Because it's best for health and well-being. Check out this video featuring Dr. Jennifer Guadiani, MD a physician who specializes in treating those with eating disorders https://youtu.be/E2isludJPnM. She explains why this model is best for all - not just those with eating disorders.
Start with Christy Harrison's site - https://christyharrison.com/ - she's a registered dietician who has many resources - including a great podcast to help define these terms.