As the owner of a popular green smoothie website, you might be surprised that I do not recommend doing a green smoothie diet.
That’s right. Please do not do a green smoothie diet! It’s not healthy!
Now I’m NOT at all saying that green smoothies are bad for you. They are healthy! They are fantastic for weight loss, too.
It is also fine to do a short term (5-10-day), green smoothie cleanse. Just make sure you don’t return to your old habits when you are finished.
I’m specifically talking about trying to live on nothing but green smoothies for longer than 10 days.
Green smoothies were instrumental in my 40 pound weight loss, skyrocketing energy levels, and a 45-point drop in cholesterol (my levels went from “high” by my mid-20s to “normal” at 30).
BUT, green smoothies aren’t all that I do. I am a big proponent of whole foods, also called “real foods”. I don’t just drink green smoothies to lose weight and maintain my health, I combine them with a whole foods diet and lifestyle.
Sure, I could encourage you to do a green smoothie diet by drinking three green smoothies every day in place of meals, but I would be doing you a disservice. Yes, you will lose weight, and you’ll probably lose it fast. You’ll probably feel great, and you’ll love that all your meals take five minutes to prepare.
But after a while, this unbalanced regimen will show its ugly downsides.
Here are three big reasons why I don’t do green smoothie diets:
Reason #1: The Weight Loss and Health Gains Are Temporary
Any extreme diet (and yes, a green smoothie diet is extreme) can only be maintained over the short term. People do these diets to drop a couple dress sizes before a wedding, or because they are desperate to lose weight and feel better about themselves. But what happens when the diet ends?
The weight comes right back. It always comes back! You can’t drink mostly green smoothies for the rest of your life, and it will probably lead to health problems and nutritional deficiencies (I’ll address this more in my next point). Far better is to make a permanent change to your diet, changes that you can maintain for the rest of your life.
Maybe you lose weight just a little bit slower that way, but then that weight loss and any health gains you get stay with you over the long term.
What I hate the most about extreme cleanse diets, or any sort of fad diet, is that these diets don’t teach you how to eat. They provide a quick fix for weight loss, but they are never a permanent solution. Rarely, if ever, are you given a plan for after the diet. These sorts of diets don’t teach you how to eat healthy so that you never end up back where you started.
Reason #2: You’re Making It Harder To Lose Weight
Green smoothies are not always a calorie-dense food, depending now how you make it. Fruits and vegetables are mostly water and fiber, which adds a lot of bulk to your smoothies.
While they are high in nutrition, they are low in calories. A 32 ounce (946 milliliters) green smoothie, on average, has about 325-400 calories. That’s great for one meal, and you can certainly replace up to two of your meals with these green smoothies per day.
But if you drink three green smoothies per day that average between 325-400 calories (32+ ounces) each (assuming you are even making them large enough to be in this calorie range), you are only getting about 1275-1400 calories, which is insufficient calories to maintain adequate nutrient intake and energy levels for most people – even if your goal is to lose weight.
I have been helping people lose weight with green smoothies and whole foods for more than seven years, and I have found that diets that are below 1500 calories per day are problematic for the majority of people for three main reasons:
Less than 1500 calories per day causes hunger, which leads to intense cravings. Healthy resolve dissolves into binge eating (of junk food) when the body gets desperate enough for calories.
Weight loss stalls as the body enters starvation mode. Metabolism slows down and weight loss becomes difficult or stalls. Stopping the diet brings the pounds right back on and then some, especially if your metabolism is slow to bounce back. This is why so many people tend to gain all the weight back and then some after a diet.
Weight loss may result from both loss of body fat and loss of muscle (you never want to lose muscle).
If you decide to do a green smoothie cleanse, then make sure it is not a starvation diet! I’ve seen 700-calorie per day recipes in some of the most famous green smoothie cleanses out there.
I specifically created calorie-sufficient recipes in my 10-day BLEND cleanse so that you can lose weight and get all of the benefits of a cleanse, without starving yourself or disrupting your metabolism.
You can absolutely replace one or even two meal each day with a calorie-sufficient green smoothie, but I do not recommend replacing all of your meals with green smoothies over the long term.
Another major problem with sub-1500 calorie diets is nutritional deficiencies.
Reason #3: Nutritional Deficiencies During Green Smoothie-Only Diets
You’d think that following a green smoothie diet (replacing all meals) would provide tons of nutrients, and you’d be right. And you won’t become deficient in any nutrients over a 5-10-day green smoothie cleanse.
BUT as a long-term solution, green smoothies cannot provide ALL of your nutrients. A green smoothie-only diet can actually lead to nutritional deficiencies over time.
For example, there is no vitamin D or B12 in green smoothies. If all you are drinking are green smoothies (or you are vegan), then you need to supplement. Don’t let anybody tell you that sea vegetables, spriulina, yeast, gut bacteria, or dirty produce provide sufficient vitamin B12. It’s just not true.
Fruits and vegetables also tend to be low in zinc, and most green smoothie recipes will naturally be low in this mineral.
Calcium and iron, while generally adequate in vegetarian and vegan diets, become very difficult to get in recommended amounts when a plant-based diet veers off into the extreme end. To get calcium and iron in your green smoothies, you need to pay attention to how you are crafting your green smoothie recipes.
Spinach is just not going to cut it for calcium and iron when 1 cup only provides 4% RDA for both calcium and iron. (Kale and dandelion are much better options providing up to 10% RDA for calcium and 5% RDA for iron.)
While it is possible to get double the calcium of cows milk in a green smoothie (see this recipe), many green smoothie meal-replacement recipes I’ve seen out on the Internet only have 1 cup of spinach and no other good sources of calcium or iron. While this is perfectly fine for one meal, a diet of smoothies like this will become problematic.
Iodine is also a major problem during a long-term green smoothie-only diet unless you add sea vegetables like dulse or kelp to at least one of your blends each day. There are no appreciable fruit or vegetable sources of iodine outside of select seaweeds.
While you are unlikely to become iodine deficient during a 7 to 10-day green smoothie cleanse, deficiency can present itself if you attempt to replace all meals with green smoothies over the long term.
Finally, protein insufficiency can be an issue, especially when protein powders are avoided on a long term (30+ day) green smoothie diet, or when relying exclusively on fruits, vegetables, nuts, and seeds for protein. While you might have heard that there is no such thing as “protein deficiency” outside of extreme starvation cases, I have come to believe that there is a such thing as protein insufficiency.
Very low protein diets can cause problems, just like very high protein diets can, and when protein is below recommended intake levels, a host of vague symptoms may manifest like fatigue, foggy head, low energy, and failure to thrive. (Many people dangerously attribute these sensations to detox, but this is not the case.)
For some people, these symptoms may also be present when protein intake levels are at or just slightly above the minimum intake guidelines in strict, plant-based diets (it depends on the person and their activity level).
Another issue with very low calorie diets, especially during extended (longer than 30-days) green smoothie diets, is that two essential amino acids lysine and methionine intake can fall below recommended levels. I have personally experienced this during my experiments with fruitarianism when blood markers pointed to inadequate intake despite meeting or exceeding established protein intake recommendations.
Now these nutritional deficiency risks are low when doing a 7 to 10-day green smoothie cleanse, but the longer you keep it up, the more at-risk you become as reserves become depleted unless you know exactly what you are doing and religiously track your nutrient intake. At that point, the amount of work makes the diet even harder to stick to.
Instead Of A Green Smoothie Diet
Instead of attempting a 30+ day green smoothie diet, shift your diet toward green smoothies AND plant-based, whole foods.
It is also important to have a plan for after the cleanse. Don’t just return to your old habits, or the weight will come right back on. Work toward replacing your other meal(s) and snacks with healthy, whole foods. Use a green smoothie cleanse as an opportunity to reset your body, and then make a permanent change that you can follow after the cleanse.