The reason for having these definitions is as follows: Because alcohol is beneficial to the heart, people who drink at the USDA moderate drinking limits are healthier than both abstainers and no-risk drinkers. Abstainers and no-risk drinkers are equally unhealthy. People who exceed the no-risk drinking guidelines are more at risk for health related consequences than people who do not drink at all.
Therefore, HAMS uses the terms "moderate drinking" and "no-risk drinking" (or "risk-free drinking") as follows:
HAMS refers to people who have made improvements in their drinking patterns but who are drinking above the risk-free limits as practicing a Harm Reduction Program, or doing HR for short.
REFERENCES:
CDC. Alcohol and Public Health - FAQs
NIAAA. (2005). Helping Patients Who Drink Too Much. A CLINICIAN'S GUIDE. Updated 2005 Edition.
NIAAA. Alcohol: what you don't know can harm you.
USDA. (1997). DOES ALCOHOL HAVE A PLACE IN A HEALTHY DIET?