How To Get Your Cat To Lose Weight

The University of Illinois finds a diet that actually works!

By Justyne Yuen-Lee


Credit: Illumination / The Secret Life of Pets

A fat cat is kind of cute. They’re pudgy, adorable, and just beg to be cuddled! They are celebrated in the media – Garfield, Lucifer from Cinderella, and more recently Chloe from The Secret Life of Pets (pictured above). Indoor cats don’t usually go for walks, so miss out on that bit of exercise. In fact, they can generally be found lounging at home, moving only to the rattling of treats or dinner. With that kind of sedentary tendency, it’s not hard to believe that almost 60% of American house cats are obese or overweight (2016 survey by the Association for Pet Obesity Prevention). Chubby may be cute, but it’s not always healthy.


Excess weight can lead to health problems such as diabetes, skeletal stress, and reduced life expectancy. With weight loss, however, all of these problems are reversible.

Then again, how do you convince your cat to lose weight?


You can’t really convince them, per se, but you can feed them less.

The University of Illinois tested a new diet on 8 neutered chunky male kitties. The study involved gradually reducing their caloric intake over 8 weeks.


According to Kelly Swanson, one of the authors and a professor of animal and nutritional science, the intent was, “a healthy weight loss: getting rid of fat while maintaining lean mass. The risk with rapid weight loss, especially in a cat, is hepatic lipidosis. The body releases too much fat, and the liver gets bogged down… We targeted a 1.5 percent body weight loss per week, which falls in line with the range (0.5-2 percent per week) suggested by the American Animal Hospital Association.”


The Body Condition Score (BCS) is a 9-point scale used to measure a cat’s body weight.

A cat with a BCS score of 8 or 9 may look “like a little blimp.” An ideal BCS is 5. Each unit or point above this ideal 5 represents approximately 10 to 15% percent over ideal body weight. A cat that weights 20% over is considered overweight.


At the end of the study, all the cats showed a significant loss of weight with a median BCS score of 6. As a group, there was a 10% loss in body fat percentage, and an overall decrease in concentration of triglycerides (a type of fat the increases the risk of heart attacks and strokes). There was no significant change in their activity level, a reminder that cats will lounge at any weight no matter what.


Those this study proved that diets are a success, enforcing it at home is another story.

The Difficulties:

1. We’re not professionals


According to Swanson, “If you have a veterinarian do a BCS assessment of a pet and then have an owner do it, the owner will almost always underestimate the BCS.” Cat-lovers just think that their cats are just perfect the way they are and don’t have the medical knowledge to know that their cats are a little (or a lot) on the chubby side.

2. Diets are just as hard for cats as for people.


Bodies – both human and feline – need to adapt to new diets!

If you’ve ever tried to diet, after a few days (or even after the first), you might hit a road block. Same with cats – their meals had to continue to shrink after each week to compensate to how their bodies adapted to the lower calories. Essentially, their original diets had to be slashed by 20% to a maintenance diet to maintain a healthy weight.

3. We love our kitties too much.


The tiny healthy-sized portions may not seem to be enough for the people who love their cats. Some cat owners will reduce their cat’s meals to between 60 and 50 grams, but with a diet like this, their meals have to go to 45 to 40 grams to be successful. That’s a big difference and the little portions might make cat owners feel like they’re not providing as they should be.


But maybe with this study, cat owners will put their faith in science and see their chunky kitties reach an ideal weight! We might love their pudginess, but they’ll stay in our lives a lot longer if we trust the results of this study – 8 chunky cats became hunky cats!