Dietary supplements are often marketed toward those wanting to facilitate weight loss, fat burning, and building muscle. They are available in every vitamin, health food and drugstore nationwide. The ingredients in these supplements vary. They often contain B-vitamins, for their role in energy metabolism, caffeine and/or ‘natural’ stimulating herbs, such as yerba mate extract, chromium, green tea extract, conjugated linoleic acid, kelp and other substances, such as l-carnitine.