They take increased doses to decrease fat and increase muscle mass. The side effects are heart and nerve diseases, glucose intolerance, and higher levels of blood fats. Clenbuterol is a drug that affects the central nervous system. It affects growth, muscle, and body fat. The side effects include tremors, anxiety, faster heart rate, nausea, anorexia, insomnia, heart attack, or stroke.
Caffeine affects the central nervous system by increasing mental alertness and reducing fatigue.
If over-used, it can cause irritability, restlessness, diarrhea, insomnia, and anxiety. It is found in coffee, tea, chocolate, and soft drinks. If you want to improve your sports performance, use only ergogenic aids that have been proven safe. They are legal, healthy, and they work. To gain a more competitive edge, nothing works better than proper training, correct technique, and good coaching.