Remember that ’90s image of a woman in leg warmers drinking frothy pink shakes for breakfast and lunch? While certain products or diet plans may seem dated to us now, the meal replacement industry is still going strong. Many diets on the market today involve swapping out typical meals for shakes, bars, or other prepared foods. Herbalife, Shakeology, Nutrisystem, and Medifast are just a few of the big names attracting consumers with the promise of weight loss on their line of products. If you’ve looked at starting a diet that involves meal replacement, be advised that these programs come with pros and cons — in terms of both potential weight loss and their effect on your lifestyle. Let’s take a deeper look at what you can expect when you swap typical meals for a prepackaged variety.

a Few Pros

A woman drinks a bottled smoothie on a sunny day

1. They do promote weight loss. Meal replacements wouldn’t have stuck around as long as they have if they didn’t actually achieve weight loss results. Like any other method of intake reduction, consuming calorie-controlled bars or shakes instead of full meals does help you shed pounds, often very quickly.

2. They’re convenient. A salad is healthy, but you can’t very easily pack it in your purse, much less leave it there for hours at a time. Meal replacements like bars and shake mixes, on the other hand, are a convenient on-the-go option that can accompany you almost anywhere. And whereas more complex diets require you to get comfortable in the kitchen, these substitutes eliminate the need to plan and prep meals, saving you valuable time in the course of a busy week.

3. They lighten your mental load. “Meal replacements offer something of a sabbatical from food choices,” explains dietitian Julia Stevens, MPH, RDN, CPT, who uses them with clients in a hospital-based program. Stevens notes that people trying to lose weight often feel overwhelmed by choice as they face an average of 200 daily decisions about food. “When we can streamline those choices and make healthy eating easier and simpler, we are able to facilitate a greater weight loss in a shorter amount of time. Then we use that time to relearn healthy habits and how to make healthy food choices.”

4. They may help control blood sugar. You may not associate drinking shakes with improving your blood sugar numbers, but that’s exactly what researchers found in a study of a medically supervised meal replacement program called Optifast. Type 2 diabetics who replaced meals with Optifast products had better fasting blood sugar levels than those treated with traditional diet and lifestyle interventions. While it’s possible this was simply a byproduct of the rapid weight loss these patients experienced, it’s an intriguing testimonial for meal replacement usage in people with blood sugar issues.

And Some Cons

A woman eats a healthy lunch

While meal replacements offer benefits, they also come with some significant drawbacks.

1. They can get repetitive. Many meal replacement programs allow dieters to eat a “normal” dinner after consuming meal replacements for breakfast and lunch. You may get plenty of variety at your evening meal, but limiting two-thirds of your meals to a handful of preset options can get old fast. It may be helpful to make a mental assessment — are you ready to limit yourself to the same cycle of foods day after day?

2. They might leave you unsatisfied. The drastically reduced amount of calories offered by meal replacements means that, unfortunately, they may just leave you really hungry. “I find they are extremely low-calorie and rarely provide an adequate amount of energy,” admits dietitian Kathleen Meehan, MS, RD, LDN. Feeling ravenous not only is unpleasant and can lead to bingeing but also often results in other effects like fatigue, headache, and brain fog.

3. They’re unsociable. Before embarking on any diet, it’s important to consider the factor of its feasibility in social situations. When your boss wants to conduct a one-on-one over lunch or your BFFs are going out for Sunday brunch, are you really going to sit there eating your meal from a plastic wrapper? Commitment to a meal-replacement-based diet can easily be thrown off by life’s circumstances.

4. They may not keep weight off. While losing weight fast sounds like every dieter’s dream, doing so with meal replacements may be just a short-term fix. “Meal replacements aren’t sustainable,” affirms Maria Zamarripa, MS, RD. “As a dietitian, I’ve seen it multiple times in my clients: They lose some weight using meal replacements but gain most of the weight back once they stop using them.”

5. They don’t get to the root of the issue: Unless used concurrently with nutrition education, meal replacements won’t actually teach you how to eat healthy long-term. So when you eventually go off of them, you may find yourself back to square one with less-than-optimal eating habits. For lasting positive lifestyle change, says Meehan, “I’d much rather help people find a pattern of eating that’s sustainable, considers their food preferences, and contains food they enjoy while providing adequate energy to support all the things they want to do.”

Do you have experience with a meal replacement diet? Tweet us at @BritandCo.

(Photos via Getty)