It’s very likely that you are getting more calories and sugar when you drink a smoothie than when eating whole fruits or vegetables, said Sarah B. Krieger, a registered and licensed dietitian nutritionist who spoke for the Academy of Nutrition and Dietetics, a professional trade group.

Smoothies have a “health halo,” but the bottom line is quantity, and people are often consuming a 20- or 24-fluid-ounce smoothie. For example, a medium Acai Superfood Smoothie from Jamba Juice packs in 420 calories and 70 grams of sugar (equivalent to 17.5 teaspoons of sugar).

Even if you’re making your smoothie at home, using only fruits and vegetables with no other added ingredients, you can drink it in just a few minutes, compared with the 15 or 20 minutes it would take to eat the same fruits or vegetables whole, Ms. Krieger said. And if you’re drinking smoothies frequently, you may be consuming a lot more fruit than you would otherwise.

2. They Aren’t as Filling as Whole Fruit and Veggies

While smoothies technically contain the fiber present in fruit and veggies, the process of blending breaks down the fiber so that the energy (read sugar) from the smoothie is released into your bloodstream more quickly causing a rapid rise and subsequent drop in blood sugar.  As a result you’re likely to feel hungrier again sooner after drinking the smoothie than you would have had you eaten the same fruits and vegetables whole.

3. They Often Contain Added Sugars

According to the New York Times article, commercially prepared and store-bought smoothies often contain added sugar, honey or other sweeteners.

4. Green Doesn’t Make It Healthy

Many “green” smoothies are marketed as being good for you, but that’s not necessarily the case. According to the Times,  just because there’s a leafy green in the smoothie, doesn’t mean much. Most green smoothies are made with blends of high-calorie, nutrient-poor apple juice or fruit juice concentrates. Few commercial “green” smoothies are made entirely from leafy green veggies.