People usually find themselves here after a blunt weigh-in at the vet, a photo that shows a widening waist, or a quiet change at home: a cat that no longer jumps up, grooms properly, or plays for long. Extra weight can creep on so slowly it feels like “just getting older”, yet it raises the odds of painful arthritis and metabolic disease, and it can make anaesthesia and surgery harder to manage.2, 4
Cat weight loss needs a steady hand. Fast restriction can backfire in a way that’s uniquely feline, so the safest path is a vet-guided plan built on measured meals, careful treat control, and small bursts of daily hunting-style play.2, 3, 4
What counts as overweight in cats
Most vets don’t judge weight by the number on the scales alone. They combine:
- Body weight (tracked over time, ideally on the same scale)
- Body Condition Score (BCS), a hands-on and visual check of fat cover and body shape
- Muscle condition, because older cats can lose muscle even as they gain fat
A widely used guide is the 9-point BCS system, where an ideal score is usually around 4–5/9. Your vet clinic will often use a consistent chart (such as the WSAVA tools) so progress is comparable from visit to visit.1, 5
As a rough rule, many veterinary sources describe cats as overweight at about 10–20% above ideal weight and obese at more than 20% above ideal.4, 6
Why cats gain weight (and why it’s rarely just “too much kibble”)
Energy in, energy out
Obesity happens when energy intake stays higher than energy use for long enough. In indoor cats, the gap can be small but persistent: a few extra biscuits, a generous handful poured by eye, a second household member “topping up”, and long quiet afternoons spent sleeping rather than stalking.6
Neutering, age, and a slower metabolism
Neutering is a recognised risk factor for weight gain, and middle-aged cats are commonly over-represented in obesity statistics. As cats age, activity and lean muscle often decline, so their calorie needs can drop even if their appetite doesn’t.4, 6
Feeding style: “free feeding” makes portions invisible
Leaving a bowl out all day makes it hard to know what your cat is truly eating, especially in multi-cat homes. It also removes the natural rhythm of hunt–eat–rest that many cats respond to. Several veterinary sources flag free feeding as a common contributor to feline weight gain.2
Medical causes and medicines (less common, but important)
Most overweight cats are not overweight because of a single underlying disease, but some medical conditions and medicines can contribute. If weight gain is sudden, or your cat is hungry all the time, lethargic, vomiting, drinking more, or losing muscle, a vet check matters.6
Health risks linked to obesity in cats
Extra fat isn’t inert padding. It changes how the body handles sugar, stresses joints, and makes daily movement harder.
Diabetes and metabolic strain
Obesity increases the risk of insulin resistance and diabetes mellitus in cats, particularly in indoor and middle-aged cats.2, 4
Arthritis and reduced mobility
More weight means more load through hips, knees, elbows, and spine. In cats, that often shows up as subtle lifestyle changes: no longer jumping to favourite spots, hesitating on stairs, or playing in shorter bursts.2, 4
Lower quality of life
Overweight cats may struggle to groom properly or move as freely, which can affect coat condition and comfort. Welfare organisations also note obesity’s link with reduced quality of life and shorter life expectancy in pets.2, 7
A serious caution: rapid weight loss and fatty liver disease
Cats are unusually vulnerable to hepatic lipidosis (fatty liver disease) when they stop eating or lose weight too quickly. This is one reason “crash diets” are risky in cats, and why weight loss should be planned and monitored rather than improvised.2, 3
Quick at-home check: is my cat carrying extra weight?
Home checks don’t replace a vet assessment, but they can tell you whether it’s time to book in.
- Ribs test: You should be able to feel ribs under a light fat covering. If you have to press firmly to find them, your cat may be overweight.
- Overhead view: An obvious waist behind the ribs is a good sign. A straight-sided or rounded outline suggests extra fat.
- Side view: A tucked-up belly is typical. A sagging belly and no abdominal tuck can indicate excess fat.
If you’re unsure, ask your vet to show you your cat’s BCS and what “ideal” feels like under your hands. It’s a simple skill that makes portion decisions far more accurate at home.1, 8
Prevention: keeping a healthy cat at a healthy weight
Use regular vet check-ups as a quiet early-warning system
Small weight gains are easier to reverse than large ones. Routine visits let your vet track trends and adjust feeding before the extra kilos become the new normal.5
Measure food; don’t “pour and hope”
Portion control works best when it’s literal:
- Feed measured meals rather than leaving food out all day.
- Count treats as part of the day’s intake.
- If multiple people feed the cat, use a simple feeding chart to avoid double serves.
Food packet guides are a starting point, not a promise. Your cat’s ideal portion depends on age, activity, and whether they’re desexed.8, 9
Build movement into the day (in short, cat-sized bursts)
Cats tend to exercise like ambush predators: brief, intense effort followed by rest. Encourage that pattern with:
- 2–3 short play sessions daily with a wand toy, feather teaser, or a tossed toy to chase
- Food puzzles to slow eating and add “work” to meals
- Vertical space (a sturdy cat tree or shelves) to promote climbing and jumping
The aim is not exhaustion. It’s repetition: a few minutes here and there, most days, for the long haul.
Managing obesity: a safe, practical weight-loss plan
Step 1: start with a vet check
Before changing food, book a visit. Your vet can:
- confirm your cat’s current BCS and an estimated healthy target weight
- screen for medical issues that affect weight or appetite
- set a safe rate of weight loss and a calorie target
This matters because cats should lose weight gradually, not suddenly.2, 3
Step 2: change feeding structure before changing everything else
Many cats slim down with simple, consistent rules:
- Stop free feeding and move to set meal times.
- Weigh or measure every serve so the plan is repeatable.
- Make treats rare and tiny, or swap them for play, pats, and brushing.
In multi-cat homes, feed cats separately so the overweight cat can’t quietly finish everyone else’s leftovers.
Step 3: choose a diet that supports weight loss without muscle loss
Weight-loss diets for cats are usually designed to reduce calories while maintaining adequate protein and essential nutrients. Avoid DIY restriction that simply halves a standard diet, as it can lead to nutrient shortfalls or encourage your cat to beg and scavenge.5, 9
Step 4: increase activity in ways your cat will actually do
Start where your cat is. For an overweight cat, five minutes of chasing a toy can be plenty at first. Build slowly. Make the house do some of the work: hide small portions in puzzle feeders, place food a short distance away from sleeping spots, and use climbing options to turn everyday movement into gentle exercise.
Step 5: monitor progress (without turning life into a spreadsheet)
Weigh-ins help you see trends that are hard to spot day to day. Home weighing can work well (a baby scale is often easier than a bathroom scale). Track weight regularly and keep an eye on BCS changes, not just the number.2, 5
Contact your vet promptly if your cat stops eating, seems unwell, or is losing weight faster than planned, as cats can develop serious complications when intake drops suddenly.3
Final thoughts
Feline obesity is common, but it isn’t inevitable. A healthy weight looks ordinary: ribs you can feel, a waist that still exists, and a cat that moves through the house with quiet competence. With measured meals, fewer calories from treats, and daily play that mimics hunting, most cats can return to a safer body condition—slowly, steadily, and with their liver protected along the way.2, 3
References
- World Small Animal Veterinary Association (WSAVA) – Global Nutrition Guidelines (resources include body condition scoring tools)
- Cornell Feline Health Center (Cornell University) – Obesity in cats
- MSD Veterinary Manual (Professional) – Metabolic diseases affecting the liver in small animals (includes hepatic lipidosis context)
- MSD Veterinary Manual (Professional) – Obesity (definition, risk factors, health risks)
- WSAVA Nutritional Assessment Guidelines (peer-reviewed article via PubMed Central)
- PetMD (veterinarian-authored/reviewed) – Obesity in cats: signs, causes, and treatment
- RSPCA Pet Insurance (Australia) – Signs of pet obesity and tips
- Agriculture Victoria – Code of Practice for the Private Keeping of Cats (nutrition guidance and body condition checks)
- US FDA (Animal Health Literacy) – Summary of AAHA nutritional assessment guidelines (BCS/MCS systems and ideal BCS ranges)
Veterinary Advisor, Veterinarian London Area, United Kingdom