If you are completely new to lots of fruits and veggies then this may be a form of cleansing, however this shouldn't last more than a day or so. Be sure you are getting enough calories throughout the day. In addition, if using a Blast as a meal replacement, you'll want to be sure to add in some protein (hemp seeds, chia seeds, protein powder, nuts, seeds) and health fats (avocado, nuts, seeds, nut butter) to ensure a complete meal. Also, be sure you are getting enough rest/sleep and keep stress at bay. A light walk or bike ride can help to get your blood flowing too!