If you’re like me, living an on-the-go lifestyle, you might have already discovered that smoothies are the perfect solution for helping your nutrition fit into your busy routine.
This brings up a question you might be wondering about too…
If a smoothie is such a healthy nutrient bomb, and so quick to make - why not go for a green smoothie only diet?
On paper, this might seem like the easiest way to stay healthy if you’re pushed for time and many people do indeed go down this route - unfortunately without knowing much about the potential downsides of consuming exclusively smoothies.
There are less drastic modes of liquid diets, which are actually recommended by RD's, such as the Smoothie Diet found here.
This one has good results, but without the risks of an exclusively-smoothie regime.
- Smoothie-only diet sounds like a convenient and effective way to lose weight while consuming nutrient rich beverages
- In reality, losing weight actually becomes more difficult: in the long term you'll lose more muscle than fat and your body will go into starvation mode - it will store fat instead of burning it
- There’s a danger of nutritional deficiencies and digestive issues
- You’ll lose an important part of the joy and fun of eating
- One or two smoothies per day is great for losing weight and a much better idea
- Always consult a registered dietitian before making such a change in nutrition
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If you’re considering such a diet change, it’s important you read this article as well as consult a Registered Dietitian, so that you’ll be truly informed about what it could really mean for your health and weight loss efforts.
Here’s a YouTube video that might have inspired many to embark on a smoothie-only diet, but you should definitely read till the end before you do!
Jenell Stewart has embarked on a 30-Day smoothie diet. She consumed one 16oz smoothie every 2 hours from 8am to 6pm, plus 1-2 servings of fruit and a nut bar - that’s it for 30 days.
The video below was shot after 24 days, when she lost over 17lbs:
The Idea Behind an All Smoothie Diet
There a couple of big pull factors for a weight loss plan exclusively based on smoothies:
Firstly, there is the convenience factor. One of the reasons why smoothies are so popular is the ability to pack in a host of key vitamins and nutrients quickly and easily.
If you don’t have a lot of time to spare on the average day it is an attractive idea, to be able to only drink smoothies and not spend precious time preparing, cooking and eating meals.
Secondly, there is the nutrition factor. The very idea that smoothies can be so good for you leads many people to believe that they can get even healthier if they stick purely to them.
Does it work though? Let's take a critical look at this idea.
Does an Only-Smoothie Diet Aid Weight Loss?
The popularity of this idea rose a few years ago following the story of Jessica Simpson’s brutal diet. She has shed 60 pounds after giving birth, so she could fulfil a deal with Weight Watchers:
Her diet started with a 5 day smoothie cleanse which consisted of eating nothing but liquid smoothies.
Then she gradually moved on to small meals, but still with smoothies as the main nutrition source.
Due to it being such a drastic regime, and considering most of us are not obligated to fulfill multi-million dollar contracts with Weight Watchers... then that's not something RD's or physicians would usually recommend.
In moderation, smoothies are an ideal way to drop a few pounds without sacrificing on the nutrition side of things.
You can just swap out a meal in favor of a delicious smoothie and still be assured that you’re getting vital nutrients.
The calorie difference generally means you’ll lose some weight into the bargain, and if that’s not enough - many smoothie recipes are designed to keep you full for a long time, so you can avoid casual snacking.
If you’re substituting all of your meals for smoothies, the picture looks a bit different and losing weight actually becomes a lot more difficult.
Here’s the deal:
The amount of calories in the average vegetable smoothie isn’t high. This can be great if you’re trying to get to a target weight.
If you’re going to consume only smoothies, and for the long term, then you’re more likely to lose muscle rather than fat. This is important as lean muscle can burn more fat so if yours depletes, your effort to lose weight would be less effective.
Fruit and vegetables are mostly made up of water and fiber. This means they bulk out your smoothies while also being light on calories. The average green smoothie is a maximum of 300-400 calories, depending on ingredients of course.
If smoothies are all you’re going to be eating over the whole day, even 3 smoothies mean you’ll be getting less than 1500 daily calories.
Even if weight loss is your aim, this isn’t enough to sustain you day in, day out. Anything below 1500 calories per day for men and 1200 calories per day for women is generally considered to be a low calorie diet.
Truth is, you’ll be hungry - no matter what goodies you pack into your smoothies to try to fill you up. There’s much more chance that your good intentions will go up in smoke when you think of it this way.
The problem with low calorie diets
Even worse, low calorie diets like the smoothie only diet can actually make weight loss more difficult to achieve.
Your body goes into “starvation mode” if it’s deprived of calories in this way. This basically means that it hangs onto fat for as long as possible so that you can continue to function reasonably well on this lesser amount of calories.
This could be useful for survival, however it is not so great if you’re on a weight loss mission. Your metabolism slows down as a result of the calorie deprivation and weight loss gets harder and harder.
Once you go back to a more normal pattern of eating, you’ll put weight on … much more than you bargained for, most probably!
What if you don’t go back to a “normal” eating pattern? Chances are, you’ll experience some of the nutritional deficiencies that are discussed in the next section!
The Risk of Nutritional Deficiencies
Smoothies are a great way to easily pack some extra nutrients into your day but they won’t provide you a full array of nutrition.
This means you’ll have deficiencies in certain nutrients if you exist solely on smoothies.
Iron and calcium can be there to some degree in green smoothies but you’d need a lot of things like kale to get the amounts you need.
The Problem With Low Protein Plans
As an exclusively-smoothie diet is classed as a plant based diet, not getting enough protein can also be a problem. This can lead to physical symptoms such as tiredness, having little energy and a “fuzzy” head. Lack of protein can also slow down your metabolism and have an even bigger effect on your weight loss efforts.
Generally, vegans and vegetarians who follow a plant based diet will get their protein from other sources but obviously this won’t be an option if you’re following a smoothie only diet. You’re therefore more likely to be lacking in it compared to them.
Adding protein powders to your smoothies is a way to get protein into a smoothie only diet but I believe it should come as a protein boost rather than a substitute for eating protein-rich foods.
What is the Five Day Protein Shake Diet
At the other end of the spectrum, replacing all daily meals with protein shakes also has its health risks.
The “5 Day Protein Shake Diet” is an example of such a regime.
The idea is to consume five protein shakes a day for five days, or for another limited period of time, under medical supervision.
The shakes have very low sugar contents and only little carbs and fat, and thus very low on calories - around 600 to 1400 per day.
This diet has been found to be very effective, but unfortunately it can lead to serious side effects such as abnormalities of the heart and cognitive dysfunction caused by nutrient deficiencies.
A slightly more balanced version of this diet calls for two smoothies a day and one meal. This is still a smoothie fast, but at least you get to catch up with some of the required nutrients while eating a regular low-calorie meal.
Other Health Effects
Deficiencies aren’t the only health issues that can crop up on a smoothie only diet:
The fruits and veggies you put in your smoothies might have started out life as solid foods but once they’re blended, they’re essentially liquid. This is where some of the problems of a smoothie only diet start from.
Our bodies simply weren’t designed for our food to be consumed purely in liquid form. Research done on mice has shown this kind of diet to have a negative effect on their digestive system.
The problem here is that you would not secreting bile from your liver as you normally would, which your body needs for digestion.
The end result? You’re at much higher risk of developing gallstones, and the oxalates found in some dark green leafy veggies might build up and cause kidney stones. It won’t happen to everyone, but it's another risk of going on an extreme kind of diet.
Thus, even though consuming one, two or even three smoothies a day can greatly benefit your health, replacing all meals with smoothies is having “too much of a good thing” - which as usual - is not so great.
How Many Smoothies to Have Per Day
Rather than trying to exist solely on a smoothie only diet, you’re much better off replacing just one or two meals per day with smoothies and having the other regular meals - lunch or dinner.
This way, you’ll get a healthier number of calories to avoid “starvation mode” and fill you up, and a better chance at an overall balanced nutrition.
You also don’t have to worry about the potential for being deficient in important nutrients as you can make sure that these are included in your main meal.
A Word of Caution
It’s never advisable to make any big changes to your diet without consulting a professional RD beforehand.
Embarking on a smoothie only diet definitely falls into this category as it’s liquid only and considered to be at the more extreme end of the scale.
As you’ve probably realized by now, I’m not in favor of a smoothie only diet as there are too many potential problems associated with it and it’s not a sustainable weight loss plan.
It’s also contrary to my view of having your nutrition as a source of fun and enjoyment in your life. This can be achieved with more variety in food selection and serving, enjoying different flavors, textures and food styles.
However, I do love swapping out a couple of meals for smoothies, mainly breakfast and sometimes lunch, or drinking an extra smoothie in between.
This helps me to feel full and keeps me going until dinner. Plus, I know I’ve already got all of my key nutrients in before I sit down for my main meal of the day.
Do let me know your thoughts about this in the comments section! Have you ever been tempted to have a go at it, and how do you feel about it now?
Be sure to share this article so that more people can learn about the effects of this type of diet and the best ways to maintain a healthy weight.