Fattening Up A Cat – How To Help A Cat Gain Weight


Fattening up a cat

How do I fatten up an underweight cat?

Now to answer the question, firstly of course it is important to determine if the cat has an underlying medical condition which has caused him or her to be underweight. Once the cause has been diagnosed and addressed, the appetite should return in most cases.

The goal is to stimulate the cat’s appetite and/or increase calories. Below are some ways to help fatten up a cat.

Tips to fatten up a cat

  • Switch to kitten food, which is higher in calories.
  • Feed smaller portions frequently throughout the day.
  • Add some grated cheese or plain yoghurt to the top of the cat’s food.
  • Canned food is more appetising than dry. 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.


Causes of weight loss in cats: 

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 (anorexia)
  • Stress, fussiness, inter-cat issues
  • Weight loss despite a healthy appetite and no underlying sickness (not enough food, nursing queen and loss of muscle mass as the cat ages)
  • Weight loss due to a medical condition but not related to loss of appetite (hyperthyroidism, inflammatory bowel disease, acromegaly)

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

  • Hyperthyroidism – Caused by a benign hormone secreting tumour of the thyroid gland which causes the metabolism to speed up.
  • Diabetes – A common endocrine disease where the cells build up a resistance to insulin, a hormone necessary for glucose to enter the cells. As a result, glucose levels build up in the bloodstream
  • Chronic kidney disease – A gradual loss of kidney function over a period of months of years which causes a build-up of toxins in the blood. Senior cats are very prone to developing kidney disease.
  • 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.
  • 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 – A mouth ulcer (or mouth sore) is a painful, open sore which can affect the gums and tongue.
  • 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 pathogens 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.


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.

The veterinarian may want to perform additional tests which can include x-rays, ultrasound, and additional blood work such as T4 tests to evaluate for hyperthyroidism.


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