milk. Most cats are intolerant to cow's milk, but most supermarkets sell milk designed for cats to drink.
  • Speak to your veterinarian about nutritional supplements such as Nutrical or Nutri-Stat that can get extra calories in and help to kick start your cat's appetite.
  • If you have several cats, feed the underweight one in a separate room to ensure he gets enough food. Sometimes more dominant cats can hog the food bowl.

Why is my cat losing weight?

Cats lose weight for a number of reasons and diet alone is just one small cause. Before we go into ways to help fatten up your cat, it is important to determine if there is an underlying cause. Weight loss can be loosely divided into the following categories:

  • Sickness resulting in a loss of appetite
  • Loss of appetite due to other factors (fussiness, stress etc)
  • Weight loss despite a healthy appetite and no underlying sickness (not enough food, nursing queen, age-related it is common for cats to lose muscle mass as they age)
  • Weight loss due to a medical condition but not related to loss of appetite (hyperthyroidism, IBD to name two)

Medical causes are seen most commonly in middle-aged to senior cats, the majority of which cause your cat to lose weight due to a poor appetite. Hyperthyroidism, on the other hand, speeds up your cat's metabolism, so despite a normal to increased appetite, your cat continues to lose weight. 

The most common causes in middle-aged to senior cats include:

  • Hyperthyroidism - Caused by a benign tumour of the thyroid gland which causes the metabolism to speed up.
  • Diabetes -
  • Kidney disease - Senior cats are very prone to developing kidney disease. As the kidneys fail, toxins begin to build up in the cat's system, causing him to feel unwell and lose his appetite.
  • Cancer - There are many types of cancer which can develop in cats, most cancers will cause your cat to feel unwell, which in turn leads to anorexia and weight loss. Cancers can develop in the cat's mouth, creating discomfort when he eats.

Other causes of weight loss include:

  • Parasitic worms - Cats are prone to several types of parasitic worms, tapeworm is the most common cause of weight loss in cats due to the worm competing with the cat for food.
  • Nursing kittens - A lactating queen (mother cat) uses enormous resources to provide nourishment to her kittens, which over time can lead to her losing weight.
  • Mouth ulcers
  • Cryptosporidium and giardia - Parasitic infections caused by single-celled protozoa resulting in vomiting and diarrhea.
  • Ecoli - A bacterial infection of the intestinal tract leading to vomiting and diarrhea.
  • Inflammatory bowel disease - A leading cause of vomiting and diarrhea in cats, IBD is a group of disorders caused by the infiltration of inflammatory cells in the intestinal tract resulting in poor digestion and absorption of food.
  • Cat flu - There are several types of pathogen which can cause flu in cats, symptoms typically affect the upper respiratory tract which can result in a loss of appetite as they lose their sense of smell.
  • Stress - Cats are very sensitive to changes in routine, household, bullying from other cats.

This list is by no means extensive, there are many other medical causes. Read here for more causes of weight loss in cats.

How is the cause of weight loss diagnosed?

Many of the above conditions will also have additional side effects, which can give your veterinarian an indicator as to what the problem is.

Your veterinarian will perform a complete physical examination of your cat and obtain a medical history from you. He will want to perform some baseline tests to check the overall health of your cat. These will include a biochemical profile, urinalysis and a complete blood count. Depending on his index of suspicion, he may want to perform additional tests such as x-rays, ultrasound, and additional bloodwork.