by Michael Totten For the dieter, the key to choosing a healthy coffee drink is to know where the calories are hiding. Black coffee alone is calorie-free. As well, many studies are showing that coffee has health benefits. In moderation, coffee can half your risk of getting gallstones or Parkinson's disease, slash diabetes rates by up to 54 percent and even reduce your chance of colon cancer by 25 percent. It can even preempt an asthma ...