How to Fatten Up a Cat? Find Out Why Your Kitty May Be Thin

Our quick take: To help a thin cat gain weight, first find out why she is thin. Any unexplained weight loss needs a vet visit, because hyperthyroidism, diabetes, kidney disease, dental pain and worms are common causes. Once those are ruled out, feed a calorie-dense, high-protein food (kitten food or a vet recovery diet), offer several small meals a day, warm wet food slightly to boost its smell, and weigh your cat every week or two. A cat that has not eaten for more than a day or two needs a vet right away, because cats that stop eating can develop a dangerous liver condition called hepatic lipidosis.

Cat too thin? Are you trying to find ways on how to fatten up a cat?

If you are in need of a way to fatten up a cat, you have a rather rare problem. Many times, people can't get their cat to stop eating! So start by working out why your cat needs to put on weight.

If you've recently taken in an underfed stray, several small meals enhanced with vitamin supplements will slowly but surely get him up to ideal weight.

Otherwise, you may have to find out what exactly is making Kitty lose weight and solve that problem first.

Remember: this is a cat, not a heavyweight boxer. You have plenty of time to gradually put on the pounds.

Why Your Cat is Thin

First of all, you have to identify why you need to get your cat fattened up. (It will be kindly assumed you don't want to eat the cat.) Did your cat have a litter of kittens recently? She may be burning calories just feeding her babies.

Does he share his food dish with other cats? He might be getting bullied out of his fair share. Does she go outside often?

She may have a parasite inside her that's digesting her food or maybe she lost a tooth in a scuffle. Is your cat elderly? Could be either a disease or just loss of appetite.

Very young cats will burn calories easily. A cat that's depressed or stressed out might just not be in the mood to eat. Always consult a veterinarian before making drastic changes to your cat's diet.

Hyperthyroidism

This is a common problem in middle-aged and older cats. In about 98% of cases it is caused by a benign growth (adenoma) in the thyroid gland that makes too much thyroid hormone (thyroxine), which speeds up the metabolism. Many hyperthyroid cats lose weight even though they seem hungrier than ever (Cornell Feline Health Center). The good news is that it is very treatable with daily medication, a prescription iodine-restricted diet, radioactive iodine therapy or surgery.

This will make it hard for your cat to keep weight on. Your veterinarian will need to run a blood test to determine if it is hyperthyroidism, diabetes or another cause.

Worms

Your veterinarian may prescribe something or you can use an over-the-counter pill depending on the severity of the situation.

Spending more calories than in taking

Kittens and adolescent cats have a lot of energy that they can burn off just running and playing. Don't discourage Kitty from exploring her world or honing her abilities with healthy exercise.

Just feed her kitten chow, which is formulated to be higher in protein and fat content than adult cat food.

Why should you fatten up a cat?

No one likes to see poor, skinny kitty cats wasting away! Like any living being, a cat needs to eat and digest food to live.

If a cat is not eating or at least doesn't seem to be getting nourishment from food, you need to find out what's wrong.

How to Fatten up a cat?

1. High Protein Cat Kibble

As mentioned before, you may want to try food formulated specifically for kittens as that has the most fat and protein. Your vet may also suggest a prescription high-calorie recovery diet. For product ideas, see our guide to the best cat food for weight gain. Read that label! Look for a named animal protein, such as chicken, turkey or fish, near the top of the list. A named meat meal (for example “chicken meal”) is a concentrated protein source and is fine; vague terms like “meat by-products” tell you less about what is inside.

2. Canned Cat Food

Maybe your cat doesn't care for the texture of dry food. Or maybe mouth pain or lost teeth is her reason for being reluctant to eat. Consider canned cat food. Wet food smells stronger and is soft, so it tempts many reluctant eaters. Gram for gram it has fewer calories than dry food because it is mostly water, so you may need to feed more of it, mix wet and dry, or ask your vet about a high-calorie wet recovery food.

Read the label again. You want to know what all is in the food and how many calories, so you know how much your cat is really getting each day.

3. Try Some Pantry Items

Generally, you are discouraged from giving a cat people food, but desperate times may call for desperate measures. Don't feed your cat any foods that will only make the condition worse.

A small amount of plain, unsweetened yogurt on top of the food adds calories and entices Kitty to eat more.

Canned sardines and mackerel are acceptable if packed in water rather than oil with no salt. Both yogurt and sardines have calcium and yogurt has probiotics. They're also both foods cats are fond of.

4. Offering treats throughout the day or in between meals

Treats should not be used for meal replacement as they are not very nutritious though they are high in calories. A few treats between meals can whet your cat's appetite though.

A few treats at a time will help your cat's weight slowly increase. Small portions served often may be what's needed.

5. A Little Home Cooking Can Be Helpful

One simple method to get Kitty to eat is to heat up her food just a little. This will intensify the smell, making it more appetizing to your cat. You may also want to try making her some eggs.

Scrambled eggs will be easier for her to eat. Just make sure the eggs are fully cooked. As said before, this is not a boxer, so no raw eggs.

Raw eggs contain avidin that makes it hard for her to absorb vitamin B plus there's the possibility of salmonella. Skip the salt, pepper and butter as these are not very good for your cat.

Eggs are high in the fat and protein your cat needs to put on some healthy weight. A bit of thoroughly cooked tuna or liver might help things along, but keep this small and infrequent (too much liver can give a cat too much vitamin A).

There are other methods depending on the situation. A sick cat or one that refuses food may need assisted feeding or an appetite stimulant from your vet, such as mirtazapine (sold as Mirataz, an ointment rubbed on the inside of the ear) or capromorelin (sold as Elura, for cats with kidney disease), both FDA-approved to manage unwanted weight loss in cats. Don't syringe-feed without your vet's guidance, because a cat can inhale food. A cat that's being bullied out of his share by other cats may need to be fed separately.

A nursing mother just needs more food to help her replenish. Intestinal parasites can be dealt with by administering a few pills. In any case, talk with and cooperate with your veterinarian to find out which solution is best for your cat.

Final Say

Helping a cat gain weight isn’t about simply feeding more—it’s about understanding why they’re underweight and supporting them with the right nutrition, care and environment.

By choosing calorie-dense foods, offering frequent small meals, reducing stress, and addressing any medical issues, most cats can reach a healthier weight safely. Every cat gains weight at a different pace, so patience and consistency matter.

And if your cat still isn’t improving or shows any signs of illness, a veterinarian’s guidance is essential. With the right approach, you can help your cat feel stronger, healthier and happier.

Sources

• Feline Hyperthyroidism, Cornell University College of Veterinary Medicine
• Information about FDA-approved drugs for cats (Mirataz and Elura), U.S. Food and Drug Administration
• FDA approves appetite stimulant for cats, Cornell Feline Health Center