Clenbuterol increases your body temperature through a process called thermogenesis. Once your body temp is up, your metabolism is then primed to burn off more calories. Since fat is stored in the body as energy, your body can use the calories that you already have stored. This can decrease your body fat and lower your overall weight. Because clenbuterol is a bronchodilator, it opens up your airways when you take it. This is helpful for those with asthma. For athletes, this allows them to increase their stamina by having more airflow moving around the body. More oxygen is available, so you can perform harder and better.