Cat Obesity Guide: How to Assess Your Cat's Body Condition

Why Weight Matters

At the clinic where I work, many of the cats with liver disease or diabetes were once very overweight. One of the vets once told me, quite earnestly: “Don’t let your own cats get too fat.”

Weight can be managed, though. The first step is figuring out where your cat actually stands.

Body Condition Score (BCS): More Important Than the Number on the Scale

Many people only look at the weight on the scale, but that’s not accurate enough. A 5 kg Maine Coon might be underweight, while a 5 kg mixed breed could already be overweight.

Vets use a Body Condition Score (BCS) to judge how lean or heavy a cat is. The 9-point scale is the one most clinics use, and it’s the one in the World Small Animal Veterinary Association (WSAVA) guidelines.

How to Assess

Evaluating BCS requires both looking and feeling, checking three areas:

1. Ribs

• Gently run your palms over your cat’s ribs, no pressure needed
• Ideal: You can easily feel the ribs, but can’t see obvious rib outlines
• Overweight: You need to press firmly to feel ribs, or can’t feel them at all

2. Waist

• View your cat from directly above
• Ideal: There’s a visible waist curve behind the ribs (like the top of an hourglass)
• Overweight: No visible waist; body appears oval or rectangular

3. Abdomen

• View from the side
• Ideal: The belly line tucks up slightly from chest to rear
• Overweight: Belly sags, or runs parallel to the ground

BCS Reference Chart

For pictures, see the WSAVA Body Condition Score chart (PDF).

The goal is BCS 5. At 6, start paying attention. At 7 or above, talk to your vet.

Muscle Matters Too

Body condition score only evaluates fat, not muscle. Some cats can be both “overweight” and “muscle-wasted,” looking round overall while the spine and shoulder blades become prominent.

This is particularly common in cats over 10 years old. If your cat’s back feels noticeably bonier, have your vet take a look, even if the weight hasn’t changed.

Why Cats Gain Weight Easily

Metabolic Changes After Neutering

Neutering lowers a cat’s calorie needs by roughly 20-25% while often increasing appetite. Keep feeding the same amount and the weight will likely creep up.

After neutering, ask your vet to recalculate your cat’s portions. To work out daily calories from body weight yourself and turn them into grams of food, see the cat feeding guide.

Free-Feeding

Leaving dry food out all day for cats to eat whenever they want is a major cause of obesity. In the wild, cats are “small, frequent meal” hunters, but when the bowl is never empty, many cats just keep eating.

Switching to scheduled, portioned meals (2-3 times a day) helps a lot.

Indoor Lifestyle

Indoor cats are far less active than outdoor cats, naturally burning fewer calories. With not much to do all day, some cats eat out of boredom.

More play, vertical space and puzzle feeders keep a cat moving, and a busy cat is less likely to snack out of boredom.

Owner Underestimation

Owners typically rate their cat’s body condition 1-2 points lower (better) than veterinarians do. When “slightly chubby” passes for “normal,” the extra weight goes unnoticed.

In the clinic, when the vet tells an owner their cat is overweight, many owners are reluctant to accept it at first; loving food just seems like an animal’s nature. The vet looks at both the weight and the body shape, then asks the owner to manage the diet, sometimes switching to a prescription weight-management food.

How to Help Your Cat Maintain a Healthy Weight

Dietary Adjustments

• 2-3 measured meals a day, not free-feeding
• Wet food where you can. It’s higher in protein, lower in carbs, and its 70-80% water helps cats feel full
• Ask your vet about your cat’s daily calorie target
• Keep treats under 10% of daily calories

Increase Activity

• At least 15-20 minutes of interactive play daily, with wand toys and toys your cat can pounce on (finish a laser pointer session on something she can actually catch)
• Use puzzle feeders so your cat “hunts” for meals
• Provide cat trees and vertical spaces
• In multi-cat homes, put out enough bowls, water and resting spots so stress doesn’t drive eating

Weight Loss Rate

Weight loss works best with your vet guiding it, especially for cats at BCS 8-9.

When to See the Vet

Take your cat to the vet if:

• BCS reaches 7 or higher
• Weight has increased or decreased significantly in a short time
• You’re already controlling food and the weight keeps going up
• You’re unsure what your cat’s ideal weight should be
• You want to start a weight loss plan

Your vet will first check whether another illness, such as a thyroid problem, is behind the weight change, then help you plan a diet that fits your cat.

Tracking Weight Changes

A single weigh-in doesn’t tell you much. Weigh every 2-4 weeks and write it down, and changes show up early.

Frequently Asked Questions

How do I know if my cat is overweight? Use the Body Condition Score. Feel the ribs, look at the waist from above, and check the belly from the side. If you can’t feel the ribs without pressing, there’s no visible waist, or the belly sags, your cat is probably at BCS 7 or higher, which is worth discussing with your vet.

How fast can a cat safely lose weight? Slowly: 0.5-2% of body weight per week, so a cat that needs to lose 1 kg takes about 3-6 months. Losing weight too fast can cause hepatic lipidosis (fatty liver), which can be fatal.

Do indoor cats get fat more easily? Yes. Indoor cats move less, and some eat out of boredom. Scheduled meals, puzzle feeders and daily play all help.

Get in the habit of feeling the ribs and checking the waist and belly every so often, and aim for BCS 5. If your cat is already over, start with the food and some extra play, and go slowly.