The idea behind the hCG diet is that the hormone allows your body to access your fat stores more quickly than it normally could; so, instead of losing bone and muscle mass (as would normally happen on a low-calorie diet), you start losing body fat right away. During pregnancy, this function of hCG provides nutrients and energy for you and your baby; for dieting purposes, since your body is metabolizing that fat for you alone, your energy levels don’t drop from your low calorie consumption, and you also don’t feel as hungry as you otherwise would. In a nutshell: on the hCG diet, your low-calorie intake allows you to start shedding weight, while the hCG injections themselves reduce your appetite and make sure you’re burning the right kind of weight—fat rather than muscle.

It’s important to remember, however, that once the hCG diet gets you to your target weight, it’s your responsibility to keep the pounds you’ve lost off; if you don’t change an unhealthy eating habits you might have had prior to your treatment, you’ll begin to gain weight again. Read how to maintain a healthy weight once you’ve dropped the pounds!