I did a few calculations for your cat to provide an estimate of his daily caloric needs and the amount to feed him to attain a gradual weight loss. Your veterinarian probably informed you that it is very important to avoid rapid weight loss in overweight cats because rapid weight loss can predispose overweight cats to a serious disorder called feline hepatic lipidosis (accumulation of fat in the liver).
Okay, here are some guidelines for your guy:
Current Weight is 21 lbs. Using an equation for overweight cats, his energy needs are approximately 320 kcal per day. We typically start with a calorie deficit for cats (when we use this formula for energy needs) of about 60 %. So this gives you about 192 kcal per day for your cat. However, it is not unusual at all to need to go to 50 % reduction in cats, which would be 180 kcal per day. (We generally do not advise going below 50 percent of needs without being under the direct supervision of your veterinarian, again because of health risks for cats).
Iams weight control (the over-the-counter food) has a caloric density of 349 kcal/cup. So, your boy should get between 0.51 and 0.55 cups per day (~ 1/2 cup of food, total, per day). So, by giving him 2/3 of a cup per day, you are still feeding him a bit more than he needs for weight loss.
If you feel that feeding 1/2 cup total a day will leave him feeling very hungry and uncomfortable, I would suggest switching him to a veterinary prescribed therapeutic diet for weight loss. These are all lower in calories than the OTC products and so you would feed a larger volume to get the same caloric intake (and weight loss). Using the Iams veterinary product as an example: Their dry product contains 268 kcal per cup, so in you could feed about 0.7 cups per day, about what you are feeding now, in volume. The other benefit is that almost all of the weight loss products that are sold as veterinary diets also have a canned version (the OTC products often do not).
So, bottom line is that my recommendation is to either reduce the amount of the OTC product that you are feeding a bit more, or a better option, switch your guy to a veterinary therapeutic food for weight reduction so that you can feed a bit more volume of the dry product and/or add a bit of canned weight control food to his diet, since he enjoys wet food. Last, you should avoid feeding less of a normal maintenance food, or going too low in volume with the OTC food you are currently feeding, to avoid nutrient deficiencies. Weight loss foods are specifically formulated to still provide all of your cat' essential nutrients while still providing less calories and so are best for weight loss programs.
Finally, you asked about brands. There is still a lot of controversy in the pet nutrition world regarding the best approach to weight loss foods. The product that you are feeding has reduced fat and relatively increased digestible carbohydrate, and normal fiber. This provides moderately reduced calories in the food and does not impact GI function to a great degree. Another approach is to dilute a food's calories with non-fermentable fibers. When this approach is used, you will see increased defecation and increased stools, which is undesirable to some owners. However, the philosophy of that approach is that the animal will feel more sated (full) and more satisfied on the bulkier diet. Both approaches can work, and each has advantages and disadvantages. If your guy likes the food you are feeding and accepts it, I would suggest staying with that product for now and see if you can get weight loss with the suggestions above, or with switching him to the veterinary version of the same food, since switching brands may cause some changes in his GI health and he may not accept the new food.
Sorry for the length of this! I hope this is helpful to you and best of luck with your boy and his weight loss!
Owner, AutumnGold Consulting
Linda gave you some great information about the prescription diet foods and controlling the calorie count. Like she said, it is very important to try to increase his activity as well. It is great that you are taking responsibility for reducing your cat's weight.
I seem to have the best results in my patients using a canned diet. They seem to lose the weight better than those cats that won't eat canned food and are fed only dry. The canned food will have more protein and lower carbs which will help promote fat loss and not muscle loss. The cats seem to be more satisfied with the amount of food as well. There is water in them which helps fill the stomach and the higher protein helps to promote satiety. The prescription diet canned foods seem to get the best outcome.
I hope this helps.
Judy Karnia, DVM
Scottsdale Cat Clinic
It is probable that the brand of weight loss food that you tried from your veterinarian did have increased fiber. Some cats and dogs tolerate these well, while others do not. There are veterinary prescription foods for weight loss that do not have drammatically increased fiber levels, but not all veterinary clinics carry these, so you may need to ask around a bit.
Also, I should have mentioned this earlier (but my post was already long enough). You did not mention if you have tried to increase your cat's daily activities at all. This is an important component of any weight loss program because it not only increases calories expended, but also helps to prevent loss of lean body tissue during weight loss programs. If you are not already doing so, walking cats outdoors on a harness is enjoyable to many cats, and purchasing a variety of interactive cat toys to engage your cat and increase his activity is also helpful. Cats love novelty in toys, so we usually suggest buying several types and rotating them every few days to help to maintain your cat's interest.
Best wishes - and good luck with your cat's weight loss program -
We tryed him on a prescription dry food that we got from the vet but I think it had to much fiber because it caused him to have problems with his bowels. His bowel movement would be very hard and he would occasionally have trouble getting it out (run through the house with it hanging out). His vet did say to give him 1/4 cup twice a day but he acted starved!!! I will go back to the vet and ask if there is something with less fiber that we could give him.
Thank you for your advice!
I agree with Dr. Karnia's comments regarding a canned prescription weight reduction food for your fellow, especially since you indicate that he prefers canned food. In addition to helping to preserve muscle tissue, there is very good evidence that the high protein, reduced carbohydrate foods are beneficial for cats who are diabetic or at risk for diabetes (glucose intolerant). You do not mention if your cat was hyperglycemic, but I imagine that your veterinarian did tell you that being overweight is an important risk factor for feline diabetes. So, all things considered, and given Dr. Karnia's experiences with her client's cats, I agree that finding a canned, prescription weight loss food for your boy is a very good approach for his weight loss program.
Best of luck with his weight loss - he is lucky to have a caretaker who is so committed to his health and care!
Thank you for all your advice. My Vet does not carry canned prescription weight loss so I will check out other vet's to see what I can find. I'm sure my cat will be thrilled to have the moist.
One more question: Does changing from dry to moist require a gradual change? Should I start by mixing a little of the moist into his dry?
If your cat is used to all dry then it is best to gradually switch to the canned. You can mix it in or give it to him in a separate bowl. If he doesn't eat all the dry at once, it is better to offer the canned separate so you are not leaving it out for long periods.
Start with just a teaspoon of the canned twice daily and work it up gradually over the course of 2-3 weeks. It will be less likely to upset his stomach and intestines that way.
Make sure you stick to the calorie count with the canned also. Your veterinarian can provide the calorie count for the diet you select. Can your veterinarian special order the food for you?