When to Drink Them. Starting the day with a smoothie is an easy and nutritious breakfast that can supply your body with energy and help curb your appetite throughout the day. This makes the morning the most important time to drink smoothies for weight loss. If you have a bad habit of snacking on refined sugars and processed foods, be ready to make a smoothie during the times you cheat so as to provide a better option. Smoothies usually contain blended or pureed fruits and/or vegetables.