Putting It into Action: Calorie Reduction Specifically for Companion Cats

In February, 2022, we provided a guideline on how to calculate your companion’s pet food for optimum weight loss. A few of our readers commented that the post and calculation seem skewed towards companion dogs. It is.  

That calculation – which is below – is good for cats that are considered inactive or prone to obesity. Some companion cats will more than likely shed a few pounds and ounces if they are being fed more than that calculation allows, but may not meet their target weight goal. So, a more exact calculation exists for companion cat weight loss because the life stage factor is less. 

In fact, you may feel wary about reducing your cat’s caloric intake using the exact calculation for cats, so you can ease into it by using the inactive or obese prone calculation. So, a gradual diet adjustment over a 4- to 7-day period may reduce the occurrence of negative gastrointestinal responses. 

No worries; we will show you how to do this and the steps you need to take. As well, we will apply the calculations to three different high moisture (wet) foods. Remember, at Hemopet, we prefer wet foods for cats.

How To…

#1. Veterinarian 

Before implementing any weight loss plan for your companion cat, you must consult your veterinarian. Your veterinarian can advise you based on your cat’s current health conditions, body condition score, and can give you a target weight goal for your cat based on food, treats and supplements. 

#2. Get to know the industry abbreviations

BW = Body Weight

RER = Resting Energy Requirement

MER = Maintenance Energy Requirement

LSF = Life Stage Factor 

kCal = Calories

#3. Need to Know Equations

The calculation for RER is RER = (BWkg^.75)x70. That’s body weight in kilograms to the power of 0.75, then multiplied by 70. 


MER will tell you how many calories your companion pet needs to consume per day based on their age.

Don’t worry; we will show you step-by-step how to accurately use these equations for your cat’s weight. 

#4. More on LSF 

LSF refers to how many calories per day a cat or dog needs based on its life stage. It is a number that is applied to different life stages such as gestation, lactation, kittens/puppies, age, neutered, and intact. In this instance, we want to shave weight. In most instances, we do want to shave weight as approximately 60% of cats are considered obese or overweight which can lead to several chronic health problems and unsightly veterinary bills! Anyway, the LSF for overweight or obese cats is 0.8.

#5. Calculation

Let’s say your cat should weigh 10 pounds. You need to feed your cat for that ideal weight. 

Companion Cat Optimal Weight Loss

Steps Calculations Unit Notes
Ideal Weight in Pounds 10 lbs.
Convert Weight to Kilograms 4.55 kg. Divide pounds by 2.2 for kilograms
RER = (BWkg^0.75) x 70 217.91 kcal/day Ideal for cats that are considered inactive or obese prone. The caret sign (^) is to the power of in Excel.
MER = RER * LSF 174.33 kcal/day Ideal calories per day for optimum weight loss in cats. LSF = 0.8

#6. Applying it to the food. 

First, we looked at a complete and balanced, grain-free turkey, dehydrated cat food. With this food, you add warm water, let it sit for a few minutes and serve it. (By the way, since it is in cups, you can apply this calculation to kibble as well.)

This food has 512 kCal/cup. 

Dehydrated Cat Food

Measurement Calories Multiply Calories in Cup by the Number Below
1 cup 512 1
3/4 cup 384 0.75
1/2 cup 256 0.5
1/3 cup 168.96 0.33
1/4 cup 128 0.25
1/8 cup 64 0.125
1 Tablespoon 32 0.0625
1/2 Tablespoon 16 0.03125
1 teaspoon 10.67 0.020833

Based on the dehydrated food, you could serve 1/3 cup plus a teaspoon. Many cat treats are 1-2 kCals, so you could make up the calories with those and skip the teaspoon. Remember: hitting the target of 174.3 calories per day will be difficult, so you want to aim around it. Maybe a little more one day, and a little less the next day.

Now, let’s apply this to wet (canned) cat food. The same companion pet food manufacturer also has a wet, minced, grain free turkey food. This has 5.5 ounces per net weight. So, you cannot rely on liquid measuring cups and will need to weigh each portion. 

The already wet cat food has 157 kCal/box.

Wet Cat Food

Measurement Calories
1 Box = 5.5 oz. 157
1 ounce 28.55
1/2 ounce 14.27


With this wet food, you can serve 1 box and ½ ounce per day. 

Now, let’s look at raw. Raw food is typically measured in net weight as well. One raw turkey recipe had 32 kCal/ounce. So, 32 x 5.5 ounces = 176 kCal for daily caloric intake. 

Bear in mind, if you rotate your companion pet’s foods – even staying with the same manufacturer – you will need to calculate the calories for each food. For instance, raw rabbit for cats was 36 kCal/ounce from the same manufacturer. Remember, 4 calories may not seem like a lot to you, but you weigh probably 12 times as much as your cat should. 

#7. Scheduled Feedings

We prefer scheduled feedings throughout the day. So, if your cat is not on a schedule, you may want to acclimate him to one before endeavoring weight loss. With scheduled feedings, you leave the food out for approximately 15-20 minutes and then refrigerate or toss out the uneaten portion.

#8. Extra Factors

Many cat companion parents have several cats. So, we can imagine that you are thinking, “I have one cat that needs to lose weight, but another that does not…what do I do?” The cliché “herding cats” exists for its appropriateness and is quite spot-on. 

Another factor is activity. Your question might be: What do I do if my indoor cat prefers to sunbathe on my bed instead of climbing on the expensive activity center I bought? 

We will address these issues in the next blog post and how to incorporate them for optimal cat weight loss. In this post, we simply wanted to give you the calculations for you to start thinking about safely taking the pounds off your cat.

Remember, talk to your veterinarian first before endeavoring on any weight loss plan for your companion pet!  


Cline, Martha G., et al. “2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats.” AAHA, American Animal Hospital Association, https://www.aaha.org/aaha-guidelines/2021-aaha-nutrition-and-weight-management-guidelines/home/

Weight Reduction in Cats. Association for Pet Obesity Prevention, https://petobesityprevention.org/weight-loss-cats

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