The Smoothie Diet (Review): What is it and How Does it Work?

If you heard that the 21 day smoothie diet will make you lose weight easily and quickly but wondered how, my review will explain it and show you how it works.

With any weight loss plan, the emphasis should be on achieving a healthy loss of stored fat through consuming the right kind of nutrition in the right proportions to satisfy your body's needs.

Having examined the 21 Day Smoothie Diet program created by health coach Drew Sgoutas, I'm rather impressed by the way it lives up to its claims.

What is the Program's Main Focus?

21 day smoothie diet reviewThe main focus of this diet plan is to replace two of your daily meals with fruit and vegetable based smoothies. The digital product (e-book) that you can get online sets out how to do this very clearly by making use of the 36 smoothie recipes contained in the book.

You also get instructions on how to make the smoothies and where to buy the ingredients for them along with a three week schedule setting out which recipes to use each day.

How Can Smoothies Help You Lose Weight?

The smoothie recipes, as already mentioned are based around certain fruits and vegetables in certain quantities for each drink. So right away, it is fairly obvious that all refined carbohydrates and added-sugar products are excluded for the two meals the smoothies replace each day.

Knowing that it is refined carbohydrates and sugar that cause weight gain is a head start. The high fructose corn syrup (HFCS) that is present in so many food products on sale in grocery stores is even more so a leading contender for obesity and related health issues. Being aware of this is also very important.

So by excluding all processed foods that you buy in grocery stores and replacing them with freshly made smoothies (created from only whole foods), you eliminate a very large proportion of the food that causes fat storage in the body. When you're not storing fat, you're not gaining unwanted weight.

Although if you exercise along with dieting, you might gain some muscle weight and tone your body, which is desirable!

More importantly, when you're consuming fruit- and vegetable-based smoothies in place of unhealthy processed junk, you're boosting the body's metabolism. You're also aiding digestion by providing much more dietary fiber in addition to the many important nutrients present in the plant-based ingredients.

What Else Can You Eat?

As two of your day's three meals are replaced, that leave one meal you can eat that will contain solid foods. The plan outlines suggestions for these solid food meals that will compliment the smoothies and keep your daily calorie count within bounds for you to reduce your body's stored fat content without sacrificing on taste and enjoyment.

Again, the emphasis for solid food meals will be on using whole foods in place of the more convenient processed food products that it is so tempting to prepare and eat. That's to help keep calorie levels down while also preventing the accidental inclusion of the above mentioned carbs and sugars/sugar substitutes found in processed foods.

What is the 21 Day Smoothie Diet Schedule?

As the name implies, the complete plan lasts for 21 days (three weeks) and consists of three daily meals. One meal (main meal) is solid food and the other two (breakfast and lunch) are smoothies.

The plan also includes a three day detox plan that you can follow if you wish, that replaces all three meals per day with specially prepared smoothies.

There is also the possibility of including a "flex day" in the plan, in which you can consume just one smoothie and two solid food meals.

What Are the Pros and Cons of the 21 Day Smoothie Diet?

As with all eating plans designed to help you lose weight, there are pros and cons with this particular program. Let's take a look at the main ones:


Shopping Lists

To make the diet as easy to follow as possible, the book contains complete shopping lists of the ingredients you will need for each smoothie and which days you will need them for the whole three weeks of the plan.

This really helps you to plan your meals and make for more efficient grocery store visits to buy the items you need when you need them.

No Food Tracking

What is really great about this program is it does not require you to get strict over tracking which foods to eat at every meal or fussing over accurately counting the calories for each item of food you will eat.

You will need some awareness of overall calories consumed each day. The smoothie recipes will take care of that side of things for you, but you will need to be aware of the calories contained in the solid-food meal (again, the recommended recipes will guide you pretty accurately in that).

In any case, there is no need for strict food or calorie tracking each day, which makes for a much easier diet program to follow.

Fruits and Vegetables

All the smoothie recipes are based around whole fruits and vegetables that are naturally low in calories yet high in nutrients and fiber. That means no canned or packaged ingredients!

What's more, you can source your items from organic suppliers for an even greater health boost.


Time Consuming

There's no getting around the fact that preparing and making smoothies takes some time to do it right. Fruits that need peeling must be peeled and some vegetables need to be blanched before blending.

Then there is the additional time factor in clean up, as the blender bowl, cutlery/knives and chopping board all needs to be cleaned after each use.


The smoothies recommended in this diet contain a lot of fresh fruit and berries, which all contain a high proportion of natural fruit sugar as well as healthy nutrients. Some of the smoothie recipes also include honey, which is another sugar.

However, you should also be aware that while natural fruit contains sugar, it also contains high levels of fiber. This helps the body digest the smoothies more completely while releasing the sugars into the blood stream slowly (unlike the high glycemic refined carbohydrates such as grains).

In any case, the high sugar content may cause an issue for people with medical conditions that call for low sugar diets (such as type 1 and type 2 diabetics, for whom this diet is not recommended).

Please be aware that only the whole fruits should be used and not to add any of the fruit juices you can buy at the store. That's because these juices do contain high levels of added sugars and will increase the calories by a lot.

It is better to add water or ice to smoothies to thin or thicken them as required.


By their plant-based nature, many of the smoothies are naturally low in protein and some are also low in healthy fats. It is recommended in the book to ensure consuming at least 50 grams of protein per day by including this in the solid-food meal.

There are some additional ingredients that can be added to smoothies to increase their protein levels, such as chia seeds or spirulina.


Replacing solid meals with liquid alternatives can certainly help people lose weight through calorie reduction. The only problem is that many people do not want to continue this for the long term.

Indeed, the limitation of 21 days is done on purpose to allow people to return to their normal diet after losing weight during the program is they wish.

The unsustainable aspect is that it is quite natural for people to resume their bad diet habits after completing a successful weight loss program and reaching their target weight. This potential problem is addressed in the book which recommends repeating the 21 day diet on a regular basis or as often as is needed.


This is a well written and carefully constructed diet plan that can help a person to lose several pounds in weight over a three week period when the instructions are followed closely and there is no cheating happening.

I personally love making and drinking fruit/veg smoothies more for the health benefits than to regulate my weight which is actually in a pretty good place I'm happy to say. I tried many of the recipes contained in the book and found them to be fun to make and tasty to drink.

For that reason, I feel it would be very helpful to people needing a structured plan to help them lose some weight as long as they're not suffering with any medical conditions such as diabetes that could cause problems.

It may not be as effective as other diet programs such as the ketogenic diet plus intermittent fasting (Keto + IF), but while I personally find that system to be the most healthful and beneficial for dealing with a whole slew of health conditions as well as weight issues, Keto + IF can be quite a big step for most people to take.

Similarly, it may not be as convenient and hands-off as some of the popular meal replacement home delivery diets like Nutrisystem, Jenny Craig or Medifast, for example.

Yet making and drinking a smoothie for breakfast and one for lunch can be a great and even fun way to boost health while losing a few pounds into the bargain, which is why I would recommend this program to my readers (but not diabetics) without hesitation.

Disclaimer: I am an affiliate of the 21 Day Smoothie Diet and earn commission on sales originating from this page.

Lastly, I've included some further Q & A that might help clarify some people's concerns:

What is the Best Smoothie for Weight Loss?

There are a number of very low calorie smoothie ingredients that together can contribute to a powerful means of losing weight.

These include green vegetables such as kale, cabbage, celery, spinach and others such as radish, zucchini and cucumber. These can be mixed with blueberries, raspberries, apple, watermelon, pineapple and even banana for taste.

The total calorie count will remain low yet the mixture will be high in fiber and nutrients for great health and more complete digestion. The fiber will help keep you feeling full for longer and therefore unlikely to crave high calorie snacks as cheats.

What Fruits Cannot be Mixed?

While most whole fruits are great in many smoothie recipes, there are a few that should be avoided for those needing a very low calorie drink.

These include cherimoya (custard apple), grapes, kiwi, mango, papaya for example, although even these can be added in small amounts for taste.

The main fruit-based ingredients to avoid at all costs are store-bought fruit juices. That's because these are high in added sugar and will raise the empty calorie count of a smoothie quite dramatically.

If you need to add liquid to thin a smoothie, always add water. To thicken, add crushed ice!

Is it OK to Have a Fruit Smoothie Before Bed?

I would not recommend having any kind of smoothie before going to bed at night. The main reason being that the absolute best way to maximize your night time sleep for your body's self healing and fat burning processes is to not consume any food or sweetened drinks for a few hours before bedtime.

The reason is pretty simple. During sleep, the body engages in the repair of damaged tissue and all self-healing processes as well as increasing fat burning. However, it will only do that if it is not engaged in the process of digestion, which shuts off the healing and repair process.

If you eat soon before going to bed, your body will be kept busy digesting the food for most if not all of the night. So it won't be doing any healing or repair work or fat burning, which is what you want it to do!

It's really that simple. Digestion or healing/fat burning. One or the other!

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Written by: Dr Harold Long