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7 Side Effects Drinking Too Many Smoothies, According to Dietitians

Yes, there is such thing as too much of a good thing.
FACT CHECKED BY Aaron Goldfarb

Smoothies can be a great way to power pack nutrients, especially if you are short on time or on-the-go. Plus, they can work as an entire meal, snack, or pick me up. But they can easily go from a health drink to a health disaster depending on their ingredients.

"A smoothie is only as healthy as the ingredients used to make it," says Brenda Braslow, MS, RDN, registered dietitian nutritionist for MyNetDiary. "You can use a lot of veggies and make it a nutritional powerhouse, or you can add a lot of juice and added sugar that results in too many calories."

With that in mind, if your goal is to make or drink a super healthy smoothie, look for whole food ingredients, like fresh vegetables and fruits, nuts, and seeds.

"If you want to lose weight, I would look for a higher proportion of vegetables, the lowest calorie food group," says Braslow. "Including a good amount of protein can make it more filling. Try to aim for 20 grams of protein per smoothie. You can get protein from ingredients like Greek yogurt, milk and plant-based milk, protein powders, nuts, and seeds."

According to Jerlyn Jones, MS, RDN, registered dietitian nutritionist and spokesperson for the Academy of Nutrition and Dietetics, here are a few ingredients to include for a delicious and nutritious smoothie:

  • Vegetables: celery, beets, spinach, kale, carrots. Vegetables add fiber, vitamins, minerals, and phytonutrients like carotenoids.
  • Fruit: mixed berries without added sugar or syrups, blueberries, raspberries, strawberries, goji berries. These are low in sugar, less likely to spike blood glucose compared to other fruits.
  • Nuts, nut butter, seeds: These are a good source of protein and heart-healthy fats. Ground flaxseeds and chia seeds are great options because they contain omega-3 fatty acids and fiber. Hemp seeds are an excellent source of plant-based protein with all nine essential amino acids.
  • Greek yogurt, milk, and non-dairy alternatives: Plain Greek yogurt and silken tofu are nice alternatives to protein powders. Low-fat milk adds calcium, vitamin D, and other nutrients. Choose unsweetened fortified milk alternatives if you prefer non-dairy substitutes.

However, if your smoothie isn't packed with lots of good stuff, it may have a negative effect on your health and weight loss goals if you drink them too frequently. Here are 7 side effects of drinking too many smoothies.

Read on, and for more on healthy eating, don't miss 7 Healthiest Foods to Eat Right Now.

You may experience stomach issues.

blending smoothie

"For some people, having a large number of raw fruits and vegetables all together can overwhelm their gastrointestinal system," says Marysa Cardwell, MS, RDN, registered dietitian nutritionist and consultant for Lose It!. "If you are having any digestive upset after your fruit and veggie-packed smoothie, you may want to lightly steam some of your veggies before blending. Too much fiber all at once can also be hard for some digestive systems. If this is you, you may want to dial back some of the fiber content of your smoothie."

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You may be eating too many calories.

High protein shake strawberry banana mango smoothie

One of the mistakes you could be making with your smoothie is by drinking it in addition to a large breakfast. "Adding smoothies to your meals may result in too many calories and weight gain," says Braslow. "Tune into the calories in a smoothie and make sure it fits within your daily calorie budget."

Rather than doubling down on breakfast foods, Braslow recommends consuming your smoothie by itself: "Alternatively, using a smoothie as a meal replacement may be a nice choice for weight loss."

You may stop eating fruits and vegetables in their original form.

Berry smoothie

"I've counseled patients who don't like eating vegetables but will happily blend vegetables for a smoothie. They rely on smoothies so much that they stop eating fruits and vegetables in their original form," says Jones. "This is a disservice for adults and especially children because everyone needs to be exposed to a variety of foods, including fruits and vegetables."

They may cause kidney issues.

make spinach smoothie with avocado and grapefruit in blender

"Green leaves are great, but they are also full of oxalic acid, which can accumulate into crystals and cause kidney stones," says Cardwell.

The majority of people don't have to be concerned with this, as these compounds are eliminated in the stool or urine; however, in some sensitive individuals, eating high oxalic acid foods can increase the risk of kidney stones and other health problems.

"If you are prone to kidney stones or have kidney disease, you will need to limit the amount of oxalic acid you are eating in your diet. You can do some swaps like using cooked kale instead of raw spinach and blending it with a high calcium liquid (like milk) to bind some of the oxalic acid. Kale has less oxalic acid and cooking it breaks that down some more," adds Cardwell.

You may not feel as satiated.

Woman drinking smoothie

"If smoothies are often used as meal replacements, they may not be as filling as a regular meal," says Jones. "That's because at least part of feeling full and satisfied comes from chewing food thoroughly. Chewing is an important part of the digestive process and helps produce enzymes to break down food."

They may interfere with certain medications.

blending up ingredients for a green smoothie

"The high Vitamin K content in leafy greens such as spinach and kale can reduce the effects of certain anti-clotting medications," says Jones. "Green leafy vegetables are a staple in smoothies and the amount may interfere with these medications. People taking blood-thinners do not need to avoid vitamin K, but should still talk to their medical team about how much they should consume."

You're going overboard on carbs.

juice into smoothie

"You could end up with too many carbs if you use a lot of fruit, juice, and added honey," says Braslow. "This could be a problem for someone with pre-diabetes, diabetes, or someone desiring weight loss. Instead, balance the fruit sugar with veggies and protein ingredients." (Related: 8 Side Effects of Eating Too Many Carbs.)

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