Almost half of Americans are trying to lose weight at any given time, and many of those people who are desperate to shed some pounds quickly will opt for some type of protein shake diet. While following one of the many shake diet programs out there for a short period of time, like five days or a week, probably isn't going to cause any harm, your results likely won't last.
If you want to lose weight, you're better off making lifestyle changes that you can sustain over the long-term, instead of looking for a quick fix. If you do decide to swap your meals for protein shakes, talk to your doctor or a qualified nutritionist to get the OK before you start.
Protein and Weight Loss
When it comes to weight, protein is often considered the most important macronutrient for keeping you on track. Of course, the other macronutrients (carbohydrates and fat) also play a role, but it's protein that's often credited with keeping you full so you can stick to your plan and see results.
According to a report published in the American Journal of Clinical Nutrition in April 2015, higher protein diets may help increase the number of calories you burn by boosting metabolism both when you're resting and right after you eat.
Protein can also prevent your body from decreasing the number of calories you burn at rest (a physiological response known as adaptive thermogenesis) and from plateauing as you lose weight. It can also help you feel full faster and for longer.
But even though protein plays a role in weight loss, does that mean you should go on a strictly protein shake diet plan? Probably not. Not only are protein shakes lacking in other essential vitamins and minerals, but the results are often short-lived.
If you're on a protein shake diet for a week or five days, it's probably not long enough to cause any real harm, but there's a good chance you'll regain any weight you've lost when you start eating whole foods again.
Protein shake diet programs are built around the idea of calorie restriction. It's pretty well-documented in the scientific literature that following a calorie-restricted diet, especially when that diet involves the use of liquid meal replacements, eventually ends up in weight regain, sometimes even more than you lost.
According to an August 2013 statement in Diabetes Spectrum, the journal of the American Diabetes Association, replacing one or two meals a day with meal replacement options like shakes or bars can lead to a significant amount of weight loss, but in order to maintain the weight loss, you have to stick to the plan indefinitely. As soon as you reintroduce solid foods, you'll likely gain the weight back.
Another study published in Perspectives on Psychological Science in September 2017 explains that this might have to do with hormonal changes that occur as a result of restricting calories. When you're not eating enough, it negatively affects a variety of different hormones, including leptin, ghrelin and insulin. Instead of signaling that you're full and have had enough to eat, these hormones work against you, making you feel hungrier and storing the calories you do eat as fat.
Protein or Meal Replacement Shakes?
If you do decide to follow a shake diet plan for a week, choose wisely. As the name implies, protein shakes are high in protein, but usually not much else. They're typically designed to help you meet increased protein needs during periods of intense exercise when it can be hard to get enough protein through meals alone.
On the other hand, meal replacement shakes are designed to mimic a complete, low-calorie meal. In addition to protein, they also contain carbohydrates, fat, vitamins and minerals in balanced proportions to help you meet your daily needs of both macronutrients and micronutrients.
Relying on protein shakes alone can set you up for nutrient deficiencies, whereas meal replacement shakes usually contain everything you need, at least for the short term.
But, not all pre-packaged meal replacement shakes are the same. Some are high in sugar, while others are high in artificial sweeteners — neither of which are desirable. Drinking these shakes may help you lose weight in the short-term, but the benefits end there.
If you opt for a pre-packaged meal replacement, make sure to check ingredient lists and choose ones with the least amount of additives and sugar.
Drawbacks of Meal Replacement Shakes
Although meal replacement shakes are designed to mimic a meal by providing nutrients, vitamins and minerals that protein shakes may not have, there are other drawbacks. The vitamins and minerals in meal replacement shakes are synthetic and aren't absorbed by your body as easily or in the same quantities as the vitamins and minerals in real food.
Meal replacement shakes also tend to be lacking in fiber, which is important for keeping you healthy and preventing constipation.
In addition, replacing meals with protein shakes or meal replacement shakes may be convenient, but it doesn't teach you how to make healthy choices on your own. When you eventually stop your protein shake diet, you may be unsure how to continue with a healthy eating plan that helps you sustain your weight loss.
Make Your Own Shakes
Your best bet for following a protein shake or meal replacement shake diet for a week is to make your own shakes. That way, you can fully control the ingredients going into it, and you'll know exactly what you're getting.
The key to making your own shakes is to add ingredients with different macronutrient profiles so you can optimize your intake of proteins, carbohydrates, fiber, fats, vitamins and minerals — and not just protein on its own.
To make your own shake, start with a base of grass-fed milk or your favorite nondairy alternative, like almond milk or coconut milk. Add a handful of frozen berries, a couple of handfuls of spinach or kale and a source of healthy fat, like liquid coconut oil or avocado.
- Centers for Disease Control and Prevention: "Attempts to Lose Weight Among Adults in the United States, 2013–2016"
- The American Journal of Clinical Nutrition: "The Role of Protein in Weight Loss and Maintenance"
- Diabetes Spectrum: "Meal Replacement Shakes and Nutrition Bars: Do They Help Individuals With Diabetes Lose Weight?"
- Today's Dietitian: "Liquid Meal Replacements"
- Mayo Clinic: "I'm Trying to Lose Weight. Could Protein Shakes Help?"
- Perspectives on Psychological Science: "Reducing Calorie Intake May Not Help You Lose Body Weight"
- Cleveland Clinic: "7 Tips for Choosing the Best Protein Powder for You"