Heat destroys essential fatty acids, amino acids, vitamins, and minerals, and enzymes that your dog would normally obtain from eating raw meat. When you’re feeding, processed or cooked foods, in order for your pet to get these necessary, vitamins, minerals, and amino acids, they have to be added back in through supplementation. For most commercial manufactures, this is a synthetic supplement, not a whole-food source.
When kibble is cooked at high heat, multiple times, and for extended times, that cooking damages, amino acids and proteins and leads to the formation of heterocyclic amines. Cooking starches, the same way creates acrylamides both of these byproducts can lead to cancer, inflammation, kidney damage, and neurodegenerative diseases.
Specifically about fat, at the end of the heating process, when there is absolutely nothing left alive (dead food) , rendered fats are sprayed on along with flavoring to make the brown kibble more appealing to a dogs, taste buds.
High temperatures and pressure that are used in this process damage these critical nutrients making them unavailable for the dog to utilize. Remember when we tell people that they can cook their protein, they should gently cook it, so that it’s not well done, but in fact, almost rare. And any fat in the pan should be discarded as rendered fat. The reason we tell them that it’s because the rendered fat is chemically altered and is no longer bio-available to the dog.
Now apply that thought process to kibble which is cooked at high heat four times.