The strict "detox" plan replaces all three daily meals with smoothies for three days. On the 21-day plan, you'll consume two meal-replacement smoothies (breakfast and lunch), one solid-food meal, and a few snacks. Though not a part of Sgoutas’ "official" smoothie diet, some plan for a "flex day" to make the diet more sustainable.
However, Sgoutas points out that if the regular meals are too high in calories, the diet probably won't be effective for weight loss. Also of note: The e-book suggests that this diet is not for people with food allergies.
What to Eat
Lots of fruits and vegetables
Nutritious meal once per day
What Not to Eat
No solid food for two meals a day
The recipes included in the 21-Day Smoothie Diet contain plenty of fruits and veggies, tend to be low in calories, and provide important phytonutrients. While fruit offers healthy nutrients, it also contains naturally occurring sugar, green smoothies diet the natural program for extraordinary health, which may not work for you if you're trying to reduce your sugar intake. Some smoothies also call for honey, which only adds more sugar.
Additionally, most of the diet's smoothies are very low in protein, and a few fall short in healthy fats. Sgoutas does emphasize getting enough protein throughout the day and recommends at least 50 grams daily by eating a little with each meal and snack. However, some people might find it difficult to meet their daily protein needs on this plan, especially those who don't spend a lot of time meal planning.5
If you are using a smoothie as a meal replacement, make sure it contains each essential macronutrient: protein, fat, and carbohydrates. You might consider consulting with a nutritionist or registered dietician for more guidance—though they would likely suggest that you avoid a smoothie-based diet and try other, healthier strategies instead.