Cat Losing Weight — Even With a Good Appetite?
Weight loss in a cat is rarely 'just aging.' It's almost always treatable when caught early.
How to actually measure it
Eyeballing a cat's weight doesn't work — long fur hides loss, and cats lose weight slowly. Use a kitchen scale (cats fit) or step on a bathroom scale holding the cat, then alone, and subtract. Weigh once a month and write it down. A 1-pound loss on a 10-pound cat is 10% of body weight — meaningful.
Eating well and still losing weight — the big three
1) Hyperthyroidism. Older cats, often middle of the night yowling, restless behavior, big appetite, weight loss. Easy blood test. Very treatable. 2) Diabetes. Drinks and pees more, big appetite, weight loss. Easy to diagnose, manageable with insulin. 3) Intestinal cancer or chronic GI disease (IBD vs. small cell lymphoma). Usually with vomiting or diarrhea. Diagnosed by ultrasound, sometimes biopsy.
Eating less and losing weight
Kidney disease, dental disease, advanced cancer, depression/grief, or pain. Cats hide pain extremely well — weight loss without obvious illness in an older cat warrants a careful exam and full senior bloodwork.
What to ask the vet for
Senior wellness panel including: T4 (thyroid), kidney values (BUN, creatinine, SDMA), glucose, urine specific gravity, urine glucose. Ultrasound is often added if bloodwork is unclear. The earlier you investigate, the better the outcomes — kidney and thyroid disease especially are very manageable when caught early.
Common causes
- Hyperthyroidism
- Diabetes
- Kidney disease
- GI cancer / lymphoma
- IBD
- Dental pain
- Depression
When to worry
- Any 10%+ weight loss
- Weight loss + drinking more
- Weight loss + vomiting
- Weight loss + dull coat
- Cat over 7 with weight loss
- Weight loss + behavior change
Quick actions
- Weigh once a month, write it down
- Track water intake and litter clumps
- Schedule senior bloodwork yearly over age 7
- Photograph the cat from above and the side
- Vet visit for any unexplained loss
Products that may help
Hand-picked, vet-informed gear related to this symptom. Educational recommendations — not a substitute for veterinary care.
LeanLife
LeanLife Weight-Management Dry Food
High-protein, calorie-smart formula to support healthy weight and lean muscle in less-active pets.
PortionPro
PortionPro Automatic Feeder
App-scheduled, portion-controlled meals with a voice recorder — great for weight management and picky eaters.
Affiliate disclosure. Some links on this page are affiliate links. If you buy through them we may earn a small commission at no extra cost to you. We only recommend products we believe help pets, and our picks are never paid placements. Products are educational recommendations, not medical advice — always consult your veterinarian.
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