A smoothie cleanse is a type of diet that involves replacing meals with smoothies made from fruits, vegetables, and other ingredients like protein powders or nut butters. Smoothie cleanses have become a popular way to try to lose weight quickly by consuming a very low calorie diet for a few days or weeks.
But do these liquid-based diets really help you slim down? And are they safe and sustainable ways to lose weight in the long run?
Here is a comprehensive look at the evidence on whether smoothie cleanses can be effective for weight loss.
What is a Smoothie Cleanse?
A smoothie cleanse is a short-term diet plan that involves replacing solid foods with smoothies. There are many different cleanse protocols, but most involve consuming only fruit and vegetable smoothies for 3-10 days.
Some popular smoothie cleanse programs include:
- The Master Cleanse – Only consume a lemonade drink made with lemon juice, maple syrup, cayenne pepper and water for 10 days.
- The Blueprint Cleanse – Drink six bottles of fresh, organic smoothies per day for 3-5 days.
- The Smoothie Cleanse Diet – Consume only low-calorie smoothies 4-6 times per day for 1-2 weeks.
The premise behind these cleanses is that by consuming a diet of only blended whole fruits and veggies, you give your body a break from digesting solid foods. This may help remove toxins, improve digestion, curb cravings and kickstart weight loss.
Proponents claim that smoothie cleanses offer benefits like:
- Rapid weight loss
- Reduced bloating
- Increased energy
- Improved skin health
- Better digestion
- Detoxification
However, there is limited scientific evidence to support these purported benefits. Let’s examine what the research says about whether smoothie cleanses can help you slim down.
Do Smoothie Cleanses Help You Lose Weight?
There is no doubt that replacing your normal diet with only smoothies will lead to a dramatic reduction in daily calorie intake, which will likely result in short-term weight loss.
However, most of the weight lost on a juice or smoothie cleanse is water weight, not body fat. And as soon as you resume your normal diet, your weight will quickly rebound.
Here is what the research says about the weight loss effects of juice and smoothie cleanses:
- A 2015 study found that people following a 3-day fresh juice cleanse lost an average of 3.5 lbs. However, they regained most of this weight within 15 days after returning to solid foods.
- A small 2014 study showed an average weight loss of 5.4 lbs after a 5-day fresh juice cleanse. But again, most of this was fluid loss.
- A 2019 study found that a 4-week juice fast led to an average weight loss of 18 lbs. But participants regained over half of the lost weight within 12 weeks after ending the juice fast.
While these cleanses can provide temporary, short-term weight loss, they do not appear to be effective long-term weight loss strategies.
That’s because they are very low in protein, fiber and healthy fats, and may only provide 500-800 calories per day. Consuming so few calories is likely below your basal metabolic needs, which can slow down your metabolism.
Extreme calorie restriction also leads to loss of muscle mass. Muscle helps promote metabolism, so losing it can make it harder to maintain weight loss.
In addition, these cleanses eliminate many nutritious foods and are not sustainable for more than a few days. Making drastic changes to your diet for only a short period of time does not promote the development of healthy eating habits.
For these reasons, smoothie cleanses are not an effective or advisable weight loss solution.
Possible Dangers of Smoothie Cleanses
While smoothie cleanses may seem like an easy way to slim down fast, they come with several risks and downsides, including:
Nutrient Deficiencies
When you only drink smoothies for days or weeks at a time, you miss out on important nutrients that come from eating whole foods.
Smoothies often contain a lot of fruits and vegetables, which provide key micronutrients like vitamins, minerals and antioxidants. However, they lack protein, fiber and healthy fats.
Protein helps maintain muscle mass when losing weight. Fiber keeps you feeling full between meals. And dietary fat supports many functions in your body, including vitamin absorption.
Cutting these essential nutrients from your diet can lead to nutritional deficiencies over time. This may cause problems like fatigue, digestive issues, weak immunity, poor blood sugar control and even hair loss.
Blood Sugar Spikes
The fruits and veggies in smoothies still contain sugars and carbs. Without protein and fat to balance out the sugar content, drinking smoothies can spike your blood sugar levels.
Consuming high-sugar beverages on an empty stomach floods your bloodstream with sugar rapidly, causing swings in blood glucose levels.
This can lead to energy crashes, food cravings, headaches and other blood sugar-related issues.
Hunger and Cravings
Smoothie cleanses typically provide very few calories. Consuming so little food leaves many people feeling hungry, fatigued and cranky.
Low calorie intake for several days may also trigger cravings for sweets and other high-calorie foods once you finish cleansing and resume normal eating. This can lead to binge eating or other unhealthy eating patterns.
Loss of Lean Muscle Mass
The body starts breaking down muscle for energy when you consume too few calories for too long. This makes smoothie cleanses counterproductive for long-term weight maintenance.
You want to lose fat when losing weight, while preserving calorie-burning lean muscle mass. Losing muscle can actually slow down your metabolism, making it harder to maintain weight loss.
May Cause Constipation
Smoothies lack the fiber found in whole fruits, veggies, grains and other solid foods. Without adequate fiber, smoothie cleanses can cause constipation in some people.
Going days without bowel movements is not only uncomfortable but can impair the removal of toxins from your body.
Negative Metabolic Effects
Severely restricting calories over long periods can negatively impact your hormone levels, metabolism and overall health.
Studies show that consuming very low calorie diets may:
- Reduce levels of testosterone, thyroid hormone and other hormones
- Slow your metabolic rate as your body tries to conserve energy
- Increase cortisol levels, which can increase belly fat storage
- Lead to loss of lean muscle mass
These shifts in your body may further promote weight regain after the cleanse ends.
May Weaken Immune Function
Your immune system depends on adequate intake of nutrients to function properly. Following a very restrictive diet can weaken immunity, increasing your susceptibility to colds, infections and illness.
One study found that restrictive diets led to a decrease in the activity of immune system cells in obese women over just 8 weeks.
Overall, research shows that juice and smoothie cleanses are NOT effective long-term weight loss strategies and may even be counterproductive. Other diets and lifestyle changes offer safer, more sustainable options for losing weight and keeping it off.
Healthier Ways to Lose Weight
While quick fix cleanses and crash diets may be tempting, they are not the answer for lasting weight loss and better health.
Here are some healthier, sustainable options for losing weight:
Gradual Changes
Aim to lose only 1-2 pounds per week through modest changes to your diet and exercise routine. This leads to an easier adaptation versus extreme changes that shock your system.
High Protein Intake
Eat adequate protein at each meal to increase satiety, preserve muscle mass and rev up your metabolism. Good sources include eggs, meat, fish, dairy and legumes.
More Whole Foods
Focus your diet on minimally processed foods like fruits, veggies, whole grains, nuts, seeds, lean proteins and healthy fats like olive oil. These provide more volume and nutrients.
Portion Control
Be mindful of your portion sizes. Measure snacks and don’t heap plates with mountains of food. Use smaller plates to prevent overeating.
Regular Exercise
Aim for 150 minutes of moderate activity like brisk walking per week. Start strength training 2-3 times a week to build metabolism-boosting muscle.
Mindful Eating
Pay attention to hunger cues. Eat slowly without distractions. Stop when full. Reduce stress-related and emotional eating when possible.
Adequate Sleep
Get 7-9 hours of quality sleep per night. Lack of sufficient sleep can increase hunger hormones and drive overeating.
Hydration
Drink water throughout the day. Proper hydration reduces cravings and helps metabolize fat.
Healthy Smoothie Tips for Weight Loss
While smoothie cleanses have risks, incorporating healthy smoothies into a balanced diet can be beneficial for weight loss and overall health.
Here are some tips for making weight loss smoothies:
- Include protein like Greek yogurt, milk, eggs, protein powder or nut butters.
- Add healthy fats from avocado, coconut, nuts or seeds.
- Use plenty of fiber-rich fruits and vegetables.
- Watch added sugars from honey, agave, maple syrup, etc.
- Add spices like cinnamon, ginger and turmeric for extra metabolism and health benefits.
- Use vegetables like spinach, kale and zucchini to increase nutrients while keeping calories in check.
- Blend in ice to make smoothies thicker and more filling.
- Sweeten with vanilla extract or lemon juice instead of sugar.
Aim for a balance of protein, carbs and fat in smoothies to stabilize blood sugar, curb hunger and give you lasting energy.
The Bottom Line
In summary, smoothie cleanses are short-term diets that involve consuming only blended fruit and vegetable drinks for days or weeks.
While these cleanses may lead to rapid weight loss at first, most of the pounds shed are from water and carbs, not fat. Smoothie cleanses can also promote nutritional deficiencies, blood sugar swings, loss of muscle mass and other issues.
For these reasons, smoothie cleanses are neither effective nor advisable for sustainable weight loss. Making gradual healthy diet changes, controlling portions, exercising and other lifestyle habits provide safer, long-lasting weight loss results.
Incorporating nutritious smoothies into a balanced diet can support weight management. But avoiding extreme cleanses and focusing on overall healthy eating is the best approach.
