comparing calorie counts on kibble

I need to switch Bear's senior food because he's shedding like crazy and I think the current one is too heavy. But I'm confused by the calorie counts. One brand says 350 kcal/cup and another says 300 kcal/cup but the cup sizes look different on the bag. How do I compare these accurately without just guessing?

dont trust the cup. cups are a joke. i use a scale. my ziggy gets exactly 60g per meal. if ur not weighing it, ur just shooting in the dark. check this thread for how to do it right.

The issue is density. 300 kcal in a 1 cup portion implies a much lighter kibble than 350 kcal in the same volume. To compare, you need to convert to kcal per 100g. If Brand A is 350 kcal/cup and the cup weighs 40g, that is 875 kcal/100g. If Brand B is 300 kcal/cup and the cup weighs 30g, that is 1000 kcal/100g. Brand B is actually more calorie-dense. You need the weight of the 'cup' specified on the bag or measured yourself.

Also, check the fat content. High fat drives the calories up. See this post about fat % vs calories. My Milo has thyroid issues so his metabolism is a mess, but for a healthy cat like Bear, you just want to find the one that fits his activity level. If he is shedding, it might not be the food, it might be stress or age.

Dan is right to mention the thyroid, but for a 2-year-old Maine Coon, we are looking at growth and maintenance, not disease management. The calorie discrepancy usually comes from the inclusion of novel ingredients or different processing methods. I would recommend checking the guaranteed analysis for protein and fat specifically. A food with higher protein and lower fat will often have fewer calories per volume, which is better for large breeds prone to joint issues. You can find a breakdown of label terms in this thread.

Okay, so I need to weigh the kibble to get the true calorie density. But if I switch brands, do I need to change the portion size immediately or transition slowly? I am worried about him gaining weight if I just swap it out because the 'cup' is misleading.

transition over a week. mix the old and new. but keep the total weight the same. if the new one is lighter, you might need to give more volume to keep him full, but watch the calories. look at this thread for budget options that are dense enough you dont have to feed huge piles.