The guide includes scientific references. You could find these within the notes through the text, and click the hyperlinks to browse the peer-reviewed scientific papers. Really hard-boiled eggs, celery topped with peanut butter or almond butter, and sliced veggies make for easy keto snacks with little to no prep time. https://josuewmzmz.wikirecognition.com/1327057/keto_and_butter_secrets