At 15, my clinic cat Oliver slowed down but his appetite did not. He still wanted his meals. Still begged for treats. Still acted like a kitten at feeding time.
The vet said something that changed how I think about senior feeding.
"Older cats need fewer calories but more protein. The food needs to change, not the amount."
Oliver was 11 pounds at 12 years old. By 15 he was 9.5. Not because we fed him less. Because we fed him better. Higher protein, same volume, fewer carbs. He got full on fewer calories without knowing it.
Senior cats lose muscle mass. It is called sarcopenia. It happens to humans too. The solution is not less food — it is better food. More protein per calorie. That way they maintain muscle while staying lean.
Most senior cat foods get this wrong. They cut protein and add fiber. The cat feels full but gets weaker. I see it all the time. Skinny old cat with a big belly. Muscle gone, fat remains. It is heartbreaking.
Oliver's diet: wet food, high protein, measured to his MER. We did not reduce his portions. We changed the formula. He stayed 9.5 pounds for three years. Good muscle tone. Still jumped on the exam table. Died at 18, peacefully, of unrelated causes.
I still miss that cat. He was the clinic mascot. Patients loved him. He loved treats too much.
If your senior cat is losing weight, do not just feed more. Feed better. Check the protein percentage. Check the calorie density. Use the calculator to make sure the numbers work.
And if your senior cat is gaining weight? Same answer. Better food, not less food. The volume stays. The quality changes.
Not all senior cats are the same. Some need more calories. Some need less. Oliver needed maintenance. Your cat might need something different. Talk to your vet. But ask about protein, not just calories.