What are the roles of protein in a calorie deficit diet?



"Protein's role in a calorie deficit diet is to prevent muscle mass from disappearing like my patience with poorly researched questions. It maintains muscle mass, supports adaptive responses, and regulates hormones like leptin, ghrelin, and IGF-1. EAAs and BCAAs are crucial, and inadequate protein intake will leave you with a muscle mass that's as impressive as a participation trophy."
 
How does the interplay of protein intake and hormonal regulation specifically impact muscle recovery during intense cycling phases? Are there critical amino acids that could redefine recovery strategies, especially when considering the unique demands of endurance versus sprint training? Additionally, how do protein sources influence not just recovery, but also the hormonal responses that dictate energy expenditure and appetite regulation during a calorie deficit?