If your cat consumes more calories than she burns, she will gain weight. So, how many calories should your cat eat in day to maintain a healthy body weight?

Like people, cats are individuals; some have higher metabolisms than others. Things that affect how heavy or thin a cat is include (Reference 1):

  • Genetics
  • Sex
  • Spayed? neutered?
  • Hormonal changes eg. hyperthyroidism, diabetes

The feeding guidelines on cat food cans or packages are a start but they can be misleading. Many of these guidelines are based on feeding intact cats and often recommend 25-35% more food than most housecats (spayed or neutered) need to eat. Immediately after spaying or neutering, the cat undergoes hormonal changes (changes in estrogen, progestin, insulin-like growth factor) that affect metabolism. The results are an increased appetite, decreased energy requirements, changes in glucose tolerance and fat metabolism. (Reference 1)

How Many Calories Should Your Cat Eat in a day?

A Rule of Thumb

  • Most average-sized (9 to 11 pounds) spayed and neutered cats need to eat about 200 kcal daily to maintain lean body condition.
  • Neutered males may need to eat less, about 180 kcal/day. (Reference 1)

Monitor your cat’s body condition

  • Be attuned to factors that can lead to weight gain or loss, such as disease (hyperthyroidism), feeding behavior (a cat eats another cat’s food) or lifestyle change (access to a catio).
  • Monitor your cat’s body weight, his body condition score and his muscle condition score regularly.

How Many Calories Should Your Cat Eat?

Weigh Your Cat

You can weigh your cat at the veterinary clinic but, even better, purchase a baby scale to weigh your cat at home. This is more convenient, especially if your cat is on a weight-loss program and needs to be weighed frequently. You can make this fun by training your cat to get on the scale for a yummy reward (something low calorie, of course!)

“How Do I Look” – the Body Condition Score (BCS)

Look at your cat’s profile from above and from the side. Ideal body condition is defined as a visible waist (when viewed from above) and tummy tuck (side profile). You should be able to easily feel his ribs under his skin and fur. Compare what you see with the pictures on the Body Condition Chart.  Give your cat a score.

Once you know your cat’s weight and Body Condition Score, you can get a calorie estimate from a convenient calculator at https://petnutritionalliance.org/resources/calorie-calculator?type=cats

How Many Calories Should Your Cat Eat?

Here are some photos of Gus, who currently weighs 12.50 pounds. You can feel his ribs but there is some fat over them. His waist and shoulders are distinguishable but he does not have much of an abdominal tuck.  We will give him a BCS of 6. The Pet Nutrition Alliance site recommends an ideal weight of 11.4 lbs and 216 kcal daily for weight loss.




Lean Body Mass and Healthy Weight

In a previous post, we talked about Lean Body Mass (LBM) and the benefits of a higher LBM for cats:

  • A higher percent of muscle will boost your cat’s metabolism
  • Make it easier for her to maintain a health body weight
  • Can help your cat live longer.

Choosing a diet to promote LBM – A Math Problem

Studies indicate that to maintain LBM, a cat should consume around 5.2 g protein per kg or 2.3 g protein per pound. (Reference 2). Using your cat’s weight, you can multiply by 2.3 (weight in pounds) or 5.2 (weight in kg) to estimate the protein he or she needs. Gus weighs 12.5 lbs and needs 28.8 grams of protein daily.

Here are two canned foods and two dry foods, with guaranteed analysis and protein content. As you can see in the chart, there is only one food (wet) out of the 4 foods that will provide Gus with the protein he needs while he loses weight eating 216 kcal daily.  Food 2 can give him the 28.8 g protein in 183 kcal. (See “How Much Protein Should You Feed Your Cat?” for estimating the amount of protein in a food.)



Food 1 (wet)

Food 2 (wet)

Food 3 (dry)

Food 4 (dry)

Crude Protein (%)





Crude Fat (%)





Crude Fiber (%)





Moisture (%)





Ash (%)





Carbohydrate (%)





MER (kcal/kg)





Protein (g/ 100 kcal)





Cat’s weight (lbs)





Protein for LBM





Calories of Food Needed (kcal)





The muscle condition score

There is one more thing we need to monitor – the cat’s Muscle Condition Score (MCS).  Loss of muscle  over the spine, shoulder blades, skull, and hips (that “bony” feeling) is an indicator of LBM loss.  Although you cannot prevent loss of muscle due to aging,  you may be able to slow it down by feeding a higher protein diet.  Here is a chart to help score the muscle condition.  Gus, at age 7, still has normal muscle mass, which we will try to maintain by ensuring he gets enough protein in his diet.

Feeding your cat is more than just how many calories should your cat eat.  We must balance calories and nutrients and monitor weight, BCS and MCS regularly to make sure the feeding plan is working.  AAFCO labeled foods ensure that your cat receives the basic nutritional requirements.  Optimal nutrition for the individual cat, especially one with medical conditions, may require a more detailed plan and possibly the services of a board-certified veterinary nutritionist.


  1.  Zoran, Debra. “Feline Obesity: Clinical Recognition and Management” Compendium, June 2009 (Vol 31, No 6).
  2. Laflamme DP, Hannah SS. Discrepancy between use of lean body mass or nitrogen balance to determine protein requirements for adult cats. Journal of Feline Medicine and Surgery. 2013;15(8):691-697. doi:10.1177/1098612X12474448

Want to keep up with the world of cats? Subscribe to The Feline Purrspective?


Your cat evolved to eat a diet high in protein.  How much protein should you feed your cat? Research suggests feeding enough protein to maintain Lean Body Mass.

Measuring Protein in Food

Nitrogen Balance

The protein content of a food is determined by measuring the nitrogen in it. The difference between the nitrogen we that take in (by eating food) and the nitrogen we put out (in urine) reflects the gain or loss of total body protein and is called the nitrogen balance. Traditionally, the amount of protein that maintains a zero nitrogen balance was considered the minimum protein required to be healthy. [Reference 1]

Nitrogen is one of the most common chemical elements in the universe. The atmosphere surrounding the Earth is about 78% nitrogen. Proteins, those molecules in our bodies that are used to build and repair tissues and act as hormones or enzymes, contain nitrogen. 


Lean Body Mass

Recent research in both human and animal nutrition suggests that it is not enough just to maintain a zero nitrogen balance – animals and humans should consume enough protein to maintain their Lean Body Mass (LBM). Lean body mass is the difference between total body weight and the weight of body fat. LBM is made up of the muscle and internal organs.

Muscle and internal organs have a higher metabolic rate than fat. So, a higher percentage of muscle will boost your metabolism, help you maintain a healthy weight, and may help you to live longer. [Reference 2]

How much protein should you feed your cat?

A study followed 24 adult neutered male cats over several months to compare the amount of protein necessary to achieve nitrogen balance with the protein required to maintain LBM (measured by dual energy x-ray absorptiometry or DEXA).

The cats were divided into 3 groups and fed diets with different amounts of protein: one group received a “low” protein diet, the second a “moderate” protein diet and the third group was given a “high” protein diet. [Reference 1]

Results: more dietary protein was required to maintain LBM than to satisfy the nitrogen balance.

  • Nitrogen balance was maintained with 1.5 g protein/kg (0.7 g/pound) of body weight.
  • LBM was maintained with 5.2 g protein/kg  (2.3 g/pound) of body weight .

how much food will give your cat enough protein?

There is no easy answer to this. Not only are there differences in the metabolisms of individual cats and different food formulations, not all the energy in that can or bag of cat food can be metabolized.

To measure how much metabolizable energy (ME) a particular cat food provides your cat, you would need to do a “feeding study”.  Such a study measures what goes into the cat and what comes out. The difference is what is metabolized.

Feeding studies are expensive so the pet food industry has devised formulas to estimate the amount of metabolizable energy (ME) in a food using the guaranteed analysis on the pet food label. (The percentage of carbohydrates can be calculated by adding up the protein, fat, crude fiber, moisture and ash listed in the guaranteed analysis and subtracting this total from 100%.)

One of the simpler formulas used is the Atwater equation shown below.   [Reference 3]

ME (kcal/kg) = [4x Crude Protein(%) + 4 x Carbohydrate (%) + 9 x Crude Fat (%)] x 10

Nutrients for feeding guidelines are reported per 100 kcal of ME. To find out how much protein your cat food provides per 100 kcal of metabolizable food, we return to the crude protein estimate and reference it to the ME.

Grams protein/ 100 kcal ME = [Crude Protein(%) x 1000] / ME (kcal/kg)

How much protein should you feed your cat?  Let’s look at some protein estimates using values from a few typical food labels. These calculations are done on an “as fed” basis.

  Crude Protein (%)



Crude Fat (%) ME (kcal/kg) Protein

(grams/100 kcal)

Canned A 12 2.1 2.2 762 15.7
Canned B 10 3.8 5 942 10.6
Dry A 43 24.5 19 4410 9.8
Dry B 33.5 30.6 21.1 4463 7.5


Let’s take the example of a 10 lb or 4.5 kg cat in average condition – not fat, not thin. Per the research referenced above, this cat would need about 23 grams of protein daily.

The average 10 lb cat burns about 200 kcal daily. Looking at the foods above, 200 kcal of Canned A would give our 10 lb cat more than 23 g protein; Canned B gives him 22 g, a little short of the daily goal. Neither of the dry foods provide enough protein in 200 kcal to meet the lean body mass requirement: Dry A provides 19.6 g per 200 kcal and Dry B, 15 g per 200 kcal.

How much protein should you feed your cat?

    • The 5.2 g protein/kg body weight is the result of two studies – more work is needed to establish accurate protein requirements.
    • Protein requirements may vary with age, gender, and breed.
    • Medical conditions such as chronic kidney disease can also affect your cat’s protein requirements.

Your veterinarian is a good resource for helping you figure out how much protein to feed your cat. He or she can assess your cat’s body and muscle condition and health to determine if your cat is receiving enough protein and calories.

In our next post, we will consider how many calories your cat should eat every day and how Body Condition Score and Muscle Condition Score can give you an idea of your cat’s body composition, muscle-to-fat ratio and nutritional status.



  1. Laflamme DP, Hannah SS. Discrepancy between use of lean body mass or nitrogen balance to determine protein requirements for adult cats. Journal of Feline Medicine and Surgery. 2013;15(8):691-697. doi:10.1177/1098612X12474448
  2. Zhang X, Wang C, Dou Q, Zhang W, Yang Y, Xie X. Sarcopenia as a predictor of all-cause mortality among older nursing home residents: a systematic review and meta-analysis. BMJ Open. 2018 Nov 12;8(11):e021252. doi: 10.1136/bmjopen-2017-021252.
  3. Asaro NJ, Guevara MA, Berendt K, Zijlstra R, Shoveller AK. Digestibility Is Similar between Commercial Diets That Provide Ingredients with Different Perceived Glycemic Responses and the Inaccuracy of Using the Modified Atwater Calculation to Calculate Metabolizable Energy. Vet Sci. 2017 Nov 8;4(4):54. doi: 10.3390/vetsci4040054.

Want to keep up with the world of cats?  Subscribe to The Feline Purrspective!



What goes into Gus’s food dish?

In the last post, we spoke about your cat and some of her unique nutritional needs. She is an obligate carnivore, designed to eat small animals but she does have some flexibility and can use carbohydrates for energy. Lean times are hard for cats and their livers are slow to process stored fat. Unlike other mammals, her body does not synthesize the amino acids, taurine and arginine, and these must be provided in her diet.

Cats dine on small rodents, rabbits, birds, reptiles and insects. They will consume the entire animal, fur, tendons, blood, gut contents…  Even if your cat is an active outdoor hunter, you are going to offer her some food and will probably turn to some of the many commercial cat foods available.

feeding your cat A complete and balanced diet

A feral cat gets about 52% of his energy from protein and 46% from the fat of the prey he eats.  Your cat will need a diet with protein and fat.  Like other animals, the cells in his body require glucose (a carbohydrate) to function. Cats typically use proteins for energy and produce glucose via gluconeogenesis, regardless of fasting or starvation. But cats are flexible and if they consume a minimum amount of protein, they can use dietary carbohydrate as a source of glucose, and spare the proteins for other tasks, such as building and repairing tissues and acting as hormones (reference 3). When feeding your cat, you will want to offer him some fat and carbohydrates, in addition to protein.

How much fat? carbohydrates? protein?

Like people, cats are individuals and their dietary intake varies. Most of the time, we feed our cats and note if they gain or lose weight, and adjust their intake accordingly. 

What is a complete and balanced diet for a cat? A complete and balanced diet will provide the cat all the nutrition she needs, including essential amino acids, protein, fat and minerals. Most pet foods on the market will have a label stating that the food is formulated according to the guidelines established by the American Association of Feed Control Officials (AAFCO) or in Europe, the European Pet Food Industry Federation (FEDIAF).  We look briefly at the AAFCO guidelines.


The original guidelines were formulated in 1990 and have been revised several times; the latest iteration was in 2007-2008. The guidelines establish nutrient concentrations for ingredients typically sourced for pet food.  Nutrients include protein, fat, essential amino acids, vitamins and minerals.

AAFCO profiles guarantee that the product contains the minimum (or maximum) concentrations for the nutrients in the profile.   For example, protein in excess of the minimum concentration is acceptable whereas a maximum concentration for Vitamin D avoids concerns with toxicity. There are two profiles for cats: one for “growth and reproduction” and a second for “adult maintenance”.  The chart below shows the recommendations for fat and protein in cat foods. (Reference 1)

AAFCO Nutrient Profile Protein Fat
Growth & Reproduction 30% 9%
Adult Maintenance 26% 9%

The Cat Food Label:

The label that goes on a can or bag of cat food has eight items.  We will focus on item 4: the Guaranteed Analysis. This is a list of the percentage of each of the nutrients in the food. The minimum percent of crude protein and crude fat, and the maximum percent of crude fiber and moisture must be included. (See Feeding Your Cat: Choosing a Food for more about AAFCO labels).


There is not an established requirement for fat. The minimum concentration of 9% in the AAFCO guidelines is based on recognition of the role that fat plays in the diet: a source of essential fatty acids, a carrier of fat-soluble vitamins, enhances palatability, and supplies adequate calories. (Reference 1)

Fats are used for energy (providing 9 kcals/g) and if there is more fat than the cat needs in his diet, he will store it – like those “chonky” cats on the internet. Fats also increases the palatability of the diet and may encourage over-eating.  There are low-calorie diets containing less than 9% fat that have an AAFCO label.


Carbohydrates are not listed in the guaranteed analysis. An estimated percentage of carbohydrates can be calculated by adding up the protein, fat, crude fiber, moisture and ash listed in the guaranteed analysis and subtracting this total from 100%. (Reference 2).

In the wild, cats eat a diet that is primarily protein and fat. This leads many folks to think that cats do not need or use carbohydrates. But like other animals, their cells require glucose to function.  They can either get this by breaking down protein or from dietary carbohydrate.

Carbohydrates are necessary in the processing of commercial cat food, particularly kibble. Most commercial dry foods contain 33-45% as carbohydrates (dry matter)(Reference 4); canned foods tend to have less than 10%.

Some carbohydrates in the cat’s diet will not present a problem providing he gets enough protein. Too much carbohydrate (even highly digestible carbohydrates) can cause diarrhea, flatulence and bloating (Reference 3).  Feeding your cat too much carbohydrate can also “dilute” the protein in the food – the cat may reach satiety before getting his necessary protein. Diets greater than 60% dry matter risk nutrient unbalance.  Even smaller amounts (50% dry matter) can be a problem – for example, kittens need a lot of protein and too many carbohydrates will reduce the protein available to them. (Reference 4)

And Now for Protein…

Your cat is an obligate carnivore and protein is an essential part of a cat’s complete and balanced diet.  Cats have distinct dietary requirements for protein and these will be the subject of the next post in “Feeding Your Cat”.


  1. AAFCO Methods for Substantiating Nutritional Adequacy of Dog and Cat Foods. https://www.aafco.org/
  2. Heinz, C. “Carb Confusion: Part 2. Measuring and Comparing Carbohydrates in Pet Foods” (9/27/21) https://vetnutrition.tufts.edu/2021/09/carb-confusion-part-2-measuring-carbs/.
  3. Verbrugghe A, Hesta M. Cats and Carbohydrates: The Carnivore Fantasy? Vet Sci. 2017 Nov 15;4(4):55. doi: 10.3390/vetsci4040055. PMID: 29140289; PMCID: PMC5753635.
  4. Kirk, Claudia. “Feline Nutrition: What Is Excess Carbohydrate?”. Purina Companion Animal Nutrition Summit: Tackling Myths About Pet Nutrition, Atlanta, GA March 21-23, 2013.

Want to keep up with the world of cats?  Subscribe to The Feline Purrspective!