Not all “cups” are created equal. When experts say up to 6 cups a day is OK for your health, that means six 8-ounce cups for a total of 48 ounces. Additionally, that amount isn’t safe for everyone; pregnant women or people who are attempting to control their blood pressure or blood sugar should stick to a lower amount or avoid coffee entirely. Java is also its healthiest when served black -- adding sugar or cream can increase the calorie count significantly, leading to weight gain and diseases such as Type 2 diabetes.