My name is***** and I can help you today. The most important nutrient for cats is protein. They are true carnivores and need mostly protein as their primary calorie source. You should aim for at least 50% protein, but 65% or more is better.
The problem for consumers is figuring out how much protein is actually in the food. The USDA doesn't regulate food labels beyond ingredients and what is called the "Guaranteed Analysis." This is only minimally useful and doesn't actually tell you much. The analysis is more accurate on dry food compared to canned food but still isn't great.
The most common recommendation is to now feed cats primarily canned food. This is because it is much easier to put protein in a can compared to in a dry kibble (it doesn't like to stay in the kibble shape without lots of carbs to hold it together.) Most canned foods are at least 55% protein.
When reading dry food labels, the guaranteed analysis is fairly close, so you should buy a food that is at least 40% protein, but more than 45% is better. Purina is one of the best foods for having high protein in their cat foods.
So, in summary- all cats should be eating about 3.5 ounces of canned food per day (one small can) and supplementing with dry as needed.
Does this help? What questions do you have?