Obesity is one of the health conditions that cats owners should know about, because it affects quality of life, and it is easier to manage when it is caught early. This guide explains what obesity is, the signs to watch for, what causes it, how it is diagnosed, how it is treated, whether it can be prevented, and how to live with a cat that has it. Every suggestion here is general guidance, not a prescription for an individual cat.
Senior cats are the focus of this guide. A cat is usually considered a senior from about 11 years, and geriatric from 15, and from that age vet checks should move to twice a year, with weight, teeth, and kidneys checked each time. obesity is more common in older cats than in young ones, and it is often harder to spot in a senior, because its signs — stiffness, slowing down, weight loss, confusion — are easily mistaken for normal ageing. The rest of this guide covers the condition itself, with the senior years in mind throughout.
What is obesity in cats?
Obesity is a condition where a cat carries so much extra fat that its health is affected — not just a little extra weight, but enough fat to strain its joints, its heart, and its metabolism, and to shorten its life. A cat is usually called obese when it is more than about 20% above its ideal weight, and overweight when it is 10 to 20% above it. Obesity is the most common nutrition-related health problem in cats, and it is also one of the most preventable: it comes from taking in more calories than the cat burns, over months and years.
The rest of this guide covers the signs, the causes, how obesity is diagnosed, how it is treated, whether it can be prevented, and how to live with a cat that has it. A cat with obesity should be checked by a vet, because the right treatment depends on the individual cat, its age, and how advanced the condition is — and because some of the signs of obesity can also be signs of other conditions, which need a vet to tell apart. The cat ideal weight calculator works out a target weight range, and the when is a cat considered a senior guide gives the senior thresholds by size.
Signs of obesity in cats
The signs of obesity in cats are listed below. Not every cat with obesity will show every sign, and some cats will show only one or two — but any one of these signs, especially if it lasts more than a few days or gets worse, is worth mentioning to a vet. A cat that is bright, eating, drinking, and otherwise well between episodes is less likely to be seriously ill than a cat that is lethargic, off its food, or losing weight — but the only way to know is to check.
- You cannot feel the ribs easily — you have to press hard to find them under a layer of fat.
- There is no waist when you look down at the cat from above.
- There is no tummy tuck when you look from the side — the belly hangs low or sags.
- The cat tires easily on walks or in play, and pants more than it used to.
- The cat struggles to jump, climb stairs, or get up after lying down.
- The collar or harness needs letting out, or the cat has outgrown it.
- The cat begs for food constantly, and is always looking for more.
If two or more of those signs apply, or if one sign is severe — a cat that cannot urinate, cannot breathe, cannot stand, or has had a seizure lasting more than five minutes — see a vet the same day. Those are signs that need a vet, not waiting. Bring a note of when the signs started, how often they happen, and what the cat eats and drinks — that information helps the vet far more than a guess about the cause. The how to tell if your cat is overweight guide gives the hands-on check for weight, which matters for many of these conditions.
Causes and risk factors for obesity
Obesity usually comes from the same two causes: too much food and too little exercise. Treats, table scraps, and food from other pets' bowls add up fast, and a cat that is fed by eye rather than by measure is almost always fed too much. Neutering cuts calorie needs by about 10 to 20%, and a cat whose food is not cut after the operation will gain weight. Age matters too: an older cat moves less but often eats the same amount, so weight creeps up. Some breeds gain weight more easily, and some medical conditions, such as an underactive thyroid in dogs, cause weight gain — but food and exercise are the main causes in most cats.
Some cats are more prone to obesity than others, because of their genes, their breed, their size, or their age — but breed and age are not destiny, and a cat of any breed can develop obesity. What an owner can control is weight, food, exercise, and vet checks: a cat at a healthy weight, with measured food and daily exercise, is less likely to develop obesity and will cope better with it if it does. A cat that is overweight, that eats a poor diet, or that never sees a vet is more likely to develop obesity and to have it found late, when it is harder to treat.
How obesity is diagnosed
A vet diagnoses obesity with a weigh-in and a body condition score, on the nine-point scale where 4 to 5 is ideal and 8 to 9 is obese. The vet will feel the ribs, look for a waist from above and a tummy tuck from the side, and compare the weight with the breed's typical range. The vet may also run a blood test, because some medical conditions cause weight gain, and those need treating, not just less food. A cat that is obese should have a plan set with its vet, because a crash diet is dangerous — especially for cats.
If you are worried about your cat, see a vet and mention obesity by name, with the signs you have seen and when they started. Bring a note of what the cat eats, how much, and any medicines it takes, and whether it has had obesity or a related condition before. A video of the signs, if it is safe to take one, helps the vet far more than a description — especially for seizures, limping, or breathing problems. Do not try to diagnose obesity yourself, and do not buy medicines or special diets for it without veterinary advice, because the wrong treatment can make it worse.
Treatment and management of obesity
Treatment is slow, steady weight loss: measured food, a little more exercise, and a monthly weigh-in. A commonly cited safe target is about 1% of body weight per month for dogs and about half a percent to 1% for cats. A weight-loss food helps, because it carries fewer calories per mouthful, less fat, more fibre so the cat feels full, and enough protein to hold muscle. Treats should stay under 10% of daily calories, and exercise should build up gradually — short, frequent walks or play sessions rather than one long hike, because a heavy cat that is suddenly asked to run will strain its joints. In some cases the vet may prescribe a medicine, but food and exercise are the core of it.
Treatment is a decision made with the vet, weighing the cat's age, health, and quality of life against the treatment and its side effects. Some owners choose not to treat, and to keep the cat comfortable instead — and that is a valid choice, made with the vet, not on the basis of a web page. Whatever is decided, the treatment must be followed every day, at the same times, and the cat must be checked regularly, because obesity changes over time, and the treatment needs to change with it. Do not stop a medicine suddenly, and do not change the dose without veterinary advice.
Living with a cat with obesity
A cat that is obese can live a full and happy life once the weight comes off — and even a small weight loss, of 5 to 10% of body weight, makes a real difference to joints and health. Keep the food measured, keep treats under 10% of daily calories, keep exercise daily, and keep weighing monthly for life. A cat that has lost weight needs less food than it did before, because a lighter cat burns fewer calories, so do not go back to the old amount once the target is reached. Watch for the health problems that obesity brings — joint pain, diabetes, and heart disease — and mention any change to your vet promptly.
Keep a routine: the same times for food, medicines, walks, and play, the same places for furniture, food, and water, and a calm, predictable home. Keep a note of appetite, drinking, weight, and behaviour, and mention any change to the vet promptly — a change that lasts more than a few days, or that gets worse, is worth a vet visit. Keep the cat at a healthy weight, with measured food and daily exercise at a level that suits its body, and keep vet checks regular: once a year as an adult, and twice a year as a senior. The senior cat diet guide covers feeding older cats, and the cat calorie calculator works out daily calories for any weight.
Senior care for a cat with obesity
A senior cat with obesity needs more care than a young one: twice-yearly vet checks, a diet review, and attention to weight, teeth, and kidneys. Keep the cat moving every day, at a level that suits its body — shorter, more frequent walks or play sessions, and play that does not strain stiff joints. Give it a warm, supportive bed, ramps or steps instead of jumping, and a predictable routine, with furniture, food, and water in the same places. Mention any change to your vet promptly, because a senior cat that suddenly gets worse may have a new problem, not just a bad day.
Can obesity be prevented?
Obesity is prevented by the same things that treat it: measured food, treats under 10% of daily calories, daily exercise, and a monthly weigh-in. Cut food by 10 to 20% after neutering, and watch the waistline for the next few months. Feed two meals a day at set times, not food left down all day, and agree in the household who feeds the cat and what treats are allowed, because a cat fed by three people is fed three times. Weigh monthly and write the number down: the line over months is what matters, and a cat that is slowly gaining weight needs a small food cut, before it becomes clearly overweight.
Early checks matter most: have the cat checked regularly, so obesity is found early, when treatment works best. Keep the cat at a healthy weight, with measured food and daily exercise, and mention any change in drinking, eating, weight, or behaviour to your vet early, because a change caught early is easier to treat than one left for weeks.
For related reading, see the cat ideal weight calculator, the cat body condition score chart, the how to tell if your cat is overweight guide, the senior cat diet guide, the cat calorie calculator, the when is a cat considered a senior guide.
Frequently asked questions
What is obesity in cats?
Obesity is a condition where a cat carries so much extra fat that its health is affected — not just a little extra weight, but enough fat to strain its joints, its heart, and its metabolism, and to shorten its life. A cat is usually called obese when it is more than about 20% above its ideal weight, and overweight when it is 10 to 20% above it. Obesity is the most common nutrition-related health problem in cats, and it is also one of the most preventable: it comes from taking in more calories than the cat burns, over months and years.
What are the signs of obesity in cats?
The most common signs are: You cannot feel the ribs easily — you have to press hard to find them under a layer of fat. There is no waist when you look down at the cat from above. There is no tummy tuck when you look from the side — the belly hangs low or sags. See the full list above for every sign to watch for, and see a vet promptly if two or more apply, or if one sign is severe.
What causes obesity in cats?
Obesity usually comes from the same two causes: too much food and too little exercise. Treats, table scraps, and food from other pets' bowls add up fast, and a cat that is fed by eye rather than by measure is almost always fed too much. Neutering cuts calorie needs by about 10 to 20%, and a cat whose food is not cut after the operation will gain weight. Age matters too: an older cat moves less but often eats the same amount, so weight creeps up. Some breeds gain weight more easily, and some medical conditions, such as an underactive thyroid in dogs, cause weight gain — but food and exercise are the main causes in most cats.
How is obesity diagnosed?
A vet diagnoses obesity with a weigh-in and a body condition score, on the nine-point scale where 4 to 5 is ideal and 8 to 9 is obese. The vet will feel the ribs, look for a waist from above and a tummy tuck from the side, and compare the weight with the breed's typical range. The vet may also run a blood test, because some medical conditions cause weight gain, and those need treating, not just less food. A cat that is obese should have a plan set with its vet, because a crash diet is dangerous — especially for cats.
How is obesity treated?
Treatment is slow, steady weight loss: measured food, a little more exercise, and a monthly weigh-in. A commonly cited safe target is about 1% of body weight per month for dogs and about half a percent to 1% for cats. A weight-loss food helps, because it carries fewer calories per mouthful, less fat, more fibre so the cat feels full, and enough protein to hold muscle. Treats should stay under 10% of daily calories, and exercise should build up gradually — short, frequent walks or play sessions rather than one long hike, because a heavy cat that is suddenly asked to run will strain its joints. In some cases the vet may prescribe a medicine, but food and exercise are the core of it.
When should a cat with obesity see a vet?
See a vet promptly if the cat shows any of the signs above, especially if they last more than a few days or get worse — and the same day if the cat cannot urinate, cannot breathe, cannot stand, has had a seizure lasting more than five minutes, or is lethargic or off its food. Bring a note of when the signs started and what the cat eats and drinks. A cat with obesity should be checked by a vet, because the right treatment depends on the individual cat, its age, and how advanced the condition is.
Results on this page are estimates for general information only and are not veterinary advice. If your pet is ill, underweight, overweight, pregnant, or has a health condition, consult your veterinarian before changing diet or care.