Feeding a Cat Over 15 in Ontario: Appetite Loss, Hyperthyroidism and Soft-Food Portions by Weight

Short answer: Most cats over 15 need roughly 60–80 kcal per kg of body weight daily — more than a middle-aged cat — split into three or four small, warm, soft meals. Feed calorie-dense pâté or shredded wet cat food, weigh your cat monthly, and get any appetite drop or weight loss checked by a veterinarian.

Bottom line: A cat past 15 usually loses weight not because she's eating too much, but because she's digesting less and eating less at each sitting. The fix is calorie density, moisture, warmth and frequency — plus bloodwork, because hyperthyroidism and kidney disease both start with the same "she's just old" symptoms.

Why does a cat over 15 need more calories, not fewer?

Cats over 12 progressively lose the ability to digest fat and protein, so they need a higher-calorie, higher-protein diet than a 7-year-old cat. Landmark work on feline ageing found that roughly one in five cats over 14 has reduced protein digestibility, and about a third show reduced fat digestibility — which is why the "senior = light formula" habit backfires badly at this age.

The American Association of Feline Practitioners classifies cats 15 and older as geriatric, a separate life stage from "senior" (11–14). Practically, that means a 4 kg (8.8 lb) geriatric cat who used to hold weight on 200 kcal a day may now need 240–280 kcal to stay at the same body condition. Meanwhile her stomach capacity hasn't grown, her sense of smell has faded, and dental discomfort may make crunching a 10 mm kibble unappealing.

Protein matters even more than calories. AAFCO sets the adult cat maintenance minimum at 26% protein on a dry-matter basis, but that's a floor for a healthy adult, not a target for a 16-year-old losing muscle mass. Most geriatric-cat nutrition research points toward 40–50% protein on a dry-matter basis to slow sarcopenia, assuming kidney values are normal. Check the guaranteed analysis on the label, and if you're unsure how to convert a wet food's 10% protein "as fed" into dry matter, our staff will do the math with you — a can at 10% protein and 80% moisture is actually 50% protein dry matter.

How much soft food should a 15-year-old cat eat per day?

Feed 60–80 kcal per kilogram of body weight daily, divided into 3–4 meals. A 3 kg cat needs roughly 180–240 kcal; a 4 kg cat 240–320 kcal; a 5 kg cat 300–400 kcal. Since most 5.5 oz (156 g) pâté cans run 130–200 kcal, that's usually 1.5–2.5 cans a day.

Here's how that translates once you look at real portions. Always confirm the kcal/can figure on your specific product, because it varies enormously between a broth-style can and a dense pâté:

• 2.5–3 kg (5.5–6.6 lb) cat — 180–240 kcal/day; about 1 to 1.5 standard 5.5 oz cans, or 4–5 of the small 2.8 oz cans.
• 3.5–4 kg (7.7–8.8 lb) cat — 220–320 kcal/day; roughly 1.5 to 2 standard cans split across four meals of 60–80 kcal each.
• 4.5–5 kg (10–11 lb) cat — 280–400 kcal/day; 2 to 2.5 standard cans, often easier to hit by topping meals with freeze-dried protein.
• 5.5–6 kg (12–13 lb) cat — 340–480 kcal/day; 2.5 to 3 cans, though a cat this size at 15 is more likely overweight than underweight, so ask your vet before increasing.

Weigh your cat, don't eyeball her. A digital kitchen or baby scale accurate to 10 g is enough. Losing 5% of body weight — just 200 g on a 4 kg cat — is a veterinary appointment, not a food-brand problem.

What causes appetite loss in a very old cat?

Appetite loss in a cat over 15 is a symptom, not a preference. The most common drivers are dental disease and painful resorptive lesions, chronic kidney disease, hyperthyroidism, hypertension, arthritis that makes bending to a floor-level bowl uncomfortable, constipation, and a reduced sense of smell that makes cold food smell like nothing at all.

The AVMA recommends twice-yearly wellness exams for senior and geriatric pets, and full bloodwork plus a total T4 is the standard senior panel your veterinarian will run. Get that done before you spend a month rotating flavours. In our store we see customers who've bought eight different cans trying to tempt a cat who actually had a fractured carnassial tooth — no recipe fixes that.

Once medical causes are managed, the mechanics of serving matter more than most owners expect. Cats detect food largely by aroma, and aroma volatilizes with heat. Elevate the bowl 8–10 cm so an arthritic neck isn't hyperextended. Use a wide, shallow ceramic dish so whiskers don't touch the sides. And throw out uneaten wet food after 30 minutes — a geriatric cat learns fast that the food bowl smells stale.

Why is my senior cat suddenly not eating?

Sudden anorexia in a cat over 15 is an urgent sign. Cats can develop hepatic lipidosis after just 2–3 days without adequate calories, and it's life-threatening. If your cat has eaten nothing for 24 hours, or less than half her usual intake for 48 hours, call your veterinarian rather than trying another flavour.

Gradual pickiness is different from a sudden stop. Gradual decline usually tracks with dental pain, nausea from rising kidney values, or plain smell loss. A sudden refusal often points to something acute — pancreatitis, an obstruction, a urinary problem, or pain. The ASPCA also maintains a toxic-plant and household-toxin database worth checking if the change was abrupt and you've brought anything new into the home.

Does warming wet food help a cat with a poor appetite?

Yes — warming wet food to roughly body temperature, about 38 °C, increases aroma release and reliably improves intake in cats with reduced olfaction. Stir in 1–2 tablespoons of warm water, or warm the dish for 5–8 seconds in the microwave and stir thoroughly to eliminate hot spots before serving.

Pet owners tell us this single change works more often than switching brands. A few other levers worth trying: sprinkle 2–3 g of crushed freeze-dried chicken or minnow as a "flavour dust" from our cat treats selection; offer a bone broth topper to raise moisture without adding volume; and feed the largest meal at the time of day your cat is naturally brightest, which for most geriatric cats is early morning. During a GTA February, when forced-air heating drops indoor humidity into the 20% range, that extra moisture does double duty for hydration.

How do you feed a hyperthyroid cat?

Hyperthyroid cats have a dramatically elevated metabolic rate and often need 25–50% more calories than a healthy cat of the same weight — but the disease itself must be treated by a veterinarian, not managed with food alone. Feeding amounts should be adjusted only alongside diagnosis, total T4 testing and treatment, because appetite drops sharply once the condition is controlled.

Hyperthyroidism is one of the most common endocrine disorders in older cats, and its classic presentation is exactly what confuses owners: a ravenous appetite paired with steady weight loss. Some cats eat two and a half times their normal ration and still drop 500 g a month. Reviews indexed on PubMed describe muscle wasting, tachycardia and elevated liver enzymes as frequent companions, and concurrent chronic kidney disease is common enough that your vet will look for both.

Two feeding rules matter here. First, high-quality animal protein at 45%+ dry matter helps limit muscle loss during the hyperthyroid phase. Second — and this is the part people miss — once methimazole, radioiodine or surgery brings T4 into range, that inflated appetite disappears and the cat can gain weight quickly on the same portions. Re-weigh every two weeks during treatment and cut intake back toward the 60–80 kcal/kg range as directed by your vet. Iodine-restricted therapeutic diets exist, but they're prescription products dispensed through veterinary clinics, and they only work if the cat eats nothing else — no treats, no tuna water, no hunting.

Do hyperthyroid cats need to eat more?

Before treatment, yes — usually 25–50% above normal maintenance, because thyroid hormone excess raises resting energy expenditure. After treatment begins, no. Requirements fall back toward normal within weeks, and continuing the higher ration is a common cause of rapid post-treatment weight gain.

Which soft foods suit a geriatric cat best?

For a cat over 15, the two most useful wet-food profiles are calorie-dense pâté (for cats losing weight) and high-moisture broth or shredded styles (for cats with kidney or urinary concerns needing water intake). Both are legitimate; they solve different problems. Our nutrition experts at the North York store usually ask one question first: is this cat too thin, or is she drinking too little?

Beyond those two, a few formats earn their place in a geriatric cat's rotation. Inaba's Churu-style purées are useful because a 14 g tube delivers concentrated flavour a cat can lick rather than chew. Tiki Cat's shredded and mousse recipes suit cats who've stopped liking pâté. Freeze-dried raw from brands like Stella & Chewy's or Primal, crumbled and rehydrated with warm water, gives you a soft, aromatic meal at high protein — browse our freeze-dried cat food range if chewing is the limiting factor. Caru and The Honest Kitchen bone broths add moisture and palatability without displacing much nutrition.

Should a cat over 15 still eat dry food?

She can, if she's eating it comfortably and drinking well. But dry food averages 8–10% moisture versus 75–82% in canned, and geriatric cats have blunted thirst responses. Most owners of a 15-plus cat do best keeping kibble as a small measured portion and making soft food the calorie base.

If your cat genuinely prefers crunch, small-kibble senior formulas are easier on worn teeth, and you can soak them in warm water for 10 minutes to soften. Compare options in our dry cat food selection, and look for a guaranteed analysis with taurine listed, at least 32% protein, and moderate fiber content of 2–4% for stool quality. Taurine deficiency remains a real risk in poorly formulated or home-prepared diets; the FDA Center for Veterinary Medicine tracks diet-associated cardiac cases.

Practical next steps for feeding a cat past 15

Start with data, not with a new bag of food. Weigh the cat, calculate her daily kcal target at 60–80 kcal/kg, read the kcal/can figure on whatever she's eating now, and see whether she's actually getting what she needs. Nine times out of ten there's a gap.

• Book senior bloodwork — CBC, chemistry, total T4, urinalysis and blood pressure. Twice yearly past 15, as the CVMA and AVMA both advise for geriatric pets.
• Set a feeding schedule of 3–4 meals, each 60–90 kcal, warmed to about 38 °C.
• Add moisture deliberately — 30–60 ml of warm water or broth stirred into each meal.
• Support joints and coat with omega-3 (EPA/DHA) and, where your vet agrees, glucosamine. Browse cat health and wellness for probiotics, prebiotics and omega supplements suited to older cats; our team can point you to the right dose range for a 4 kg cat.
• Raise the bowl and the litter box entry. An 8 cm feeder riser and a low-entry box remove two daily pain points.
• Log intake for a week. Grams eaten, not "she seemed hungry." It's the single most useful thing you can bring to your vet.

Our store at 1111A Finch Ave W, Unit 2, North York, ON M3J 2P7 is open 7 AM to 11 PM daily, with local delivery available via DoorDash and other apps. Bring the label of your cat's current food and we'll help you compare its calorie density against her target.

For more on ageing-cat care, see our guides to cat wellness needs and pet food for specific needs, or read through the cat blog for texture and litter-box topics that overlap with geriatric care.