Smoothies are more popular than ever. But are they healthy?

Few health food trends have demonstrated more staying power than smoothies. Though the blended beverage became mainstream in the 1990s when coffee shops started serving smoothies and juice cafes like Smoothie King, Jamba and Tropical Smoothie Cafe began dotting the country, the world smoothie market has only increased in popularity in the decades since. With a host of affordable at-home smoothie blenders available and countless influencers and celebrities recommending their favorite recipes, the industry is now valued at $27.2 billion, according to one report, and it's expected to grow further still.

Among their many known health benefits, "smoothies are a creative way to increase your fruit and vegetable intake," says Kristen Smith, MS, RDN, spokesperson for the Academy of Nutrition and Dietetics and registered dietitian at Piedmont Health.

What are smoothies?

Smoothies are simply a combination of puréed solid ingredients, often made smoother by adding liquids and colder by adding ice. Some of the most popular foods to blend are frozen strawberries, bananas, blueberries, mangoes, pineapple, cherries, raspberries and peaches. Green smoothies are also popular and often consist of apples, avocado, spinach and kale. "Some of the healthiest ingredients to put in a smoothie include a mix of fruits, vegetables and other nutritious components," says Shelley Rael, MS, RDN, a registered dietitian and nutritionist based in Albuquerque New Mexico.

After favorite solid ingredients are chosen, liquids like water, coconut water, fruit juice, milk, almond milk or soy milk are added to help with blending.

In addition to smoothie varieties made from fresh ingredients in cafes and at home, there are a number of premade, store-bought smoothie and meal replacement shake/smoothie brands available. These include Naked, Bolthouse Farms, Danimals, SlimFast, Premier Protein Shake, Ensure Plus and Carnation Breakfast Essentials. Though protein powder and other supplements are often added to freshly made smoothies, supplemental nutrients are commonly included in many of these bottled or canned smoothie brand varieties.

Are smoothies healthy?

Because every brand or homemade smoothie has its own ingredients, its contribution to overall health can vary greatly. "Smoothies can be high in added sugars without much additional nutrition," explains Rael. "However, you can include healthier ingredients to make it a nutrient-packed meal."

Smith agrees, noting that while many smoothies contain important vitamins and minerals, others "can quickly resemble a milkshake if you are not careful." Indeed, one bottle of this Bolthouse Farms smoothie packs 28 grams of added sugars - 56% of the total amount the U.S. Food and Drug Administration recommends consuming daily. "Smoothies are one way to consume nutrient-dense foods while on the go or with a busy lifestyle," says Uma Naidoo, MD, director of nutritional and lifestyle psychiatry at Massachusetts General Hospital and the author of “Calm Your Mind with Food." "But steer clear of smoothies with added sugar, flavored yogurts, fruit juices, or even ice cream in their ingredient list."

She also stresses the importance of eating whole fruits and not blending everything up since the dietary fiber in whole fruit slows down the digestive process by which fruit's fructose and glucose is turned from food into blood sugar. "Many smoothies are often high in fruits, which when pulverized, become very high in a sudden sugar load entering your bloodstream," she explains.

Smoothies can also contain a lot of calories. Making matters worse, some people add sweeteners like sugar, honey, yogurt or agave to homemade smoothies - all of which add to overall calories. Bottled smoothie brands are often worse and usually pack between 270 and 370 calories in as little as 15.2 fluid ounces.

Are smoothies good for weight loss?

If one is mindful of added sugars and limiting calories, however, smoothies can be a healthy snack or even a meal replacement option and can thereby contribute to healthy weight management. "When it comes to weight loss, smoothies can be a helpful tool when consumed as part of a balanced diet," says Rael.

Smoothies can also help satisfy hunger pangs, which can also contribute to weight loss. To keep calories in check and to create a more filling smoothie, Smith recommends packing one's smoothie with vegetables and including a protein source such as protein powder, nut butter or Greek yogurt. "Smoothies can absolutely aid with weight loss when a satiating, calorie-controlled recipe is prepared," she says.

Naidoo says that her favorite approach to making a healthy green smoothie, "starts with a clean protein powder of your choosing, then add in greens (about 2 cups of spinach, kale, arugula, romaine, or other greens you have on hand), healthy fats (a small piece of avocado), and a healthy liquid to help blend."

Is yogurt good for you? It's nutrient-rich and high in protein.

This article originally appeared on USA TODAY: Are smoothies good for weight loss?