Is Your Cat Getting More and More Chubby?

This is Raja, our overweight cat!

Raja started out a reasonably svelte 12 lbs when we got her from a local shelter at age 7. Then, barely 2 years later, she was up to a hefty 15 lbs!

Diet cat foods were no help. Then, I happened to read a book: "Your Cat, Simple New Secrets To A Longer, Stronger Life" and it changed everything.

We invite you to follow our quest for a healthy weight-loss plan for this funny, personable and very talkative cat.

Hopefully, together we can help all our cats live healthier and thinner lives!

*Disclosure: I am compensated for sales from this site. Click for details.

2007-08-31

How to Read Cat Food Labels to Find Healthy Lo-Carb Cat Foods

Cat Food Guaranteed Analysis

At this point, we were more than ready to switch Raja, the fat cat, to low-carb canned cat food, but which ones? To help with label-reading, I found an easy to use formula that computes the carbohydrate content of wet (and dry) foods. It was in the book: Your Cat: Simple New Secrets to a Longer, Stronger Life by Elizabeth M. Hodgkins, D.V.M.

How to compare cat foods for their nutrient content and to determine the actual carbohydrates in each type of cat food:
Since no cat food lists the carbohydrate percent, you have to derive it from the "Guaranteed Analysis" percents that must appear on every can or bag of cat food. Ugh, math! Don't worry, it's not difficult.

Here's how to compute the actual carbohydrate percent in canned cat food:
The guaranteed analysis numbers on canned food typically look like this:
Protein 11%; Fat 2%; Fiber 1.5%; Moisture 78%; Ash 2.5%

There are other vitamins and compounds listed too, but they are in such small amounts that they can be ignored in this computation.

Notice there is no carbohydrate percent listed. This is typical. But here's a way to figure the carbohydrates from the guaranteed analysis: you simply add up all the guaranteed analysis percents for protein, fat, fiber, moisture and ash and subtract the total from 100%. That gives you the carbohydrate %.

For example, totaling the above percents for a can of cat food, you get 95.
Subtract that from 100 and you get: 100 - 95 = 5% carbohydrate (guaranteed analysis percent)

Wow! 5% carbs sounds really low... where can I buy that canned cat food? Not so fast. Unfortunately, what looks like a lo-carb cat food really isn't! The guaranteed analysis is a relative measurement, and takes into account the high moisture content of wet cat food.

To get an actual carbohydrate percentage, you have to see what the ingredient percents will be on a "dry matter" basis. That is, with the moisture removed from the equation. Then you can tell what your cat is really eating in a can of food, besides the water. After all, the moisture (water) content is typically 78% in canned cat food! (By the way, that moisture is a GOOD thing! It helps hydrate your kitty for healthy kidney function.)

Here's how to figure the actual nutrients, including carbs, in that same can of cat food:
  • Remember, the guaranteed analysis in our example was:
        Protein 11%
        Fat 2%
        Fiber 1.5%
        Moisture 78%
        Ash 2.5%
        Carbohydrate 5%
  • To remove the moisture from the equation, subtract the moisture percent, 78%, from 100% as follows: 100% - 78% = 22%
  • Then, divide each of the nutrients in the guaranteed analysis by the 22% you just computed:
    For example, if you divide the protein % by 22 you get: 11 / 22 = .5 which equals 50% dry matter protein (just move the decimal point 2 places to the right to get %.) By the way, that's a nice, high protein percent. Very good so far.
  • Now let's try to find the actual carbohydrate % in this can of cat food. Remember, it was a mere 5% in the guaranteed analysis, which sounds very low.

    But, if you divide 5 by 22 you get .227, which is a whopping 22.7% carbohydrates on a dry matter basis! Wow! Suddenly what we thought was a low-carb canned food is as high in carbs as some dry cat foods. Not good for our cat's diet at all!

I know it's a pain to have to figure all this out especially when you're in the store reading labels, but your cat will lose weight and be much healthier if you do.

To help with your label-reading, here's a shortcut that simplifies the math...


SHORTCUT: A simple rule of thumb for finding healthy and lo-carb canned cat food for your pet:

VERY IMPORTANT... This shortcut works ONLY for moisture between 75 - 80% guaranteed analysis and ONLY for canned cat food:
  1. First, add the Guaranteed Analysis percents for Protein + Fat + Fiber + Moisture + Ash
  2. If the total is 98% or higher, then actual carbohydrates will be 10% or less, which is what you are looking for.
Remember: The above shortcut only works for moisture content of 75 - 80% and ONLY for canned cat food.

If the moisture content is NOT in the range of 75% - 80%, then you must use the following 4-Step formula instead of the shortcut:


  1. Add Guaranteed Analysis Protein% + Fat% + Fiber% + Moisture% + Ash% = Total Guaranteed Analysis % (TGA%)
    (ex: Protein 11% + Fat 2% + Fiber 1.5% + Moisture 78% + Ash 2.5% = 95% (TGA%))
  2. Subtract: 100% - TGA% = Carbohydrate %
    (ex: 100% - 95% = 5%)
  3. Subtract: 100% - Moisture % = Dry Matter Divisor (DMD)
    (ex: 100% - 78% = 22 (DMD))
  4. Carbohydrate % divided by DMD = Actual (dry matter) carbs %
    (ex: 5 / 22 = .227 which is 22.7% actual dry matter carbs)

    The only foods we want are the ones where dry matter carbs are 10% or less.
This 4 step formula will work for all cat foods: dry, pouch or canned.

Here are some examples of how to compute carbohydrate % for canned and dry cat food:

Wet (canned) food example: Fancy Feast Cod, Sole & Shrimp

Guaranteed Analysis:
Protein: 13%
Fat: 2%
Fiber: 1.5%
Moisture: 78%
Ash: 3.5%

Total: 98%
To calculate the Carbohydrate amount on a dry matter basis:
Subtract Total Guaranteed Analysis % from 100%
100% - 98% = 2% carbohydrate
Wait, that's NOT the actual carbs! To compute the actual dry matter carbohydrate percent, subtract the moisture % from 100%
(100% - moisture %) = 100% - 78% = 22%
Then, take 2% (percent of carbs computed) divided by 22% = .09 = 9% carbohydrate.
So on a dry matter basis the amount of carbohydrate in this canned food is 9 percent. Good for your cat!

Dry food example: Science Diet Indoor Cat Mature Adult

Guaranteed Analysis:
Protein: 29%
Fat: 17.5%
Fiber: 10%
Moisture: 11%
Ash: 2.5%

Total: 70%
To calculate the Carbohydrate amount on a dry matter basis:
Subtract Total Guaranteed Analysis % from 100%
100% - 70% = 30% carbohydrate
Wait, that's NOT the actual carbs! To compute the actual dry matter carbohydrate percent, subtract the moisture % from 100%
(100% - moisture %) = 100% - 11% = 89%
Then, take 30% (percent of carbs computed) divided by 89% = .337 = 33.7% carbohydrate.
So on a dry matter basis the amount of carbohydrate in this dry food is about 34% percent. Not good for your cat!

NOTE: You don't have to go through all the above calculations when you're shopping for canned cat food. If the Guaranteed Analysis moisture % is 75-80%, then simply use the SHORTCUT above to find low-carb food.


So, armed with the shortcut and the 4 step formula, I'm heading out to find some decent canned foods for Raja.

Coming up... the results of my hours of research at pet food stores.

1 comment:

  1. I've researched wet cat food and you're right to look for high protein, low carb recipes. One of my cats died of cancer. That's when I learned that carbs can really contribute to DNA damage and abnormal cell growth, ie, cancer. Kitties don't deserve that!

    ReplyDelete

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