I have a friend who eats plain sugar. Yes, the white, granulated kind. What are the health repercussions?

Sugar. It depends on the amount, what else is eaten and on the lifestyle of the person. In general everyone needs carbohydrates for normal metabolism. The worst kinds of carbohydrate are the sugars and the worst of sugars are the high fructose corn syrups found in so many foods. Eat a healthy diet with a proportion of complex carbohydrates e.g. Fruits, vegetables, whole grains, nuts and berries.