How Weight Loss for Cats is Done Properly

Obesity is a growing problem for both pets and people. Weight loss for cats is a bit trickier than with dogs or people in that it needs to be done almost at the speed of paint drying. Yep, that’s right. Make kitty lose too much weight too fast and they can get very sick and die quickly.

Overweight pets have many of  the same health issues obese people do: joint pain, decreased mobility, extra stress on the heart, increased risk of diabetes, difficulty breathing. Plus they are not able to reach their rear end to clean it so urine burns and irritates their skin (cat urine is acidic).

The first thing you need to be aware of is that if your cat is fat, it is most likely NOT due to an underactive thyroid. Hypothyroidism is very common among older women and dogs, but it is pretty rare in cats.

Cats frequently do however develop hyperthyroidism which is common in older cats. Usually when this happens you  will notice that your cat is getting skinny even while they have a ravenous appetite.

They may be howling at night or seeking out cooler places in the home, i.e. sleeping on tile floors instead of on carpet or a soft bed.

If a senior cat suddenly has the energy level of a kitten, that is not a good sign.

Weight loss for cats can be a good thing if they need to lose weight, but if they were not overweight to begin with or are getting skinnier despite eating lots of food, something internal is going on- it’s time to see your vet!

Diagnostic tests along with a physical exam can rule out the major conditions: dental problems, diabetes, hyperthyroidism, kidney disease, and gastrointestinal disorders.

What if my cat is Big Boned?

The average normal body weight of cats (8-12 pounds) is true for the majority of domestic cats but does not cover breed discrepancies. Just like there are differences in the bone structure of breeds of dogs (the size of a toy breed vs. a Great Dane), there are in cats too, although not as dramatic.

The smallest breed of purebred cats I know of is the Singapura, which will be about 5 pounds as a fully grown adult. Some other tiny breeds include the Burmese, Tonkinese, Devon Rex, and Persian/Himalayan.

Naturally lean breeds include the Cornish Rex, wedge-head Siamese, Balinese, Oriental & Color point shorthairs, and Abyssinian.

The largest breed is the Maine Coon, which can be about 18 pounds fully grown (and also prone to hip dysplasia just like large breed dogs ;).  People will sometimes allow this breed to gain too much weight because they think since their cat is ‘supposed to be a really big cat’ that it’s okay.

There are rumors that Ragdolls are ‘supposed to be huge’ for some reason. I don’t get it. They are not.

Most Ragdolls I’ve seen, and I’ve probably met more in person than most people have, are 8-14 pounds and have a body frame similar to the average cat.

All of these types of cats are just as prone to weight gain as any other cat. Not every purebred cat will adhere to the breed standard, either. I have seen many very small Ragdolls, Siberians and Maine Coons.

I have seen a Devon Rex that resembled an engorged tick at 10 pounds and recently I saw another Devon Rex that weighed 16 1/2 pounds! That breed is not meant to be that large! That is fat, not muscle!

I do get to see a variety of these guys up close and personal working at a cats-only vet clinic so breeds are fun for me to talk about. You can check out photos and descriptions of interesting breeds at the Cat Fancier’s Association site.

Non-purebreds can really vary in their size as well, simply due to genetics. Females generally have smaller body frames than males.

How do you tell if they are big boned? You want to look at the size of the head, the size of the paws, and the length of the body- not just the overall size of the cat. A larger framed cat will always have a larger head and larger paws.

How To Make A Cat Lose Weight

This is where it gets challenging because we have to be careful- we do not want a cat to lose weight too quickly because  when that happens all of their excess fat goes straight into their liver and clogs it up so it cannot perform its basic functions.

Then you have a jaundiced cat that can quickly be a dead cat aka hepatic lipidosis.

Secondly, if a cat does not like the food you are offering, they will literally starve themselves to death (cats are notorious for being the pickiest eaters EVER!) so you need to have a few different options on hand. See my post on baby food here.

It really is as simple as calories in vs. calories out. There are a few reasons why cat parents may not realize how much they are actually feeding.

  1. Many brands of pet food simply do not disclose the calorie count anywhere on the package. They also are not required to list it on their website. Don’t hesitate to contact the manufacturer, as they are legally required to put their contact information (address & phone number) on the food label. Most companies will have an email address or contact form on their website.
  2. Feeding the recommended amount on the food label seems logical, but it is not the right thing to do. Most companies will tell you to feed more than you should so that you go through their product faster and you end up purchasing more food overall.
  3. Lots of people own multiple cats, or even a combination of dogs and cats. Typically these people do not want to separate them during meal times- that is the excuse I hear the most often “I have more than one cat so it’s hard, poor me….”.

Miss Emilie Rose

Miss Emilie Rose (pictured above) was overweight when I adopted her from the shelter, and I had a second cat too.

Guess what worked? I completely separated them during feeding times (about 15-30 minutes twice daily), and measured out proper portions for each, and voilà! She lost the excess weight easily.

Remember that fat cats are usually food motivated, which means that you can train them. At first it is a bit of work to get all of your pets separated, but they learn quickly where they get fed and then it becomes more routine over time.

How Much Should I Feed?

Here is the equation I used to calculate how much to feed each of my two adult indoor cats, courtesy of Dr. Lisa Pierson at the ultimate online cat food authority: (13.6 x ideal lean body weight in pounds) + 70 = calories to feed. This is a general guideline and will be a little more than your what cat actually needs.

How To Calculate Calories


According to this equation, I should be feeding my cats each 219.6 calories per day, but they are actually getting 175-195 calories per day and stay very close to their ideal weights-they have never been too skinny and have a little extra padding so I know that is plenty of calories.

You’ll know if you’re overfeeding if your cat either does not lose weight or gains weight. Gaining weight on a diet is not allowed. They should slowly lose at a rate of 1-2 % of their body weight each week.

As for their ideal weight, most cats fit into the 8-12 pound range. Cats with larger body frames can be around 14-15 pounds.

The first goal is to get them under 15 pounds so that they can reach around and clean their own butts so you don’t have to, then after that keep going until they reach their ideal weight.

Cats tend to begin putting on extra weight after being spayed or neutered, so that is a perfect time to ask your vet how much you should be feeding.

In addition to the number of calories, cats thrive on a low carbohydrate/high protein/moderate fat canned or raw diet so take this into consideration when choosing foods. Rad Cat makes a great raw food-check out my review here.


Baby scale

Baby (pediatric) scales work well for weighing cats and are similar to what veterinarians use. You can purchase one like this on Amazon.

You Will Need:

  • A baby scale that weighs in pounds and ounces. If you cannot afford one, your vet should allow you to bring your cat in regularly just to get weighed. Do weekly weigh ins! They should lose at most 1-2% of their body weight per week, no more than that. Two ounces per week or half a pound per month is just fine.
  • The equations to calculate how much to feed [(13.6 x ideal weight in pounds) + 70] and the minimum number of calories your cat needs to eat per day to avoid hepatic lipidosis (15  calories per pound of lean body weight per day)  Most cats need 150-250 calories per day for maintenance, and usually under 200 for weight loss.
  • Choose what food(s) you are going to feed remembering it must be something your cat likes, and then calculate how much to feed based on how many calories per day your cat needs, and how many calories per ounce (or per can, or per cup) that food has. Each flavor and brand will be different, since ingredients can really vary between brands. Also, certain meats are fattier than others. For example, rabbit is a very low-fat protein, and some brands will add another type of animal fat to their rabbit formula, and some will not. I suggest following the recommendations on   She has also created a food chart with nutrition data from the most common brands for you.
  • NO TREATS! This is a vice people have for their pets and themselves- I really don’t know why. Think of yourself when you are on a diet. If you let yourself have several treats everyday, does that help you lose weight? No. Your cat will survive without treats just like children can survive without being given cookies everyday.
  • All humans in the house must be aware of the diet plan- ideally just one person should to be in charge of feeding the cat (to avoid accidentally giving your kitty double the meals).  Also you may have to separate multiple pets, meaning you may have to move the dog’s food so the fat cat cannot steal it, put the skinny cat’s food high up on a counter or table if the fat cat cannot jump, etc. Use dog/baby gates if you have to-they work.

An open can of cat food will last for up to 7 days in the refrigerator as long as it is covered.

You can buy plastic covers at any pet store for around $1-2, but vet clinics get them for free from the pet food companies- all you have to do is ask for one! You can also use tin foil to cover it or put it in a Ziploc bag.

Then when you take the cold can of food out of the fridge, transfer the portion you’ll be feeding onto a microwave safe dish (do not microwave metal cans or glass baby food jars) and nuke it for 5-10 seconds to get the chill out.

Many cats will flat-out refuse to eat food that is too cold.

Use a calendar for your fat cat(s) to write down their weight every week to help track their progress. Any kind of calendar will work.

You can even print free calendar pages from Google Images (just enter the month and year you want in the search box, i.e. January 2016, then click on ‘image results’ and copy & paste into a Word document, then print).

You can bring these with you to your cat’s next wellness exam and impress your vet!

You’re ready to roll!

Remember that vet techs are trained to help pets lose weight so if you have questions about your cat’s individual situation, never hesitate to contact your vet’s office with questions.

If you have gotten your cat to successfully lose weight, let me know in the comments below!


One comment

  1. Anita says:

    Well it is always hard for me to tell when my cat is under/overweight unless the doctor tells me so. Am guessing from your article my current cat is a big bone.
    I know someone who has a Maine coons and he is overweight and every time someone mentions this they blame the cat breed, the cat is 30 pounds. I should show them this article so they can do something about their cat weight.

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