Weight that drifts down on its own is a symptom, not a phase of ageing
Old age itself does not quietly melt a healthy cat away. When an older cat loses weight without eating less on purpose, something has changed in how she eats, digests, absorbs, or uses food, or in how much energy her body is burning at rest. The loss is often slow enough to miss week by week: the spine feels a little sharper, the hips a little more prominent, the face a little narrower, while the cat still trots to her bowl and seems herself. That gap between looking bright and steadily shrinking is exactly why the scales matter more than impressions.
Why a cat can eat normally and still get thinner
Appetite is a poor measuring stick in senior cats. A cat with sore teeth may still arrive for meals but chew less, drop pieces, and quietly take in fewer calories than she needs. Another cat may eat every bite offered yet absorb less of it if her digestion has changed, or burn through food faster because an overactive internal system is running her metabolism too hot. Kidney changes can cost the body protein and fluid in ways that trim condition over time, and muscle loss itself accelerates the slide. Several of these threads can run at once, and none of them can be identified from the kitchen doorway, which is why a hands-on examination and appropriate screening tell you more than another month of watching.
Confirm the loss properly before you worry or dismiss it
Start by making the number real. Weigh your cat in her carrier on the same scales, subtract the carrier, and write the result down with the circumstances, then repeat in the same way rather than mixing methods. Run your hands along her ribs, spine, and hips and note what you feel compared with a month ago, and pay attention to the supporting evidence: is she asking for food more often, drinking more, using the tray differently, vomiting, or leaving food she once finished? This small record turns a vague worry into a trend a vet can act on.
What the vet visit adds that home watching cannot
At the appointment, expect the vet to weigh her accurately, feel for muscle condition as well as fat, examine her mouth for painful teeth, listen and palpate carefully, and discuss screening suited to her age and findings. That combination separates the cat who simply needs a feeding adjustment from the cat whose weight is flagging something internal that early support can genuinely help. Going early matters because most causes of senior weight loss are easier to manage before dehydration, weakness, and lost muscle stack on top of the original problem. Bring your home weights, notes on appetite and drinking, and a list of everything she eats, including treats and food stolen from other pets.
Feeding responses that help while you arrange the visit
Do not crash-diet in reverse by flooding a thin senior cat with rich extras before she has been seen, and never let an older cat who has stopped eating simply miss meals while you wait. Offer her usual food in smaller, more frequent servings, warm it slightly to release its smell, and make sure she can reach it without competing with younger cats or climbing to a high feeding spot. If she shares a home with other pets, feed her separately for a while so you know exactly what she actually ate. Any diet change for an older cat with unexplained loss should follow the vet's findings, not precede them.
A running record in her KinsLe Pet Passport, with home weights beside examination findings and feeding plans, lets you and your vet judge whether your older cat is truly holding steady or still slipping between visits.