weight gain despite measured food

My cat gained two pounds in the last few months even though I’m measuring her food strictly, and I don’t know what I’m missing.

I’ve been using the same scale I use for baking, so I’m pretty sure the grams are correct. Shadow is a 10-year-old black male on a senior formula. He’s still active but not as much as he used to be. I checked the label and the calorie density hasn’t changed, but I’m stuck. Has anyone else seen this where the math just doesn't add up?

did you check if she is eating your other cats food? i have luna and she steals treats from under the couch all the time. also make sure you are not giving extra treats. sometimes the 'strict' measurement misses the hidden calories.

@KathyW I only have Spot, a 6-year-old white boy, and he’s not a thief. Plus I’m the only one who touches the food. I don’t give treats unless it’s a specific dental one, and I count those in the total daily calories. It’s just the main kibble and wet food.

I looked at senior cat metabolism drop and it mentioned that activity levels drop off a cliff, but he’s still jumping on the cat tree daily. Is it possible his BMR is just lower than the label assumes?

Check the brand history. Some companies change the recipe or the kibble shape without changing the name, which can alter the calorie density per cup. I switched brands last year and my Bear gained weight until I recalculated. See comparing calorie counts on kibble for how to check this. If you are using a kitchen scale you should be fine, but double check the bag for a revision date.

It is quite possible that the 'senior' label is not accounting for individual variance. At ten years old, many cats begin to show subtle signs of endocrine shifts. I would look at thyroid signs to look for to rule out any hormonal imbalance that might be affecting how he processes food. It is not just about the input, but the biological processing. Have you had a blood panel recently? If not, that is the next logical step before assuming it is simply 'slower metabolism.'

Thanks @KarenT. I haven't done a blood panel yet, but I will call the vet to get one scheduled. I was hoping to solve this with math, but I suppose biology is messy.

One last thing: I’ve been using a digital kitchen scale, but I just realized I might be taring the bowl incorrectly or letting it drift. I found this thread from a while back, accurate portioning methods, which suggests using a dedicated pet scale or resetting the tare every single time. Could I have been overfeeding by a few grams a day without noticing? That would add up to a pound over a month.