Maybe you’ve tried drinking smoothies to lose weight. How’d that work out for you? Success depends on a lot of variables, such as the makeup of your normal diet, how much you exercise, and what kinds of smoothies you either make or buy.

For some people, smoothie meal replacements can help them achieve a calorie-deficit while supplying important nutrients that might be lacking in their normal eating. For others, drinking smoothies for weight loss can turn into an unwelcome surprise, backfiring by making them gain weight and, worse, inching them closer to type 2 diabetes.

For those reasons, some dietitians are smoothie fans, while others advise their clients against them or suggest being judicious about how they’re made. Below, we’ve gathered opinions from some of the registered dietitians on our medical advisory board. You be the judge.

Thumbs Up: Protein slows digestion.

Smoothies can be a great way to get in extra protein and nutrients without a lot of effort and might help you lose weight.

“Protein helps slow down digestion, so it gets you full faster and keeps you full longer,” says medical board expert Amy Goodson, RD, CSSD, author of The Sports Nutrition Playbook. “Make a smoothie with 20 to 30 grams of protein with milk, Greek yogurt, and/or protein powder to increase satiety. The liquid volume often gives people a feeling of fullness.”

Thumbs Down: Eat your calories.

“Personally, I am not a fan of smoothies for weight loss. I recommend eating real food and eating calories not drinking them for weight loss,” says medical expert Julie Upton, MS, RD, co-founder of Appetite for Health Consulting. “For some people, smoothies may help them lose weight while for others it won’t. Losing weight means that you have created a calorie deficit. If drinking a smoothie for a meal results in you consuming fewer calories overall, it will help you lose weight. If you drink a high-calorie smoothie that adds calories or maintains your calories your weight may actually increase.”

Thumbs Up: Smoothies should contain the healthy trifecta.

“Smoothies can absolutely be a healthy weight-management staple,” says Lisa Moskovitz, RD, CEO of NY Nutrition Group, author of The The Core 3 Healthy Eating Plan. “If you’re trying to intentionally lose weight, focus on protein, fiber, and fat—the healthy eating trifecta.”

Protein can come from Greek yogurt, milk, tofu, or protein powder. Fresh or frozen fruit offers fiber and adding in a vegetable, such as spinach, kale, zucchini, or cauliflower, provides volume and additional gut-friendly nutrients. Fat like avocado, chia seeds, or almond butter, helps with staying power and satisfaction, she says.

“I often recommend smoothies as an excellent method to get in several food groups,” says Moskovitz. “The trick is to add volume with vegetables. Not only are vegetables high in nutrients and low in calories, but they’re teeming with metabolism-supporting and energizing nutrients.”

Thumbs Down: Be wary of store-bought smoothies.

When you blend a smoothie at home, you have control over the ingredients. Not so at smoothie shops and convenience stores.

“Smoothies purchased at stores often contain added sugars in the form of ‘turbinado,’” says Goodson. “This added sugar can quickly add up to lots of calories. Be sure to evaluate the calories of all the ingredients and smoothie servings sizes if weight loss is your goal.”

Thumbs Up: Go easy on nut butters.

“I typically recommend smoothies as a snack or part of a meal with something chewable such as a slice of toast,” says Laura Burak, MS, RD, owner of Laura Burak Nutrition.

Pairing a smoothie with something chewable makes it more satisfying. If your goal is weight loss, Burak advises keeping an eye on ingredient portions.

“All it takes is adjusting the ingredients and using fruit without added sugars or syrups, low-sugar yogurts and milk, and portioning out the calorically dense ingredients like nuts and nut butter so that you create a balanced meal or snack that fits into a diet for your specific goals,” she says.

Thumbs Up: Good for “Breakfast Skippers.”

Like most dietitians on our medical board, Lauren Manaker, MS, RDN, author of The First Time Mom’s Pregnancy Cookbook and Fueling Male Fertility, believes smoothies can be appropriate for weight loss, depending on the ingredients chosen, the portion size enjoyed, and what’s included in the eating plan for the rest of the day. Smoothies can be particularly useful to “breakfast skippers,” she says.

“We know that 90% of Americans are not eating the recommended servings of produce and people who regularly eat breakfast tend to have fewer nutritional gaps, which may help support weight loss goals,” says Manaker.

Smoothies should always contain healthy carbs, protein, healthy fat, and fiber to promote satiety. And portion sizes should be appropriate.

“Chia seeds and hemp seeds are easy additions to weight loss smoothies that check the healthy fat, fiber, and protein boxes, making them typical go-to ingredients when I am guiding clients about how to create a weight loss-friendly smoothie,” Manaker says.

Thumbs Down: Avoid a blender blunder.

With a smoothie or any blended or juiced drink, it’s easy to unknowingly swallow a lot more calories than you expect, so be mindful, according to Tammy Lakatos Shames, RDN, CDN, CFT, and Lyssie Lakatos, RDN, CDN, CFT, also known as The Nutrition Twins.

“We explain it to our clients this way: when you eat four apples, you’re aware you’ve eaten them, but when you drink four blended apples, it may blend down into a cup or less of liquid, and you may not realize how much you’re consuming,” they say. “Typically, when you drink your calories, instead of eating them, it isn’t as satisfying as when you eat the real food, and you end up eating more calories later in the day. And, if you’re loading your smoothies with sugar, syrup, overdoing the fruit, or other add-ins, you could be unknowingly creating a calorie bomb.”

Thumbs Up: Add fat-burning phytochemicals.

As long as their clients stay mindful of the blender blunders when making smoothies, The Nutrition Twins do believe smoothies can be a great part of a weight loss diet.

“They’re especially helpful for people on the go who often choose unhealthy, calorie-dense foods when they’re in a pinch,” they say.

Tip: Add vegetables to your smoothies to boost satiating fiber and nutrients while keeping overall calories low. They recommend their recipe for Blueberry Chai Protein Smoothie.

“It’s a great weight-loss snack because you get about 18 grams of satisfying protein in less than 200 calories, and it contains helpful ingredients for weight loss,” they say. “The pea protein powder aids in weight loss even when calories aren’t restricted and is actually more effective than whey protein at fighting against hunger. Berries contain the phytochemical C3G, which increases fat metabolism and suppresses appetite. And naturally sweet cinnamon stabilizes blood sugar and reduces body weight and belly fat, helping to prevent obesity.”

Thumbs Up: Add fiber to your smoothies.

Drinking smoothies is an easy way to get a lot of nutrients like fruit, healthy fats from nut butter, protein, and fiber in one glass.

“The protein content and fiber from the fruit and veggies can help individuals experience feelings of fullness in the hours of consuming a smoothie,” says Goodson.

She recommends the following ingredients for a good smoothie for weight loss:

• High-quality protein like cow’s milk, Greek yogurt, or protein powder
• 1-2 servings of fruit. A serving could be 1/2 banana, 1/2 cup chopped fruit, 1 cup berries, etc.
• A handful of greens like spinach or kale for added fiber and nutrients
• 1 Tablespoon of healthy fat like nut butter, chia seeds, or ground flaxseed