Your 14 day rapid fat loss system on how to lose weight in a week uses a principle called ‘interval sequencing’.
This is high intensity interval training performed at lesser frequency but higher intensity. The idea here is to constantly challenge your body to greater intensity of effort.
When you continuously challenge yourself you will develop lean muscle and kick up your metabolism. Both these cause rapid fat loss and consequently weight loss. The lost weight is fat not lean muscle which is what is lost in other weight loss systems.