Weight Loss in Cats

By: Mary Newell Sanders, DVM

TVMA Member
Bellville, TX

Published December 2015

Why Lose Weight?

Weight loss is tough. More than 50 percent of cats in the U.S. are overweight, and odds are your cat could stand to lose a pound or two (or 10). Overweight cats tend to live shorter lives than their more fit counterparts. Even a few extra pounds puts your cat at significant risk for a number of serious health problems, like diabetes, heart disease, high blood pressure and arthritis. Because obese cats tend to lie around more and are generally less active, owners often mistake the early signs of disease such as lethargy and decreased activity for “normal laziness.” By the time the cat is actually seen by a veterinarian, he or she is very sick. Losing weight and getting into shape will add years to your cat’s life and is not as hard as you think.

How Do I Know If and How Much Weight My Cat Needs to Lose?

Determining an ideal weight for your cat can be difficult. In fact, most owners are unable to identify obesity in their pets. What is actually ideal, most owners think is too thin. Just as in people, frame size differs from cat to cat, and weight loss should be based on body condition, not just the number on the scale. There are a number of reputable websites that can help you determine your cat’s current and ideal body condition and weight:



How Do I Get My Cat to Lose Weight?

The basic premise behind any weight loss plan is calorie reduction and increased exercise. However, cats in general, and especially obese cats, have special physiologic needs that you must take into consideration. Cats can develop a serious, sometimes life-threatening form of liver disease called hepatic lipidosis if they do not eat for as little as two or three days. Therefore, you should always consult with a veterinarian prior to starting any kind of diet or weight loss plan for your cat.

Once your veterinarian has examined your cat and determined that he or she is otherwise healthy, you will need to determine your cat’s ideal weight. Once you know how much your cat should weigh, you can calculate how many calories your cat will need to eat daily to lose weight. The basic formula for weight loss in cats is below:

  • Resting Energy Requirements (RER) in kcal/day = 30 (ideal weight in kilograms) +70
  • Ideal weight in pounds divided by 2.2 = ideal weight in kilograms
  • The “average” 10-pound cat needs approximately 200 kcal/day for weight maintenance.
  • Number of calories needed to lose weight = RER x 0.8
  • Example Calculation for a 15-pound cat who should weigh 10 pounds:
  • 10 pounds/2.2 = 4.5 kilograms (ideal weight in kilograms)
  • RER = 30 x 4.5 + 70 = 206 kcal/day
  • RER x 0.8 = 206 kcal/day x 0.8 = 165 kcal/day needed for weight loss

Depending on how overweight your cat is, you may find that the calculated calorie intake for his or her ideal weight is too drastic a reduction. In this case, calculate your energy requirements based on a target weight, have your cat weighed again in 30 days and reassess weight loss goals at that time.

What Do I Feed My Cat?

Many owners are surprised how much their cat is actually supposed to eat in a day and find they are grossly overfeeding. Make sure you are measuring or weighing your cat’s food so you know exactly how much you are feeding. Be sure to feed your cat meals, and do not leave food out all the time, as free feeding promotes obesity. Offer a high-protein, low-carbohydrate canned diet. Cats are obligate carnivores, meaning their diets are based on protein—not vegetables, fats or carbohydrates. To make dry food into a kibble, the manufacturer has to add carbohydrates and, thus, extra calories. Many cats will lose weight simply by transitioning to a canned diet and fed in measured, meal feedings.

How Do I Transition My Cat to a New Diet?

You should never abruptly change your cat’s diet as this can result in vomiting, diarrhea and/or lack of appetite. Transition your cat from his or her old diet to the new one slowly, over the course of a week or two. Start by adding small amounts of the new diet to the old one, and increase the amount of new food while decreasing the amount of old food daily. If your cat stops eating or develops any vomiting or diarrhea while transitioning to the new diet, call your veterinarian before continuing any further.

How Do I Get My Cat to Exercise?

Increasing your cat’s aerobic activity can be difficult. Cats evolved as stalkers, meaning they chase their prey in short, anaerobic bursts that burn little energy. Since taking your cat on a long walk is not an option, owners have to get creative about encouraging their cats to move. The easiest way to get your cat to move around more is to frequently move his or her food bowl. Move the bowl daily from room or room or upstairs to downstairs. Keep the food bowl as far away from your cat’s favorite spots as possible. Grab your cat’s attention with toys that move or make noise, including laser pointers or feathers on a string. Engage him or her for 10 to 15 minutes a couple of times a day. If your cat can go outside safely, encourage him or her to do so; nature is full of fun things to chase!

How Do I Know Whether My Cat is Losing Weight?

It is important to check your cat’s weight once a month to know if the weight loss plan is working. You should expect your cat to lose about a pound a month. Every cat is unique; thus, there is no one approach that will work for every cat. Be willing to make adjustments as needed. Work closely with your veterinarian to ensure your cat stays safe and healthy while you work toward your cat’s ideal weight. Remember your ultimate goal is a longer, healthier life for your pet, and your commitment to your cat’s weight loss is the key to his or her success.

Dr. Mary Newell Sanders practices at Marek Veterinary Clinics in Bellville and Sealy, Texas.

One Response

  1. My car is a Rescue Cat & about 11-12 yrs old
    She has been fixed after having a litter oe 2, according to vet I took her to right away when I got her. Found she had a chip so know her weight is vorrect. She was thin with droopy tummy & weighed 8 lbs. She now weighs 13 lbs & will ONLY dry food, PERIOD. She gets a total of 2/3 of cup per day, most of which she sleeps. Runs thru house at nite before I go to bed… will not touch chicken, albacore tuna, NOTHING but dry… that has no fillers or grain. Hervtreats consist of 6-10 pieces out of her 2/3 cup of dry kibble, not actually formal Treats
    She has drunk MUCH water from time I got her so I thot about Diabetes & she was tested at local vet &.no diabetes. She goes outside several times per day in summer but not long in winter. Seems healthy other than weight. She comes inside to use litter box & does not want to use any other place… so the water she drinks so much of IS obvious when litter is cleaned daily!!! I owned 2 sister cats that lived to be 22&23 but never had problems.

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