Daily calorie needs for your cat — based on RER & MER formulas
Many cats are overfed because their owners follow the feeding guides on food packaging. These guides are often set to maximise food sales and can be 20–40% above a typical indoor neutered cat's actual needs. The veterinary standard formula is:
RER (kcal/day) = 70 × (body weight in kg)^0.75
For a 4 kg neutered indoor cat: RER ≈ 166 kcal. Multiply by a life-stage factor (1.2 for indoor neutered) = ~200 kcal/day. Most packaging suggests 300–350 kcal/day for the same cat — a 50–75% overestimate.
It varies by weight and life stage. Rough guidance: 3 kg cat: ~150–180 kcal/day; 4 kg cat: ~190–230 kcal/day; 5 kg cat: ~230–270 kcal/day; 6 kg cat: ~265–310 kcal/day (if that's their ideal weight — 6 kg is overweight for most cats). Kittens need around 250–300 kcal/day as a flat amount due to growth needs. Pregnant and lactating cats need significantly more — always consult your vet for these stages.
Take your cat's daily calorie need and divide by the food's kcal content per 100g. A 4 kg indoor neutered cat needing 200 kcal/day on dry food at 370 kcal/100g: 200 ÷ 370 × 100 = 54 g/day (~3.5 tablespoons). On wet food at 95 kcal/100g: 200 ÷ 95 × 100 = 210 g/day (roughly half a standard 400g can). Always check your specific food's calorie content, as it varies considerably between brands.
Studies suggest 50–60% of cats in the US and UK are overweight or obese. The main culprits are free-feeding (leaving dry food out 24/7 allows cats to graze and overeat), following inflated package guidelines, not adjusting food after neutering, and excessive treats. Indoor cats also expend fewer calories than outdoor cats. Obesity in cats increases risk of type 2 diabetes, hepatic lipidosis (fatty liver disease), joint pain, urinary tract disease, and reduced lifespan by 2+ years.
Yes — by around 25–30%. Oestrogens and androgens boost metabolic rate, so removing them reduces calorie needs. A cat that needed 250 kcal/day before neutering may only need 175–195 kcal/day after. Many cats gain weight rapidly in the first 6–12 months post-neutering if food isn't reduced. Switch to a "neutered" or "indoor" formula cat food (lower calorie density) and reduce portions immediately after surgery, not when weight gain is already noticeable.
From a nutritional standpoint, both can be complete and balanced if they meet AAFCO or FEDIAF standards. However, wet food has advantages for most cats: it provides hydration (cats have low thirst drive and often don't drink enough when eating dry food), is more satiating per calorie (higher protein, lower carbohydrate), and may reduce risk of urinary crystals and kidney disease. Many vets recommend primarily wet food, with dry used as a supplement or for dental health. Raw food can be excellent if properly balanced — consult a veterinary nutritionist.