1. Keyphrases mixed into anchors – These are anchors with your key phrase + words that are not part of the key phrase (e.g. “gluten-free flour from Bob’s Red Mill”)
2. Brand, natural and URL anchors – These have no reference to your key phrase unless the key phrase is part of your brand (e.g. “Bob’s Red Mill”)

The % of each category shifts according to Google’s algorithm, but you can find some good general guidelines for how to vary your anchor text in this article.

Looking back at our ketogenic diet example, we see that there is actually a lot of variation in the anchor text: