Weight Reduction in Cats – General Information

Weight loss can be challenging for anyone – two- or four-legged! However, losing weight and getting in shape can add not only years to you or your pet’s life; it can also make those extra years more enjoyable. Helping your cat attain a healthy weight may be easier than you think. It simply requires understanding the need for weight loss and fitness, attention to details and guidance and assistance from your veterinary healthcare team. 

Why a Healthy Weight is Important for your Cat

As little as two pounds above your cat’s ideal weight can put it at risk for developing some serious medical conditions. Unfortunately, when a cat is overweight or has obesity it no longer it is at great risk for developing a secondary condition. Some of the common feline weight-related disorders include:

  • Type 2 diabetes – a cat with obesity is at least three times more likely to develop than serious disease as a cat of healthy weight

  • Kidney disease

  • Chronic inflammation

  • Heart disease

  • Osteoarthritis

  • High blood pressure

  • Many forms of cancer – especially intra-abdominal cancers

Further, overweight felines and cats with obesity are expected to live shorter lives than their normal weight counterparts. Cats with obesity tend to physically interact less with their families and are often less energetic and playful. We are just beginning to understand how serious and threatening extra adipose tissue can be for both humans and pets.

Start with Calories

For weight loss, the formulas seem simple enough: fewer calories in plus more calories out equals weight loss. Unfortunately, it’s not as simple as that formula. For starters, cats that are overweight or diagnosed with obesity must eat. Their physiology is different than humans or dogs and if they do not eat for as little as two consecutive days, they can develop a life-threatening form of liver disease known as hepatic lipidosis. Humans with obesity starting a diet program are also vulnerable to this serious condition. It is for this reason that you should never put your cat on a diet without the assistance of your veterinary healthcare team.

Let’s start by calculating the calories a typical cat needs. You’ll first need to have your cat examined by your veterinarian and an ideal or target weight calculated. The average domestic cat should weigh approximately eight to ten pounds. If your cat is 18 pounds, you can calculate its ideal weight to be 10 to 12 pounds. A basic formula for weight loss in cats is:

  • Ideal weight in pounds divided by 2.2 give you weight in kilograms (kg)

  • Calculate the Resting Energy Requirements (RER) based on this ideal weight

  • RER in kcal/day =

    • (ideal or target weight in kg)^0.75 x 70 or (ideal or target weight in kg to the ¾ power) x 70


    • [30 x (ideal or target body weight in kilograms)] + 70

  • For weight loss in cats multiply RER of target or ideal weight times 0.8

Ideal weight (lbs)

Calories to feed (kcal) at 80% RER per day







Note: This is a general guideline only and is not meant as a substitute from your veterinarian’s specific recommendations.

For many cats, the best way to feed will be by offering a canned diet food fed several times per day. It is vital that you closely monitor and record calories when starting a weight reduction program. Feeding too much will result in no weight loss and feeding too little can result in serious consequences such as hepatic lipidosis.

The Art of Changing Diet

When you are introducing a new diet to your cat, allow several days for the transition. In general, we recommend gradually adding the new diet over a one to two week period. Start by substituting one-quarter of the diet for two to three days, then increase to one-half total volume of food for another two to four days, then three-quarter new food for a final three to five days before completely switching to the new diet.

Creative Exercise

In an ideal world, we’d take a jog with our cats or enjoy a mile swim in the morning to stay fit. We certainly don’t live in that world! Getting cats to engage in slow, long-duration aerobic activity isn’t just difficult – it goes against their biology. Cats weren’t designed to function as scavengers and persistence hunters the way humans and dogs evolved. Instead, cats evolved as predators and stalkers who expended very little energy seeking their prey and seldom strayed far from their territory. When they came across prey, they burst into an intensely anaerobic and short-duration hunt. Most wild cats would pursue their prey at top speed for less than a minute. Once this activity was complete, they required hours to physiologically recover before their next hunt. If they missed several consecutive prey opportunities, they could be in serious danger of lacking the energy necessary to successfully hunt.

Our domestic cats are very similar to these wild felines. While our dogs may enjoy a brisk walk or jog, our cats aren’t designed for that sort of activity. Our cats prefer the hundred-yard dash to the marathon. Even more complicating is the fact that cats evolved on a diet based on protein as opposed to humans and dogs that can eat a wide variety of vegetables, proteins, and fats. Since cats are obligate carnivores, the same dietary rules don’t apply. Many cats will do better on a high protein, low carbohydrate diet for weight loss for this reason.

Just because cats aren’t good endurance athletes doesn’t mean we shouldn’t encourage physical activity. Some simple tips for getting your cat to move more are:

·      Play “Find the Food” - Move the food bowl upstairs or downstairs and rotate it so that the cat always has to walk to get to its food bowl. Cats are smart, and if the food bowl moves upstairs, they’ll start relocating upstairs, too.

·      Move the food bowl as far away from your cat’s favorite areas as possible.

·      Use feather toys, flashlights, boxes, paper bags or balls, anything that your cat finds interesting to chase. Try to engage your cat for ten minutes twice a day. You can do this while you eat, watch television, or even read. There are numerous toys that move and squeak that may also be interesting to your cat. Experiment and understand that what is exciting today may be boring tomorrow.

Rechecks and Weigh-Ins

After you and your veterinarian have put your cat on a weight loss program, it’s critical you determine if it’s working for your cat. Each cat is an individual and may require many changes in diet or routine before finding the ideal approach. In general, your cat should be weighed every month until the ideal weight is achieved. If there is no significant weight loss in one month, typically about one pound, then a new approach should be considered. Change daily calories, diet formulations, or physical activity routines. There is nothing more frustrating than persisting in a protocol that fails to achieve results, when a slight change could deliver significant improvements. Work closely with your veterinary healthcare team to reach your goals faster and more safely.

Reluctant Patients

What about the cat that wakes you at four in the morning to be fed or the cat that meows incessantly or head bumps you until you feed them? Our cats have often trained us well and know exactly which buttons to press when it comes to getting their way. Here are some tips for handling a pesky kitty:

·      Do not use a self-feeder. While this seems obvious, auto-feeders are nothing more than unlimited food dispensers. The same rule applies to community food bowls or food indiscriminate refilling. Careful portion control and caloric restriction is the most effective and safe method to help your cat reach a healthy weight.

·      Pet your cat or play with it when it begs for food. Many cats will be happy to substitute food for affection, so flip the equation and you may find that playtime displaces chowtime.

·      Feed small meals frequently – especially a last feeding for cats that wake you up in the wee hours asking for more food. Try dividing the total volume or calories into four to six smaller meals – whatever you do, don’t feed extra food simply because your cat asks you to!

·      When the bowl is empty and your cat is asking for more, add a few kibbles to the bowl. By a few, limit it to no more than five to ten tiny kibbles.

·      Offer fresh water instead of food. Many cats love fresh water so when they are eyeing an empty food bowl, trying filling up the water bowl instead.

Multi-Cat Households

What do you do if one cat is normal weight and the other is diagnosed with obesity? While there are countless creative solutions to this problem, here are a few we’ve found successful:

·      Feed each cat separately – this is the ideal solution for multi-cat households. Feed the cat diagnosed with obesity in one room while feeding the other cat elsewhere. After a prescribed time, generally 15 to 30 minutes, pick up any remaining food up (or the empty bowl) until the next feeding.

·      Feed the normal weight cat on an elevated surface where the cat with obesity can’t easily reach.

·      Do not leave food out while you’re away. 

Most cats will achieve their ideal weight within six to nine months. If the process is taking longer than this, some aspect of teh weight reduction program needs to be changed.

Typical minimum weight loss per month for a healthy adult act is about 0.5-lbs. Ideally, your cat will lose close to one pound per month. Some cats may need to lose weight slower while others may reach their weight loss goals more quickly.

If you're not seeing desired weight loss within 30 to 90 days, consider changing daily calories, pet food formulation, protein or fiber levels, or physical activity.

Be sure all potential underlying medical causes for obesity have been addressed before beginning any weight loss program. 

Always remember the reason for your efforts is to help your cat live a longer, healthier life. For most cats, the secret to weight loss is a dedicated, committed and concerned family member. It’s up to us as good stewards to protect them from harm and not inadvertently contribute to their premature death or development of debilitating diseases. Together – veterinary healthcare team, you and your cat – we can help your cat achieve its weight loss and health goals safely and successfully.