Aside from fiber, liquid can also offer that full feeling, as well as prevent the bloating that accompanies constipation. Aside from hydrating fruits and veggies, go for low-cal options like straight-up water, coconut water, green tea, or unsweetened almond milk (it's only 30 calories per cup).
Elyse suggests also trying coconut milk, kombucha, or kefir, and Stephanie and Willow love adding a few ice cubes, since it makes the smoothie frostier. If you're worried about the sugar content but love using coconut water or coconut-water ice cubes, Willow suggests cutting down slightly on the fruit when using it as an ingredient.
This debloating pineapple-papaya smoothie is made with cucumbers, coconut water, and ice cubes.