Read the suddenness before you read the price tag
Cats refuse food for reasons, and the word sudden in your question is the part to take seriously. A preference that develops over months is taste; a preference that appears in a week can be a symptom. A cat whose mouth hurts may manage only the softest, richest food; a nauseated cat often rejects the food she was eating when it began and accepts a novel food — frequently the expensive one you bought as a rescue. Stale or changed batches play a part too, since cats judge food largely by smell and a familiar food can genuinely smell different from a new bag. So start by watching the whole picture: is she eating the favoured food with full enthusiasm and holding her weight, or is she eating less overall, drooling, pawing at her mouth, chewing on one side, or retreating from meals she used to meet at the door?
When this needs a veterinarian first
Book a check before attempting any retraining if the new pickiness arrives with weight loss, vomiting, loose stool, bad breath, visible tartar or red gums, drooling, or a general flattening of her spirits. Dental pain is a particularly common hidden cause in adult cats and an invisible one — many cats with sore teeth keep eating, but only the food that costs them least effort, which can look exactly like developing expensive taste. A vet can also rule out the internal causes of nausea and appetite change, and it is far kinder to find a sore tooth in week one than after a month of mealtime battles neither of you understood. Bring the details: when it started, what she refuses and accepts, and how much she finishes.
If she is healthy: blend, do not battle
With health cleared, resist the two extremes — caving in forever or staging a standoff. A healthy cat can still make herself genuinely unwell by not eating, and cats should never be left to hunger-strike a point, since even a couple of days of near-no food carries real risk, especially for a heavier cat. Instead, use the food she loves as the vehicle: mix a small proportion of her regular food into the favoured one, serve at set mealtimes, lift what remains after half an hour, and shift the ratio a little every few days toward the regular food. Serve everything fresh and at room temperature so smell is on your side, and try the regular food in a different texture or a warmed form before concluding she hates it — many alleged snobs are texture critics who accept the same recipe as a pâté they refused as chunks.
Check what the expensive food is really telling you
It is worth asking why she prefers it. Pricier foods often carry more animal fat and protein on the surface of each piece, stronger aromas, or a softer texture — all things a cat is wired to value — and sometimes the preference is a fair review of a regular food that is genuinely less palatable or has been sitting open and stale. Store dry food sealed and buy sizes you finish while fresh. Also check the ceremony: if premium food arrives with hand-feeding and delight while regular food is poured without a glance, she may be ordering the experience — give both the same calm treatment during the blend-back.
Keeping the slow blend consistent to the end
A ratio that shifts over two weeks only works if every feeder shifts it together; one person serving the pure premium food out of pity resets the blend to day one, and the cat learns to hold out for the soft touch. Write the current ratio on the food container or in her feeding notes, dated, so the plan survives busy mornings. KinsLe Care Teams makes that blend a shared, visible task, with each feeder logging the meal as given, so the proportion you agreed on Monday is still the proportion being served on Friday — and the cat who seemed to demand luxury quietly returns to eating like a cat whose people out-planned her.