For cats, the corn, grain, and otherwise carb-filled cat foods that dominate store shelves and are cheaply available are absolutely terrible. Cats are obligate carnivores and aren't built to deal with that kind of food composition at all. Some cats deal with it better than others, but generally feeding your cat these cheap foods will result in it becoming very obese and highly prone to several types of disease.

I don't go as far as some pet owners, buying frozen pet food from Whole Foods and the like, but I do buy my cat high quality meat-based grain-free dry cat food. It's a little pricey but a 9lb cat eating proper amounts of protein doesn't eat much and a large bag lasts a long time. Just make sure to get a good airtight container to keep the food in.

I take care of people's dogs for extra income. There are two primary reasons that my clients' dogs are overweight. The first group don't monitor their dog's weight or how much it eats. "Just keep some food in the bowl so he doesn't get hungry." The second group derive pleasure from feeding their dog, provide expensive meals for it and, in their enthusiasm, end up overfeeding.

Nah pet weight is all quantity and table scraps. Limit scraps and measure well and your pet will be the correct weight. So much easier than my diet. Wish someone measured my portions.