Workout supplements such as caffeine and creatine may be used to enhance exercise performance for high-intensity, strenuous physical activity, such as training to run a marathon or power lifting. However, a healthy diet with adequate amounts of healthy carbohydrates, protein, and water is sufficient to fuel the body for moderate amounts of physical activity, such as an hour of jogging or bicycling. As workout supplements are not reviewed by the FDA for safety or effectiveness, you should consult with a doctor before incorporating them into your exercise routine and discuss if there are any potential contraindications if you have existing medical conditions.