Just hearing the word “smoothie” conjures up images of thin, fit health enthusiasts. You know the ones: They’re in their 40’s but look about 25, have glowing complexions, and carry a yoga mat everywhere they go.

That might be your mental image, but are smoothies really all they’re cracked up to be? Well, it depends upon what you’re actually putting in them. Some of you are probably doing it right, while others are basically drinking sugar-laden calorie bombs.

Are you making them at home or buying them at a local juice bar?  If you are visiting the neighborhood juice bar, you’re likely getting a lot of unwanted sugar and calories from fruit juices, ice cream, or sherbet that they will add for flavor.  Throw your “healthy smoothie” thoughts out the window if this happens.

What kind of fruit are you using? Fresh is best, and frozen fruits are an acceptable substitute in a pinch. If you’re using fruit juices to flavor your smoothies, most of the fruit’s fiber was left at the bottling factory. Anything called “blend”, “cocktail”, or “nectar” likely contains a significant amount of added sugar. Canned fruits are often packed in corn syrup.

Are you including vegetables? This is a great way to include more vitamins without adding a lot of extra sugar. Leafy greens like kale are best, but if you hate the taste, try cucumbers, beets, carrots, or spinach.

Do your smoothies contain dairy? Once you add ice cream, you’re really making more of a milkshake than a smoothie. Plain yogurt or low-fat milk are better, and you can add a tablespoon of cacao powder for a chocolate flavor.

What else are you adding? Nuts and nut butters can be used sparingly; they’re a great source of protein, but they’re also pretty high in calories, and some are loaded with sugar. Pumpkin or chia seeds are another good way to round out your drink. Avoid the temptation to flavor your smoothie with honey or syrup; try cinnamon, ginger, or cayenne instead. Train your taste buds to crave flavors other than sweets!

How big are your smoothies? A 12-ounce serving is plenty.

If you’re concerned about whether you’re getting enough vitamins in your diet, don’t rely on your blender to do the job. Talk to your physician about nutrition, and he or she can refer you to a dietitian if necessary.