Weight loss shakes, also called liquid meal replacements, are calorie-controlled beverages that replace one or more meals or snacks as part of a weight loss program. Commonly consumed weight loss shakes include SlimFast, Medifast, Atkins and Health Management Resource (HMR).
So, are there any benefits and drawbacks to consuming weight loss shakes? We interviewed several dietitians for their input.
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Pros of Weight Loss Shakes
Weight loss shakes are used in weight loss programs because they are portion-controlled and convenient. "They have a fixed number of calories, usually 160 to 290 calories per shake, and contain key nutrients found in a healthy meal or snack," says Linda Delahanty, M.S., RD, chief dietitian and director of nutrition and behavioral research at the Massachusetts General Hospital Diabetes Center.
"Using weight loss shakes helps simplify the decisions you need to make about what to eat and can reduce [the] time needed to prepare meals," adds Delahanty.
Weight loss shakes also work in the short term. "People who use these portion-controlled foods to replace two meals per day can lose about 50% more weight than those who don't," says Delahanty.
This is because the shakes provide fewer calories than someone typically consumes at a meal. "A caloric deficit, regardless of how it is achieved, can stimulate weight loss...and many individuals find that replacing meals and/or snacks with weight loss shakes allows them to do that," says Cara Harbstreet, M.S., RD, LD, of Street Smart Nutrition.
A 2018 study in Nutrients found that weight loss shakes might lead to more weight loss than a meal with the same number of calories. When overweight individuals replaced all their meals with weight loss shakes for three weeks, they lost more than twice the amount of weight as overweight men and women who consumed the same number of calories but through food. Those who drank the shakes also had reduced food cravings. Weight loss shakes can also help individuals with Type 2 diabetes lose weight.
Jenn LaVardera, M.S., RD, owner of Hamptons RD, says, "Weight loss shakes can be beneficial for short-term weight loss because they help with calorie control while providing all the essential nutrients your body needs."
However, while weight loss shakes can be used to help you lose weight fast, LaVardera says don't expect to maintain the loss. "Once you are off the shakes, you are likely to return to your old eating habits and gain the weight back," says LaVardera.
Do Weight Loss Shakes Work Long Term?
If you consume weight loss shakes for the rest of your life, you might be able to sustain your weight loss long term. The problem is that most people don't—and shouldn't—subsist on weight loss shakes forever. People typically return to eating real food as soon as their weight loss program or diet is over.
"Weight loss shakes do not offer a long-term solution because they are usually not sustainable for more than a few months," says Harbstreet.
This is because the shakes take the fun and pleasure out of eating, says Kara Lydon, RD, LDN, RYT, intuitive eating counselor and owner of Kara Lydon Nutrition. "We often forget that food is meant to be pleasurable; it's what helps us to survive as humans. Imagine if the food wasn't pleasurable. We probably wouldn't be as compelled to eat to survive. Over time, people are going to start seeking pleasure from food again because they aren't going to get it from a weight loss shake."
A 2019 review in Nutrients suggests that weight regain is a problem with most, if not all, diet programs—due to biological and hormonal responses that increase appetite, alter metabolism and promote weight gain. Lydon noted that a 2020 research article inNutrition suggested that dieting is actually a predictor of weight gain.
This may seem daunting, but it doesn't have to be all or nothing. "Using one weight loss shake per day can help keep off the weight you have lost long term or be a tool to help refocus on weight loss if you regain some weight over time," says Delahanty.
Weight loss shakes can be one of many tools in your nutrition toolbox to help you maintain a healthy weight over time. For some people, tracking food intake and weighing regularly may help keep the weight off long term. However, for others, it can ignite an obsession that creates a rigid mindset around weight loss and negatively affects mental health. Professional insight from a registered dietitian is also recommended to help you find a plan that works best for your preferences and lifestyle.
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The Downside of Weight Loss Shakes
Besides not being sustainable long term, there are other downsides to drinking weight loss shakes.
"The severe restriction in calories can create unintended side effects, such as suboptimal intake of certain nutrients, slowed metabolism and loss of connection with hunger or satiety signals," says Harbstreet. "The liquid nature of this diet also can remove fiber from one's diet, potentially altering gut health or creating a less-filling eating, or, in this case, drinking experience."
Fiber helps increase satiety and can help with weight management long term.
Weight loss shakes can also leave people in a dieting mentality—seeing foods as good or bad and feeling guilty over eating "bad" foods. This often leads to a cycle of restricting food, bingeing and then restricting again.
It also doesn't set you up for success in the real world. What do you order if you're eating at a restaurant? What do you eat at a party if you don't have your shake? It makes the transition from weight loss shakes to solid food difficult.
What to Eat Instead of Weight Loss Shakes
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Weight loss shakes lead to temporary weight loss, but they aren't sustainable long term. They leave people in a dieting mentality, take the pleasure out of eating and can be expensive. You can maintain a healthy weight long term by eating real food. Here are three tips on making weight loss work without the shakes.
Focus on Whole Foods
A 2022 study in Nutrients suggests that high-fiber breakfast cereals can be as effective for weight loss as weight loss shakes because fiber increases satiety. Eating breakfast has also been associated with maintaining weight loss long term.
Fiber is also found in whole grains, fruits and vegetables. LaVardera teaches her clients to make half their plate vegetables and eat smaller portions of starches and animal proteins. "Vegetables add fiber and water content to help keep you full and are packed with nutrients. I want my clients to be able to make food decisions in the real world—at the store, at a dinner party, at a work lunch—so they need to know how to choose whole, real foods and not rely on shakes," says LaVardera.
Eat in a Sustainable Manner
Harbstreet agrees that the best way of eating is one that you can keep up for the long term.
"What is most important is identifying sustainable behaviors that allow flexibility and adaptation," says Harbstreet. "Sticking to a rigid or strict diet promotes dieting behaviors and replaces someone's innate sense of trust in their body with an external cue, such as a meal plan, diet or list of approved foods."
Lydon echoes this advice. "Once we let go of the external cues telling us what and how much to eat, we can free up space to tap into the innate wisdom of our own bodies, also known as intuitive eating," says Lydon. "And that is a 'plan' that's sustainable. It's what we were born doing."
What Is Intuitive Eating?
Find a Plan You Can Trust
Still, some people do better with structure. Working with a dietitian can help you find the best long-term eating plan for you and your goals. Many health care professionals recommend an 80/20 approach—80% of the time, aim to make your plate half vegetables, one-quarter whole grains and one-quarter healthy protein; the other 20% of the time, allow yourself to indulge, but do it mindfully. Following this method eliminates the all-or-nothing dieting mentality and the restrict-binge-restrict cycle that many people fall into when trying to eat healthy 100% of the time.
The Bottom Line
Weight loss shakes work in the short term but aren't sustainable in the long run. Focus on adding more fiber to your diet through fruits, vegetables and whole grains. Check out our weight loss meal plans for real food with real benefits.
