Diet supplement are available in just about any form that you can take by mouth – from pills and capsules to powders, liquids, and teas. Some products are taken with a meal, while others are taken instead of a meal. Over-the-counter diet pills supposedly help you lose weight by stimulating your metabolism, your body’s system for utilizing energy. The primary ingredient in products like Dexatrim with Metabolic Support is caffeine, a central nervous stimulant that may help you burn fat through a process called thermogenesis. But the risks of taking these stimulants may outweigh the benefits.