My girlfriend Abi has a very cute little Siamese mix kitty named Amira. Amira is a very active cat...active to the point of being a bit on the spastic side. She climbs book cases, chases anything that isn't nailed down, talks continually, climbs on people, demands attention, and grooms herself constantly.
Amira in her favorite spot...on top of a 7' tall bookcase.
She had been grooming herself so much that there is practically no fur on her tail and back legs. Since she is such a spazz kitty, Abi just assumed her cat was on the mentally interesting side and really did not worry too much about. She always got good marks on her vet checks, did not seem to have any infections or disease, and other than the missing fur, was quite healthy.
Recently Abi moved and Amira now has a new vet. The vet took one look at the cat and basically said "She has allergies. Most likely from grains. She grooms herself so much because she itches all the time." Abi immediately switched the organic grain-based food she had been feeding her cat to Wellness brand low carb cat food. The change was immediate. Amira stop the excessive grooming and now she even has fur coming in on her legs, stomach and tail.
It is interesting that 2 very different cats like Amira and my cat Xena can have very different problems caused by the same thing. Xena got fat and Amira got allergies so bad she made herself half-bald...all from ingesting grains. This is also something you see in people. Some, like me, get fat, and others, while they may stay skinny, can get high blood pressure, allergies and heart disease. Neither humans or felines evolved to eat easily digestible carbohydrates and sugars like corn, wheat, barley, oats and rice. Unfortunately these items are the basis for the average human and feline diet. Whether it comes in a big bag from the pet store or in a cereal box from the grocery store, they can cause health problems and they need to be avoided.