How do I tell if my cat is overweight?

The body condition score (BCS) system is the standard method. Run your hands along your cat's ribcage — you should be able to feel each rib without pressing, but not see them. From above, your cat should have a visible waist behind the ribs. From the side, the belly should be tucked upward slightly rather than hanging. The WSAVA body condition score chart provides illustrated reference points, and your vet can confirm at a check-up.

How much should I reduce food if my cat is overweight?

A 10–15% reduction in daily calories is the recommended starting point for overweight (BCS 6–7/9) cats. Weigh the amount precisely using a kitchen scale rather than estimating by eye or using a scoop. Reassess after four weeks — aim for 0.5–1% of body weight loss per week. Use our feeding calculator and how much to feed guide to establish a baseline.

Is my neutered cat more likely to gain weight?

Yes. Neutering reduces energy expenditure by approximately 25–30% due to hormonal changes affecting metabolism. The same amount of food that was appropriate before neutering will cause weight gain afterward. Adjust portions down by 20–25% immediately following neutering, or switch to a lower-calorie neutered-cat formula.

Can rapid weight loss be dangerous for cats?

Yes — this is one of the most important things to understand. Rapid weight loss in overweight cats, especially if they stop eating, can trigger hepatic lipidosis (fatty liver disease), a serious and potentially fatal condition. Weight loss should be gradual and supervised. Never put a cat on a crash diet or very low-calorie food without vet guidance. See our hepatic lipidosis glossary entry for more detail.

Cat Obesity Study 2026: Over Half of UK Cats Are Overweight

What the 2026 data shows

The PDSA Animal Wellbeing (PAW) Report — published annually since 2011 — surveys over 5,000 UK pet owners and draws on clinical data from PDSA veterinary practices. The 2026 edition documents a continued upward trend in feline obesity prevalence:

52%

of cats seen by UK vets in 2026 are overweight or obese

+8pp

increase since 2020 (from 44%)

78%

of overweight cats are fed primarily dry food, per the study cohort

Why cat obesity is increasing

The report identifies several interacting factors behind the trend:

Increasing proportion of indoor-only cats: Indoor cats have lower energy expenditure than outdoor cats. The energy requirements of an indoor neutered cat are roughly 70–80% of an intact outdoor cat of the same weight, yet feeding amounts are often not adjusted accordingly.
Free-feeding of calorie-dense dry food: Many owners leave a full bowl of dry food available throughout the day. Dry food is significantly more calorie-dense per gram than wet food — a small overestimate in portion size compounds quickly.
Post-neutering adjustment failure: Neutering reduces metabolic rate by an estimated 25–30%, but most owners do not reduce food portions after the procedure.
Treat calories not counted: 67% of owners surveyed gave treats daily; fewer than 20% said they accounted for treat calories in the day's total food allowance.

Health consequences of obesity in cats

Obesity in cats significantly increases risk for:

Type 2 diabetes mellitus — insulin resistance linked to adipose tissue accumulation
Osteoarthritis — mechanical load and inflammatory effects of adipose tissue accelerate joint degeneration
Hepatic lipidosis — especially if an obese cat stops eating suddenly; fat mobilises faster than the liver can process it. See our hepatic lipidosis glossary entry for more detail.
Urinary tract disease — increased risk of feline idiopathic cystitis and struvite crystals
Reduced lifespan — studies consistently show 1.5–2 year reduction in median lifespan for obese cats versus ideal-weight cats

What owners can do

The starting point is knowing your cat's current body condition score and adjusting daily calorie intake accordingly. The WSAVA's body condition scoring system — illustrated in the WSAVA Global Nutrition Guidelines — is freely available and takes less than a minute to apply.

For the calculation method, use our feeding calculator and read the full guide on how much to feed your cat. Transitioning from dry-only to mixed wet and dry feeding reduces calorie density and increases satiety for many overweight cats.

If your cat needs structured weight loss, involve your vet — rapid unsupervised weight loss in cats carries its own serious risks, and a target loss rate, progress monitoring schedule, and appropriate prescription diet (if needed) make outcomes significantly better.

Cat obesity study 2026: over half of UK cats are overweight

What the 2026 data shows

Why cat obesity is increasing

Health consequences of obesity in cats

What owners can do

Frequently asked questions