The simple answer here is that it boosts your metabolism . It accelerates how you burn up the calories you consume. So if you go on a diet, you limit your calorie intake. When you work out, you increase your calorie use. That means it’s much more likely that you’ll have fewer calories for your energy needs. To compensate, your body will then burn up your fat cells for energy. That’s the biological purpose of fat cells in the first place. They’re reserve power. Clenbuterol simply makes it more likely that you’ll need that power so you burn the fat cells and become slimmer.