Roughly speaking, if you cannot feel your cat's ribs without pressing, the cat is carrying too much fat. Feline obesity is not cosmetic. It raises the risk of diabetes, arthritis, urinary disease, skin problems, and anaesthetic complications, and it shortens lifespan. It is also fixable — but the fix has one hard rule that owners get wrong constantly: weight loss in cats must be slow. A cat that loses weight fast, or stops eating altogether, can develop hepatic lipidosis, which is far more dangerous than the extra weight.

Is the cat actually overweight?

Use body condition score rather than the scale alone. On the common nine-point scale, 4 to 5 out of 9 is ideal: ribs felt easily under a thin fat layer, a visible waist behind the ribs when viewed from above, and a slight abdominal tuck from the side. At 6 the ribs are hard to feel and the waist is gone. At 7 to 8 there is a fat pad on the belly and the back looks broad. At 9 the abdomen is distended and the cat cannot groom properly. Weigh the cat monthly on a baby scale or at the clinic, and record it — trends matter more than any single number. A large-framed cat at 6 kg may be ideal, while a small cat at 6 kg may be obese.

Why it matters more than owners think

Fat tissue is metabolically active, not inert storage. In cats it drives insulin resistance, which is the road to diabetes; some diabetic cats go into remission once they lose weight on a high-protein diet. Extra load accelerates arthritis, which reduces movement, which adds more weight. Obese cats are at higher risk under anaesthesia, are worse at grooming, and more often develop urinary and skin problems. Overweight cats also have a markedly higher risk of hepatic lipidosis if they stop eating for any reason, which makes every illness more dangerous.

The safe rate of loss

Aim for about 0.5 to 1 percent of body weight per week. Many veterinary guidelines allow up to 2 percent, but slower is safer and better tolerated. For a 6 kg cat, that is roughly 30 to 60 grams a week. A faster drop, a sudden refusal to eat, or a diet that cuts intake by half is how cats end up with fatty liver. Never fast a cat for weight loss. Never use a "diet" that provides less than about 60 percent of the resting energy requirement without veterinary supervision.

Doing the maths

Resting energy requirement (RER) is calculated as 70 × (body weight in kg)^0.75. For a 6 kg cat that is about 240 kcal a day at current weight. A weight-loss plan typically feeds 60 to 80 percent of the RER calculated for the target weight, not the current weight, and your vet will set the exact figure. Then weigh the food in grams with a kitchen scale — cups vary enormously, and "one scoop" is how most plans quietly fail. Count treats, including the ones from other family members, and cap them at about 10 percent of daily calories. Recheck weight every two weeks and adjust by 10 percent if loss has stalled for three weeks.

What to feed, and how

Wet food helps: it is less calorie-dense per gram, has higher water content, and is more satisfying in volume. A high-protein, low-carbohydrate wet diet preserves muscle and improves satiety. If you feed dry, weigh it and consider a therapeutic weight-loss formula, which is formulated to provide adequate protein and nutrients in a smaller calorie load — ordinary "light" foods can under-supply protein. Stop free-feeding entirely; split the daily ration into at least three meals. Use a puzzle feeder or a scatter feed to slow eating. If there are multiple cats, feed them in separate rooms, because the slim cat will finish the fat cat's portion.

Exercise, gently

Obese cats do not exercise, and forcing them will not work. Build activity in short bursts: two or three sessions of five minutes with a wand toy, a laser pointer finished on a real toy so the cat gets to catch something, or food hidden around the room. Put food bowls upstairs, or move them between meals. Cat trees and vertical space encourage movement more than most owners expect. Start with what the cat will actually do, then add a minute a week. Weight loss is mostly about intake — exercise is a supporting act, not the main one.

When to see a vet

  • Unplanned weight loss, especially with a good or increased appetite.
  • Weight loss with vomiting, diarrhoea, or increased thirst and urination.
  • Yellow gums or ear leather, drooling, or sudden weakness — possible hepatic lipidosis.
  • A cat that refuses food for more than 24 hours during a diet.
  • You need a calorie target, and the cat has diabetes, kidney disease, or arthritis.
  • A kitten, pregnant cat, or senior cat that you think is overweight — do not diet these at home.

Keeping it off

Most cats regain the weight, usually because portions creep back up and treats return. Pick a maintenance calorie figure at the target weight, keep weighing food, and keep the monthly weigh-in for at least a year after reaching the goal. Two useful habits: measure the daily ration into a container each morning and feed only from it, and photograph the cat from above once a month — the waist is easier to see in a photo than in the mirror. If your cat lives with someone else, agree on the rules together, because a second feeder undoes a plan faster than anything else. For feeding routines and enrichment, see care, and for weight-related disease, health.

This is general information, not a diagnosis.

Frequently asked

How fast can a cat safely lose weight?

About 0.5 to 1 percent of body weight per week, which is roughly 30 to 60 grams for a 6 kg cat. Fasters losses increase the risk of hepatic lipidosis and muscle loss, so slow and steady with regular weigh-ins is the safer approach.

Can I just feed less of my cat's normal food?

Cutting portions of a maintenance diet often cuts protein and nutrients along with calories. A therapeutic weight-loss diet, ideally wet and high in protein, lets you reduce calories while meeting nutritional needs. Ask your vet for a target calorie figure first.

My cat is overweight but refuses to play. What can I do?

Start with food-based enrichment rather than forced exercise: scatter feeding, puzzle feeders, and hiding kibble around the room. Add short two-minute wand sessions and stop while the cat is still interested. Movement increases naturally as weight comes down and joints hurt less.