The Smoothie Diet Plan Review
What Experts Say
“The smoothie diet promises rapid weight loss, but pounds shed may be regained when transitioning back to normal eating habits. While increasing fruit and vegetable intake is smart, some people may struggle to meet protein requirements on this diet without proper planning.”
—Chrissy Carroll, RD, MPH
Sgoutas is a health coach (not a registered dietitian) who created the 21-Day Smoothie Diet to help clients lose weight. His e-book, “The Smoothie Diet,” contains 36 smoothie recipes, shopping lists, and a three-week schedule explaining which smoothies to prepare each day. He also offers a “detox” plan with recipes and instructions for replacing three meals a day with smoothies for three days.3
How It Works
On this eating plan, you will prepare and drink two smoothies a day as meal replacements. Your third meal is up to you, but for the best results it should be lower in calories. Sgoutas also suggests one “cheat day” per week but includes a recommended food list for this day. He also says that it is fine to repeat the 21-day cycle anytime you would like to lose weight.
What You Should Know About Cheat Meals
What to Eat
The smoothie ingredients vary, but they focus on fruits and vegetables, with some protein and healthy fats. There is some guidance in e-book for the one solid-food meal you will consume each day (recommendations for what to eat, and some “whole food” recipes). Sgoutas points out that if this meal is too high in calories, the diet won’t work for weight loss. The e-book also includes some suggested low-sugar, high-fiber snacks.
On the “detox” plan, all three daily meals are replaced with smoothies. On the 21-day plan, you’ll consume two meal-replacement smoothies (breakfast and lunch), one solid-food meal, and a few snacks.
If necessary, plan a “flex day,” in which you consume one smoothie and two regular meals. Also of note: The e-book suggests that this diet is not for people with food allergies.
Pros and Cons
Emphasis on fruits and vegetables
Less calorie-counting and food tracking
Shopping lists included
High in sugar
Preparation could be time-consuming
Lacks scientific support
Fruits and Vegetables
The smoothie diet’s recipes contain plenty of fruits and veggies, which are an essential part of a healthy diet. They tend to be low in calories and rich in phytonutrients.
Unlike many other eating plans, the smoothie diet doesn’t require carbohydrate counting, a food diary, or full-time calorie counting. It does recommend being aware of the calorie count in the daily solid-food meal. With recipes and weekly meal plans (that is, smoothie plans) provided, there is not a lot of decision-making or tracking involved, which is a boon for some users.
The e-book contains shopping lists broken down by smoothie and by week, which simplifies grocery-store visits during the three weeks of the diet. But, even with these benefits, experts have concerns about the smoothie diet’s effectiveness and sustainability.
Most of the diet’s smoothies are low in protein, and a few fall short in healthy fats. Sgoutas does emphasize getting enough protein throughout the day, recommending at least 50 grams daily by eating a little with each meal and snack.
However, some people may need additional guidance on this issue—and without proper planning, could fall short meeting their protein needs.4 If you are using a smoothie as a meal replacement, make sure it contains each essential macronutrient: protein, fat, and carbohydrates.
In general, fruit smoothies tend to contain plenty of calories from carbohydrates and perhaps a small amount of fat. But they also need a good source of lean protein. Protein helps build muscle, which you need to maintain a healthy metabolism. Try adding a tablespoon or two of chia seeds to a smoothie. The seeds will thicken your drink and provide a boost of fiber as well.
How and Why to Add More Protein to Your Diet
High in Sugar
The 21-Day Smoothie Diet’s smoothies contain a lot of fruit. While fruit contributes healthy nutrients, it also contains a lot of naturally-occurring sugar. Some smoothies also call for honey, an added sugar.
This could be an issue for people with certain medical conditions (which is why it’s not recommended for people with diabetes).5 This 175-calorie peanut butter smoothie is creamy and sweet without the addition of any extra sugars.
Some smoothie recipes (on the diet and not) are very thick. It can be tempting to thin them out with fruit juice. But juice can add lots of calories and unnecessary sugar. Water will make your smoothie easier to drink and ice will add thickness. Try decreasing the amount of juice and adding water or ice to get the right thickness and flavor for you.
Making two or three smoothies a day (and cleaning the blender afterward) takes time. And while you can easily prep a morning smoothie and take it with you for breakfast on the go, it’s much harder to have a smoothie for lunch if you’re away from home and don’t have access to all your ingredients and a blender.
It is likely that users will lose weight quickly when they start this diet because they are cutting calories (while potentially cutting nutrients like protein and healthy fats). But replacing meals with liquids, and living on so few calories, isn’t something that most people can continue doing for a long time.3
In addition, it is possible to lose muscle mass if you lose weight too quickly. If someone goes back to their regular eating habits and increases their calorie intake, they may find the pounds creeping back. This could be why the e-book suggests repeating the 21-day diet as often as necessary.
How to Burn Fat Without Losing Muscle
There is no strong scientific evidence to support the notion of detox diets—in part because there is no clear definition of what a detox does. The body naturally “detoxes” itself through digestion and excretion (such as bowel movements and sweat). Organs, like the kidneys, are meant to naturally detox the body. No one food or food combination can do this by itself.
Pros and Cons of a Detox Diet
How It Compares
Smoothie diets like this one are popular, but you’ll also find similarities between the 21-Day Smoothie Diet and other short-term, low-calorie, and meal-replacement diets. Be aware though that, often, these don’t meet expert advice on healthy eating plans.3
USDA nutrition guidelines suggest filling your plate with a balanced mix of protein, fruit, vegetables, grains, and dairy. That’s for each meal, not just one per day. It’s difficult to get all those nutrients and food groups into a meal-replacement smoothie and still have it be tasty and low in calories.
For weight loss, the USDA recommends a daily calorie intake6 of about 1500 calories. Sgoutas does recommend approximately 1500 calories per day in the e-book. But the smoothies in “The Smoothie Diet” clock in at much less than that making it difficult to reach the 1500-calorie target without overindulging in the one daily meal.
Creating a calorie deficit is often the best way to lose weight successfully and sustainably. But the right number of calories is different for everyone, because of factors such as age, sex, weight, and activity level. Use this calculator to determine the calorie goal that might work for you.