Whey protein is a double-edged sword: it has a very high biological value score, meaning that this source of protein contains the essential amino acids in the right proportion required by humans, but it also causes higher insulin secretion than other quality protein sources like meat and eggs. My other concern with isolated whey protein is that it does not come along with intracellular minerals such as potassium, magnesium, and phosphorus. In that sense, it is not a complete food like eggs, fish, poultry, or meat. Whey protein can have a place in a well-formulated ketogenic diet as long as that diet contains adequate vegetables.
Read more in our deep dive on protein.