How to keep your cat's weight healthy

Keeping a cat at a healthy weight is one of the simplest things you can do to help them live a longer, more comfortable life. Weight tends to creep on gradually, a little extra biscuit here, an extra pouch there, and most owners don't notice until a vet or a friend points it out. The good news is that your cat's shape is something you can check yourself, at home, in a couple of minutes.

This guide covers how to assess your cat's body condition, how much you should actually be feeding them, and how to help an overweight cat slim down safely, without crash diets or guesswork. As with any change to your cat's routine, your vet should be your first port of call if you're worried about their weight, especially before starting a weight-loss plan.

None of this is about obsessing over the scales. It's about spotting the signs early, feeding the right amount for your individual cat, and knowing what safe, steady weight loss actually looks like if your cat does need to lose a bit.

How to check your cat's body condition score

Vets use a body condition score (BCS) to judge whether a cat is underweight, ideal, or overweight, usually on a nine-point scale, and you can do a simplified version of the same check at home. According to PDSA, run your hands gently over your cat while checking the following:

• Ribs – the skin should move freely over them, and you should be able to feel each rib with only a light touch, without pressing hard.
• Spine and hip bones – you should be able to feel these under the skin, but not see them sharply.
• Tail base – there shouldn't be a noticeable pad of fat where the tail meets the body.
• Waist – looking down from above, your cat should have a visible waist behind the ribs, not a straight or bulging outline.
• Tummy tuck – viewed from the side, the belly should tuck up behind the ribcage rather than hang or bulge.

A cat in ideal condition sits around the middle of the nine-point scale: ribs easily felt with a slim covering, a clear waist, and a tucked tummy. If you can't feel the ribs without pressing firmly, can't see a waist, and the belly sags or bulges, your cat is likely carrying excess weight. Weigh your cat regularly if you can, ideally monthly, so you catch gradual changes before they become a bigger problem.

What counts as overweight or obese

It's worth knowing that "overweight" and "obese" are specific terms, not just a general description. Cats Protection defines a cat as overweight once they're more than 10% above their ideal body weight, and obese once they're more than 20% above it. The tricky part is that "ideal weight" isn't one fixed number for all cats, it depends on your individual cat's frame, breed and build, which is why a hands-on body condition check (rather than the number on a scale alone) is so useful, and why your vet is best placed to confirm what your particular cat should weigh.

This isn't a niche problem. PDSA reports that over a third of cats in the UK are overweight, which makes it one of the most common health issues seen in general practice. If your cat's body condition score comes back high, it doesn't mean you've failed, it just means it's time for a plan.

Why the extra weight matters

Extra weight isn't just cosmetic. According to the RSPCA, carrying too much body fat has a direct, negative impact on a cat's health, welfare and quality of life, and both the RSPCA and PDSA link feline obesity to a longer list of serious conditions, including:

• Diabetes
• Arthritis and joint problems, from the additional strain on joints
• Bladder and urinary issues
• Liver disease, including a serious condition called hepatic lipidosis
• Breathing difficulties, which PDSA notes can be worse in flat-faced breeds
• Certain cancers
• Reduced ability to groom themselves properly, and reduced general mobility

Overweight cats face a greater risk of diabetes, arthritis, urinary problems and breathing difficulties, and carrying excess weight can shorten a cat's life.

On top of the specific conditions, extra weight puts ongoing strain on a cat's heart, lungs and joints every single day, which is why getting on top of it sooner rather than later makes such a difference to their comfort and lifespan.

What causes cats to gain weight

In most cases, the cause is straightforward. PDSA puts it plainly: most overweight cats are simply eating more than they need. Modern life doesn't help, indoor cats in particular tend to be less active than cats with outdoor access, and free access to a full bowl makes it easy to overeat without anyone noticing.

That said, it's not always just about food quantity. PDSA notes that some medical conditions, such as heart disease or arthritis, can reduce a cat's activity levels and contribute to weight gain, which is one reason a vet check is worthwhile before starting any diet. In unneutered female cats, it's also worth ruling out pregnancy if there's a sudden change in body shape. Age plays a role too: cats tend to become less active as they move from young adulthood into middle age, so the portions that suited them as a lively two-year-old may simply be too much a few years later.

Getting portions right

This is where most weight problems start, and where most of the fix lies. A few practical points from PDSA and VCA Animal Hospitals:

• Feed for their ideal weight, not their current weight. If your cat needs to lose weight, their portions should be calculated for the body weight you're working towards, under vet guidance, not simply a slightly smaller version of what they eat now.
• Split the daily allowance into several small meals rather than one or two large ones, which PDSA recommends as it suits cats' natural grazing behaviour better than large single meals.
• Measure by weight, not by eye. VCA specifically recommends using a kitchen gram scale rather than a measuring cup, since cup measurements for dry food can vary considerably and lead to consistent overfeeding.
• Budget for treats. VCA suggests treats should make up no more than around 10% of a cat's daily calories, and any treats given should be subtracted from the day's food allowance, not added on top.

Our Pet Calorie Calculator can help you get a general sense of your cat's daily energy needs, though your vet's figure, based on your cat's exact target weight, is the one to build a proper diet plan around.

Choosing the right food for weight loss

If your cat needs to lose a meaningful amount of weight, simply cutting down their usual food isn't always the safest approach. VCA explains that dedicated weight-loss diets, whether from your vet or an over-the-counter "light" range, are formulated to be lower in calories while remaining higher in protein and fibre, so your cat feels satisfied on fewer calories rather than just hungry all day.

When you do change food, transition gradually, VCA recommends introducing a new diet over two to three weeks, mixing increasing amounts of the new food with the old, to avoid digestive upset. Cats Protection adds that many vet practices run free weight-loss clinics, which can be a genuinely useful (and free) way to get a plan tailored to your cat rather than following generic advice.

If you're ever unsure whether a particular food, treat or table scrap is safe to give your cat while they're dieting, our Can My Pet Eat This? tool is a quick way to check before you feed it.

A safe, gradual weight-loss plan

This is the part owners most often get wrong, and it matters more than almost anything else in this guide: cats must not lose weight too quickly. VCA is clear that a safe rate is roughly 1–2% of body weight per week, and that severely overweight cats may need to lose even more slowly, closer to 0.5% a week, under veterinary supervision.

The reason this matters so much is that rapid weight loss in cats, caused by sudden severe food restriction or a cat simply refusing to eat, can trigger hepatic lipidosis, a serious and potentially fatal form of liver disease, along with unwanted muscle loss. Cats Protection warns against gradually reducing the daily food allowance rather than switching to an extreme diet that drastically cuts food in one go, precisely because sudden, severe restriction can make a cat seriously unwell.

A sensible weight-loss plan, drawing on VCA's guidance, generally looks like this:

• An initial vet check to confirm ideal weight, rule out underlying illness, and set a calorie target
• A follow-up weigh-in around a week after starting the new feeding plan
• Another check once the diet transition is complete, usually one to two weeks later
• Ongoing weigh-ins at least every couple of weeks until the target weight is reached, with monthly vet reviews if you're weighing at home in between

Exercise, play and enrichment

Food isn't the only side of the equation. PDSA highlights exercise as an essential part of weight management, particularly for indoor cats who don't get the natural activity of an outdoor territory to patrol. Regular, short play sessions with a wand toy or ball, little and often, help burn calories and keep joints and muscles in good condition.

Puzzle feeders are another tool both Cats Protection and PDSA recommend: instead of a bowl of food appearing on demand, your cat has to work a little to release each piece of kibble, which slows down eating, adds mental stimulation, and turns mealtimes into a form of exercise in their own right. You can buy purpose-made puzzle feeders or make simple versions at home from empty containers with holes cut into them.

Multi-cat households

Dieting one cat in a multi-cat household brings its own challenges, mainly because a dieting cat can simply help themselves to a housemate's bowl. Both PDSA and Cats Protection recommend feeding cats in separate spaces so the cat on a diet can't access anyone else's food, and microchip-activated feeders, which only open for the chip of the cat they're programmed for, can be a genuinely effective solution where free access is the problem.

It's also worth remembering that competition or stress around shared feeding areas can itself drive overeating, so giving each cat their own calm, separate space to eat isn't just about portion control, it can reduce food-related stress for the whole household.

Common mistakes to avoid

A few pitfalls come up again and again when owners try to help a cat lose weight:

• Starving or drastically cutting food overnight. As covered above, this risks serious illness rather than speeding up results.
• Measuring food by eye or by cup instead of weighing it, which almost always leads to overfeeding.
• Forgetting treats and scraps count. A few biscuits or a taste of dinner here and there can undo a carefully calculated daily allowance.
• Giving in to begging, especially in multi-cat homes where a dieting cat has learned that persistence gets results.
• Not re-weighing regularly. Without regular check-ins, it's easy to miss a plan that's working too slowly, or too fast.
• Changing food too abruptly, which can cause digestive upset and put owners off continuing with a new diet.

When to see your vet

Speak to your vet before starting any weight-loss plan for your cat, not just afterwards. They can confirm your cat's ideal weight, check for underlying conditions that might be contributing to weight gain or making activity harder, and calculate a safe calorie target and expected rate of loss for your individual cat.

You should also contact your vet urgently if a cat on a diet, or any overweight cat, stops eating or eats noticeably less for more than a day, since this can be a sign of the liver condition hepatic lipidosis, which is a particular risk in overweight cats and needs prompt treatment. Many practices run free weight-loss or nurse clinics, which are a good way to get regular, supported check-ins without always needing a full vet appointment.

*This is general guidance, not a substitute for advice from your vet, who can assess your individual pet.*

Sources

• PDSA — how to body condition score your cat (pdsa.org.uk).
• PDSA — obesity in cats: causes, risks and treatment (pdsa.org.uk).
• RSPCA — pet obesity: causes, treatment and prevention (rspca.org.uk).
• Cats Protection — cat obesity advice (cats.org.uk).
• Cats Protection — how can I help my cat lose weight? (cats.org.uk).
• VCA Animal Hospitals — creating a weight reduction plan for cats (vcahospitals.com).