Helping Fat Cats Lose Weight

Updated: May 05, 2015
Published: October 19, 2012
Share this:

Fat cats have been in the news recently. First, there was the sad story of Meow, a 39 pound cat from New Mexico that died of lung failure before a weight loss program could save his life. Next came Skinny, a 41 pounder that is up for adoption in Texas.

All the media attention is good if it can help people understand that fat cats are not healthy cats. What we really need, however, are proven solutions to the problem of feline obesity.

A recent article published in the Journal of Feline Medicine and Surgery touches upon just this subject. It is entitled "From problem to success: feline weight loss programs that work." The researchers make the following points:

Obesity is the most common unhealthy nutritional condition that is recognized in cats. Documented associated health risks include diabetes mellitus, lameness, non-allergic skin disease, feline lower urinary tract disease and idiopathic hepatic lipidosis.

It has been reported in some developed countries that as much as 40-50% of the feline population may be overweight or obese, with middle-aged cats, male cats, mixed-breed cats and neutered cats being at greatest risk.

Simply recommending a diet designed for weight loss fails, in most cases, to result in successful weight loss in the obese or overweight cat. A more in-depth approach that centers on communication and commitment, alongside a program of feeding a predetermined amount of a specific diet plus exercise and enrichment of the cat's life, offers a chance for a healthy result.

I approach feline weight loss in the following manner, which matches up well with the dietary recommendations made in the aforementioned paper.

  • Weigh the cat and convert pounds (lbs) into kilograms (kg) if necessary by dividing by 2.2
  • Calculate the cat’s resting energy requirement (RER) using the following formula: 70 x [(weight in kg)] 0.75
  • Multiply the resulting number by 0.8 to determine the number of kilocalories that the cat should eat to lose weight
  • Find the caloric density of the food that I think will work best for the patient in question, and then divide the number of kcal the cat needs by the kcal/can (yes, canned food is generally better for weight loss than is dry). This gives us the amount of food we’ll offer to the cat at the beginning of the weight loss program

Here’s what the calculations look like for a typical 18 pound cat.

18 lbs / 2.2 = 8.2 kg

70 x 8.2 0.75 = 338 kcal/day

0.8 x 338 = 270 kcal/day

270 kcal/day / 156 kcal/can = 1.73 cans per day (to be practical, 1¾ cans per day)

I aim for the weight loss program to be complete in 6 months (longer if the cat is morbidly obese). So, I’ll subtract her ideal weight from her current weight and divide that by 6 to determine roughly how much she should be losing each month. This allows us to adjust her caloric intake accordingly at our monthly weigh-ins.

Most importantly, that 1¾ cans per day from our example is ALL the cat is allowed to eat. I recommend that in the morning, owners put the cat’s total daily ration in a Tupperware container and all meals and snacks can only be taken from there throughout the day.

It sounds (and is) tough, but if we can prevent more cases like Meow’s, it’s well worth the extra diligence.

Dr. Jennifer Coates


From Problem to Success: Feline weight loss programs that work. Kathryn Michel and Margie Scherk. Journal of Feline Medicine and Surgery, May 2012; vol. 14, 5: pp. 327-336.

Image: kuban_girl / via Shutterstock