Diet pills work on one of two premises, one being as a fat burner. Ephedra or ma huang, a powerful central nervous system stimulant, is the main active ingredient in fat-burners. Unfortunately, it will not produce lasting weight loss since the "weight loss" is actually water loss. Many of the fat burner diet pills contain stimulants that kick the body into a higher gear. The body is actually running at a faster rate than normal, and so weight is lost.