Metabolizable Energy

Okay, so if I understand ME right, that means if I feed food with higher protein content, then kitty can get more nutrients and calories from it?

So would that mean if I feed the better food, kitty may actually be getting the same or more calories than her previous food, which had more carbs in it?

I recently switched to higher protein content food. There are less calories per can, but even though I calculated how much food would be the same amount of calories, Poppy may have gained a little weight. I'm judging this by how easily she jumps onto the bed. (Getting a scale soon.)

"ME" means calories.Well - a measure of calories. Protein and carbs have about the same amount of calories, though the nutrients from the protein are more bioavailable. If two foods have the same protein content, but one has more calories, then that food is higher in fat than the other.

But yes, it's entirely possible that when eating a diet higher in protein that a cat may need less calories - though as she gains muscle vs fat on a higher protein diet, she'll also burn more calories than she was. My vet (female) is a body builder (not for muscle mass, but for vein and muscle structure). In discussing the whole protein vs calories thing, she said that even though she weighs half what her husband does (she's a teeny little thing!), she burns more calories sitting than he does jogging, just because of her lean muscle:fat ratio.

It is also possible that Poppy is beginning to convert fat to muscle mass: muscle weighs more than fat.

Lazlo, last year weighed 12.5 pounds. The vet wanted him to lose a pound. This year, Lazlo still weighs 12.5 pounds. The difference is that this year, that 12.5 pounds is more lean muscle mass vs. fat, and the vet doesn't want him to lose any weight.

Here's an explanation (technical) of ME: http://www.peteducation.com/article.cfm?c=1+2244&aid=2842

ETA: When we switched from canned to raw, my cats were eating about one 5.5 ounce can of food a day (Wellness, EVO, Nature's Variety, Ziwipeak... ). On raw, my cats that ate 5.5 ounces of canned food need completely different amounts of food. Billy - at 13.5 pounds - needs just 3.6 ounces of raw food. Lazlo - at 12.5 pounds - eats 4.5 ounces of raw food daily. So yes, with higher protein and bioavailability, Poppy may need less food.

Just went to the vet today. Here's the interesting weight results:

Poppy has gained a couple ounces, despite being fed the same or slightly less calories of higher protein content food. I know the couple ounces could be something she hasn't urinated, so I'm going to be weighing her as I cut back a little on the food. I think she's about half a pound too high, as exhibited by her clumsy efforts to jump on the bed.

I hope you'll keep us posted. Because there's been question of whether or not all calories are created equal.