In North America, obesity is the most common preventable disease in cats and is one of the most common overall. Almost 60% of domestic cats are overweight.

What is obesity?

Obesity is an accumulation of excess body fat.

Extra body fat causes extra body weight, so we can measure weight to determine whether a cat is overweight or obese. This is easier than measuring body fat.

Using body weight as a guide, cats are considered overweight when they weigh 10-20% above their ideal body weight. Cats are considered obese when they weigh more than 20% above their ideal body weight.

What are the risks posed by obesity?

Obesity shortens a cat’s life and makes them more likely to develop diseases. Even being moderately overweight reduces a cat’s life expectancy. A 2.8-fold increase in mortality has been shown in obese cats (8-12 years old) compared to lean cats.

A large, lifetime study of Labrador retrievers found that a moderately overweight group of dogs lived nearly two years less than their leaner counterparts. This is a sobering statistic, as it was always accepted that heavy dogs lived a shorter time than lean dogs, but only by about 6-12 months. It is reasonable to expect we would see similar results in a study performed on overweight cats.

"Scientific evidence now reveals that fat tissue is biologically active. It secretes inflammatory hormones and creates oxidative stress on the body’s tissues, both of which contribute to many diseases and decrease quality of life."

Previously, fat was considered a relatively inactive tissue, simply storing excess energy calories and adding to body mass. Scientific evidence now reveals that fat tissue is biologically active. It secretes inflammatory hormones and creates oxidative stress on the body’s tissues, which contributes to many diseases and decreases quality of life. Treating obesity as a chronic, low-level inflammatory condition is the new approach.

Obese cats develop an increased risk of the following problems:

• Cancer
• Diabetes mellitus
• Heart disease and hypertension
• Osteoarthritis and faster degeneration of affected joints
• Urinary bladder stones
• Anesthetic complications

Obese cats who stop eating are at significant risk of developing a potentially life-threatening liver condition called hepatic lipidosis. Other potential complications of obesity in cats include skin and coat problems and difficulty fighting infectious diseases.

How can I tell if my cat is obese?

The first step in dealing with an overweight or obese cat is to recognize and acknowledge that there is a problem. Unfortunately, we are inundated with images in the media of overweight cats, making it challenging to understand what healthy looks like. Your veterinarian and veterinary health care team can assist with an assessment.

You can assess your cat's body condition at home by checking how much fat they have covering their ribs and comparing that to the feel of your hand. Start by feeling the dog’s ribs just behind their front legs.

• If the ribs feel like the back of your hand, your cathas an excellent body condition.
• If the ribs feel like your knuckles, or stick out like knuckles, your dog is too thin.
• If the ribs feel like the palm of your hand, your dog is overweight.

This “hand test” is also a good measure of weight loss progress between formal weigh-ins.

"Your veterinary health care team will provide an estimated ideal body weight to use as a target."

Your veterinary health care team will provide an estimated ideal body weight to use as a target. Still, it is important that they also do regular body condition assessments to ensure your cat is moving toward having a normal body weight and body condition. Most veterinary practices use a body condition scoring system on a scale of either 1-5 (3 being ideal normal) or 1-9 (5 being ideal).

How do I adjust my cat’s meals to help him lose weight?

Once you have identified that your cat is overweight or obese, it is essential to adjust feedings for weight loss using an appropriate nutritional product, portion, and meal frequency. Veterinary-formulated diets help with healthy and safe weight reduction in cats, such as Hills® Prescription Diet Metabolic, Royal Canin® Satiety Support Weight Management, and Purina Overweight Management®. It is not appropriate to simply reduce the volume of their current food: this will cause malnourishment over time.

"It is not appropriate to simply reduce the volume of their current food: this will cause malnourishment over time."

Feeding a special diet with a lower overall calorie density and an appropriate nutrient balance is essential. Your veterinarian can recommend and provide the best diet for your cat.

Once the new food has been selected and the new portions are determined, it is critical that you are consistent with feeding – portions and meal frequency – and resist the temptation to provide extra snacks. Ask your veterinarian how to include treats in your cat’s diet plan.

Monthly weigh-ins are a critical component of successful feline weight loss and keep everyone accountable. It is important to verify weight loss, to ensure that weight loss is neither too rapid nor too slow, and to determine when your cat has achieved a healthy body condition.

For more tips on reducing your cat’s weight, see the handouts “Creating a Weight Reduction Plan for Cats” and "Exercising Your Cat for Weight Loss".

What happens when we reach our weight-loss goal?

Once ideal body weight and condition have been achieved, it is important to maintain your cat’s weight. It is important to gradually increase the amount you feed your cat while she maintains this healthy weight until she can safely transition to a maintenance diet (think of it as a "reverse diet" to help her metabolism adapt to a "normal" amount of food). 

This process can take two to three months but is the best way to prevent a weight-gain rebound. Some cats, especially those who exhibit begging behaviors and are less active, may benefit from remaining on the weight-loss diet with slightly higher meal portions for maintenance. Your veterinary team can guide you through this process.

"The benefits of normalizing body weight and condition make the effort well worth it."

Portion control is critical at this stage to prevent regaining weight. After so much hard work, a relapse into obesity would be unfortunate. Yo-yo weight loss and gain are no healthier for cats than for humans. The benefits of normalizing body weight and condition make the effort well worth it.