Are Smoothies Healthy? Science, Myths, Weight Loss

Smoothies are an easy way to have a quick, healthy snack. But are smoothies really healthy? Can smoothies cause weight gain or add too much sugar to your diet?

I would like to talk about common myths related to smoothies that you hear all over the media and clear up some misconceptions using science based research.

There is evidence that you should eat some plants whole, but others show the same effects no matter if eaten whole or pureed.

Smoothies and juices can cause a higher spike in blood sugar than the consumption of  whole fruit. Then there is the myth about weight gain from drinking smoothies and the destruction of enzymes or other nutrients from blending your fruits and veggies.

On the other side, smoothies are a great way to add veggies, leafy greens, and many different not-so-tasty foods to your diet. Now, let’s see what science says!

Processing Your Greens

The division of human nutrition and epidemiology at Wageningen University (Netherlands) compared the absorption of the mineral “folate” in spinach (between whole spinach, minced, and liquified spinach). Folate is necessary for the absorption of iron, to make red and white blood cells, and during pregnancy.

Some smoothie myths state that processing leafy greens will destroy the nutrients in the plant like fiber and enzymes.

However, the folate concentration in blood was higher in the group with minced spinach and liquified spinach consumption compared to the group who was eating whole leaf spinach. Even after adding fiber there was no higher folate consumption.

As a conclusion, it is safe to say that you can blend your leafy greens.

Smoothies and Weight Gain?

You can lose weight and also gain weight by drinking a smoothie. It depends on what you put into your smoothie and how you drink your smoothie.

You will feel full longer if you eat 3 fruits than if you drink the puree of 3 fruits quickly. Studies show that the more you chew, the faster you feel full (source). Also, if you turn your food into a soup (hot smoothie) you eat less calories throughout the day.

Another study found that eating your meal slower will help you feel fuller and more satisfied after finishing the same meal eaten faster (source), which could be the reason why soups are so filling: they are consumed more slowly due to the heat.

What does that mean for smoothies?

You will not gain weight and you will feel full and satisfied for longer if you consume your smoothie slowly. Enjoy your smoothie as long as it would take to eat each fruit raw.

Are Smoothies Good For Weight Loss?

You will lose weight easily if you eat less calories than you burn during the day. This can be achieved in many ways and on many diets. I always suggest not cutting too many calories. Try to avoid any fad diets as well. The most important parts of successful weight loss includes finding a healthy lifestyle and creating new healthy eating habits that last long term.

Smoothies are a great way to include important nutrients to your diet like omega-3, vitamin K, protein, fiber, and other vitamins and minerals.

Drinking smoothies is an easy way to include your daily dose of leafy greens as well. It can help you maintain energy levels and focus. I usually drink my smoothie as a snack between breakfast and lunch.

If you burn 2000 calories per day and you want to gain weight, add a 300-600 calorie smoothie and this will help with weight gain. If you would like to lose weight, or create a more healthy lifestyle, use smoothies as a healthy snack or breakfast (also to go).

Danger of drinking your calories quickly

Consuming a lot of calories quickly can have negative side effects. First of all you won’t feel satisfied and full even though you consumed a lot of calories. As mentioned above, the time of consumption matters. If you drink your smoothie quickly you might feel hungry faster, which will lead to more calorie consumption during the day, and therefore weight gain.

The other danger of drinking all the nutrients quickly is the blood sugar spike that can occur…

Smoothies and your Blood Sugar

The importance of a healthy diet is to keep your blood sugar levels as even as possible. Extreme sugar spikes and falls can lead to insulin resistance and also an imbalance of your hormones.

Some foods show different blood sugar spikes in different forms. Rice, for example, shows a higher insulin spike blended compared to eating the rice whole, but blended beans do not show a higher spike compared with whole beans (source).

Fruit juice will also spike your blood sugar because all the fiber is removed. The apple itself contains fiber which balances blood sugar levels naturally. But the disrupted fiber in an apple puree also has negative effects:

“Serum-insulin rose to higher levels after juice and purée than after apples. The removal of fibre from food, and also its physical disruption, can result in faster and easier ingestion, decreased satiety, and disturbed glucose homoeostasis which is probably due to inappropriate insulin release. These effects favour overnutrition and, if often repeated, might lead to diabetes mellitus.” (source)

On the other side, drinking a pureed banana does not differ in glucose response compared to eating a whole banana (source). And if you add blueberries to your smoothie, studies show a ‘reduction in glucose concentrations over time’ (source). Similar studies showed improved blood glucose with mango supplementation (source).

Tips on preparing a healthy smoothie

While the wrong ingredients (like apples) can make your smoothie less healthy, ingredients like spinach are better consumed in a smoothie. There are some things to consider when making healthy smoothies.

Your smoothie should not influence blood sugar levels negatively. You don’t want to increase your risk of insulin resistance, hormone disruption, and inconsistent energy levels throughout your day.

Here are my top tips to make smoothies that are filled with antioxidants, help control and improve blood glucose, and are super nutritious:

  • Always add at least 1 cup of spinach
  • Use fruits like banana, blueberries, and mangoes
  • Add 1 tablespoon of ground flaxseed
  • Add about 3-5 nuts
  • Add 1/4 cup beans for fiber and protein
  • Drink your smoothie slowly
  • Always use whole foods, no juices
  • You can use (unsweetened) almond milk or (unsweetened) nut butter as well

Adding spinach to your meals or smoothie will also help you feel full longer: Meals with spinach were compared to meals without spinach and their satiety effect.

“The largest spinach portions augmented satiety and reduced the postprandial glucose response.” (source)

Flaxseed added to your smoothie provides multiple benefits. It adds a thicker consistency which makes the smoothie more filling (source) and a “small dose of flaxseed fiber significantly suppresses appetite and energy intake” (source).

Flaxseed plays a pretty significant role in lowering blood pressure. There is a seven point drop of blood pressure from consuming 1 tablespoon flaxseed a day (source). That means 46% less stroke risk and 29% less heart disease risk. Flaxseed prevents cardiovascular disease in general (source) and lowers LDL levels most when consumed in a drink (source).

In this study they compared nine tree nuts and found that walnuts might be the healthiest: “Walnuts had the highest total phenolic and flavonoid contents (1580.5 ± 58.0 mg/100 g, 744.8 ± 93.3 mg/100 g, respectively). Walnuts also possessed the highest total antioxidant activity (458.1 ± 14.0 μmol of vitamin C equiv/g of nut). Both soluble phenolic and flavonoid contents were positively correlated with total antioxidant activity”.

Another study shows that the consumption of unsaturated fatty acids found in nuts “is associated with improved lipid profiles, a lower potency of intermediate biomarkers of atherosclerosis, and lesser incidence of cardiovascular diseases” while walnuts are especially rich in these unsaturated fatty acids.

Adding walnuts to your smoothie is a great way to get some healthy fats that will also help with the absorption of other nutrients in your smoothie.

Healthy Green Smoothie Recipes

Combining all the scientific evidence AND making a smoothie that tastes good, here is a recipe that I like:

  • 1/2 lemon, peeled
  • 1 banana
  • 0.5-1 cup berries
  • 1 cup almond milk
  • 2 almonds
  • 3 walnut halves
  • 1.5 cup spinach
  • 1/4-1/2 cup beans (using 1/2 cup, you can lightly taste the beans. If you don’t like this only use 1/4 cup)
  • 1 T flaxseed
  • optional: 1 brazil nut (for lowering cholesterol or adding selenium), 3 dashes turmeric with a tiny dash of back pepper (anti-inflammatory)

Quick nutritional overview of this smoothie:

This smoothie contains about 400 calories and 14 g of protein. It is very high in calcium, iron, magnesium, vitamin A and K, fiber, omega 3, and folates.

Remember to drink this slowly!

Check out the Meal Planner with plenty of healthy smoothie recipes or download the free meal plan below: