Aspartame: A man-made sweetener with almost no calories used in place of sugar.

A diet program with aspartame and exercise gives better results than without this sweetener. People lose more weight and regain less weight.

Aspartame is a compound of two amino acids -- aspartic acid and phenylalanine. Because it is essentially half phenylalanine, people who have the genetic disease phenylketonuria (PKU) and cannot metabolize phenylalanine normally need to avoid diet drinks and other products containing aspartame (trade name: NutraSweet).