What causes weight loss in cats, especially if they are still eating and drinking normally? If the weight loss is more than 10% of a feline pet’s body weight, it is a question worth finding answers to. In this piece, we will take a look at various cat losing weight scenarios, the explanations for each, and the solutions.
How can you tell that your cat is below her normal weight?
- The ribs are easily felt with light pressure.
- The pinching behind the ribs is far more obvious.
- Muscle mass is obviously diminished and not well defined.
Cat Losing Weight but Eating and Drinking Normally
The first thing you may suspect is cat diabetes. Although this health condition does make cats drink and eat more but still lose weight, it is not the only culprit. The following can also cause similar symptoms:
- Thyroid hyperactivity Also known as hyperthyroidism, this condition can increase your pet’s metabolism, thus burning more calories than usual. This makes your cat constantly hungry whilst still maintaining or losing some weight. Your pet may also be more vocal and active.What to do: After ruling out other causes like parasites, food quality, and current physical condition, take your cat to the veterinarian for an examination.
- Kidney disease The extreme thirst manifests first before the feline’s appetite goes down. Then your furry friend will begin to lose weight. The abnormal thirst is due to the kidneys being unable to filter blood and the urine becoming concentrated.What to do: Bring your pet to the veterinarian for tests to confirm the cause.
- Liver disease Some forms of liver ailments can trigger unusual thirst levels and loss of weight in cats.What to do: Observe other symptoms to rule out other possible causes. Take your feline pet to a veterinarian for proper diagnosis and treatment.
- Roundworm infestation Parasites take all the nutrition from the food your cat is ingesting even before it is absorbed in her body. As such, your cat may eat and eat but never feel full. She will then lose weight, although this may not be obvious. The worms will cause swelling, making your pet look rather fat.What to do: If your cat displays a swollen abdomen, unusual poop, lethargy, and vomiting (with visible worms), bring her to the veterinarian. Humans can catch roundworms in cats, so immediate treatment is necessary.
- Ageing According to veterinarian Dr. Glenn Ericson, pets tend to lose weight as they get older even though their appetite is still good.What to do: If the weight loss is less than 10% of her body weight and is not accompanied by other symptoms, no worries. Otherwise, take your cat to the veterinarian.
- Low-nutrition food Poor-quality feline food can keep your pet from feeling satisfied with her meals. She may eat much but get hungry easily, which is comparable to humans eating junk food.What to do: Try to offer canned food or those that are nutritious and have more protein content.
Cat Losing Weight and Hair
- Hyperthyroidism In addition to what has been mentioned above, this illness can cause patchy hair loss in cats.What to do: Once all other possible minor causes are ruled out and the issue still persists, visit your veterinarian.
- Cancer Some of the symptoms of this condition are vomiting, low appetite, diarrhoea, and sometimes hair loss.What to do: See your cat’s veterinarian for the right diagnosis and medication.
- Heart disease This is a likely cause if the hair loss is accompanied by weight loss, shortness of breath, and coughing.What to do: Bring your little friend to the veterinarian for a check.
- Low-quality diet As mentioned, lack of nutrients can affect your cat’s coat health and make her lose weight too.What to do: Provide nutritious food, especially those containing vitamin C.
- Allergies If your feline friend is allergic to certain food, she is likely to lose some hair and weight. The same is the case with a flea or mite infestation. These pests can trigger extreme itchiness, leading to hair loss in some areas of your cat’s body. Dermatitis, which is a symptom of allergies, involves itchiness and rashes leading to hair loss.What to do: You can do DIY skin-soothing solutions using herbs (e.g., aloe vera gel or rosemary dips). With food allergies, simply withhold any food that causes reactions in your pet. If you wish to be on the safe side, bring your furry pal for a check-up with the veterinarian.
Cat Losing Weight in Hindquarters

If your cat’s hind legs look bonier than the rest of her body, it may be a sign of an overactive thyroid. If your pet drinks and eats more, is more restless, has a fast heart rate, and vomits, she likely has hyperthyroidism.What to do: Take your pet to the veterinarian for proper medical advice and attention.
Cat Losing Weight and Throwing Up
These possible causes have been discussed above. They are as follows:
- Intestinal parasites
- Food allergies
- Gastrointestinal allergies and infections
- Inflammatory bowel disease
- Hyperthyroidism
- Kidney disease
- Cancer
What to do: Check for other symptoms and see whether they are of the minor causes. Otherwise, bring your feline buddy to the veterinary clinic for a proper check.
Cat Losing Weight and Not Eating
- Picky habits Some cats have been known not to eat or drink from a slightly clean bowl or stale food and water.What to do: Ensure the bowls are spotlessly clean, and the food and water fresh when serving them. Store the food in airtight containers to preserve its taste. You can also consider changing the location of the feeding area. Do not put it too close to the litter tray, bathroom, or some other area undesirable for your cat.
- Changes in diet Sudden changes in the kind of food you offer to your furry friend can result in a feline snub. The meal may be not as appealing or is not as nutritious.What to do: If you are changing your pet’s diet, do it gradually over a span of a week or more, depending on your cat’s response. You can also consider going back to providing the original food.
- Unfavourable environment Cats are sensitive and can be stressed by changes in their environment. Changes to the feeding schedule, moving to a new house, a new housemate, or your prolonged absence can trigger a feline fast.What to do: See to it that your feline’s mealtimes are constant and not interrupted by other people or animals. If you are going away, have someone familiar to watch over your pet. If the fasting duration is more than a day or two, call your veterinarian.
- Gastrointestinal issues Allergies, parasites, and bowel issues can take away your pet’s appetite and lead to weight loss.What to do: Check for other related symptoms. If the culprit is food allergy, shift to other safer food options. Otherwise, have your cat’s veterinarian do a thorough check to be on the safe side.
- Ageing
Old Cat Losing Weight
Is it normal for cats to lose weight as they age? As mentioned, it is fairly common amongst senior cats. However, if your ageing pet’s appetite has lessened and her weight is decreasing, check for the following:
- Stress
- Heart disease
- Hyperthyroidism
- GI (gastrointestinal) upset
- Respiratory illness
- Kidney disease
- Cancer
What to do: Narrow down the causes, starting with the minor ones. Take your pet to the veterinarian if weight loss is more than 10% of her body weight and there are other worrying symptoms.
Did you find the answer to your feline weight loss question? Discover more pet care tips on our cat blog!