How to Find the Best Meal Replacement Shakes for Intermittent Fasting

📌 Overview and Key Takeaways

This is a Certified Nutrition Coach’s guide on how to find the best meal replacement shakes for intermittent fasting.

Discover how to meet your daily protein needs before and after fasting.

Last Updated
Jul 21, 2026

Author and Medical Reviewer

Written by Jack, CNC

Jack is a National Academy of Sports Medicine Certified Nutrition Coach.

Disclaimer: This communication is for general informational purposes only and is not a substitute for personalized medical advice. Consult a licensed healthcare professional before making changes to your diet.

Are Meal Replacement Shakes Good for Intermittent Fasting?

Intermittent fasting involves restricting your eating schedule to certain hours of the day, or even going for a whole day without food.

There are many reasons why people do intermittent fasting, the most common being that it can help with weight loss.

Research suggests intermittent fasting is about as effective as a traditional low-calorie diet for weight loss (N Engl J Med, 2022), which makes sense because fasting is usually accompanied by a calorie reduction.

Simply reducing your eating to a narrow window does not necessarily promote weight loss, however.

In order to lose weight, you still have to burn more calories than you eat.

Meal replacement shakes, which are intended to replace the nutritional value of a meal, can be a great tool for someone who is using intermittent fasting to lose weight.

Here are a few of the benefits of drinking meal replacement shakes before and or after tasting:

• Increased Satiety: Meal replacements tend to be high in protein, which can increase satiety. Protein is the most filling macronutrient, so eating lots of it can help curb cravings and prevent overeating.
• Portion Control: Drinking a meal replacement shake can help you control the amount of calories you consume, which can also help you avoid overeating.
• Convenience: Meal replacements are convenient, making them an easy way to get fats, carbs, fiber, and protein in your diet. This can discourage snacking on junk, non-nutritive foods.

Keep in mind that you cannot drink meal replacement shakes while fasting, as doing so would break your fast.

It is also important to note that not all meal replacement shakes are created equal.

What Are the Best Meal Replacements for Intermittent Fasting?

Many meal replacements contain ingredients known to cause painful side effects and even long-term health problems.

Among these ingredients are food additives, dairy-based proteins, and protein concentrates and isolates.

🚫 Avoid Food Additives

Most meal replacements contain a cocktail of ultra-processed food additives.

And regularly eating emulsifiers, thickeners, flavorings, etc. can alter the composition and function of your gut microbiome (North Clin Istanb, 2019).

This can lead to gut dysbiosis, or an imbalance in his gut microbiota, which contributes to a wide range of chronic diseases, including obesity, type 2 diabetes, and even certain cancers (Int J Mol Sci, 2022; Int J Environ Res Public Health, 2018).

This might be because disruptions to your gut microbiome can affect the permeability of your intestinal barrier, allowing toxins to pass into your bloodstream (Gut, 2015).

⚠️ Here is a list of the most common food additives in meal replacements:

• acacia fiber
• acacia gum
• acesulfame potassium
• artificial flavors
• ascorbic acid
• aspartame
• calcium carbonate
• carrageenan
• cellulose gum
• dextrin
• dicalcium phosphate
• dipotassium phosphate
• erythritol
• gellan gum
• guar gum
• gum arabic
• inulin
• locust bean gum
• maltitol
• maltodextrin
• mono- and diglycerides
• ‘natural’ flavors
• rice bran extract
• rice dextrin
• rice hulls
• rosemary extract
• silica
• silicon dioxide
• sodium alginate
• soluble corn fiber
• sorbitol
• soy lecithin
• sucralose
• sunflower lecithin
• tocopherols
• tricalcium phosphate
• xanthan gum
• xylitol
• zinc oxide

As a rule of thumb, if you could not find an ingredient in nature or make it at home, it is a food additive.

🚫 Avoid Dairy-Based Proteins

Dairy-based proteins like whey and casein, although not an issue for everyone, can cause digestive issues too.

This is usually because they contain lactose, a sugar many people cannot fully digest.

But you might be sensitive to dairy-based proteins even if you are not lactose intolerant.

This is particularly true for casein protein, which forms a gel-like substance in your stomach that slows down digestion.

🚫 Avoid Protein Concentrates and Isolates

You should also consider avoiding protein concentrates and isolates.

Most meal replacements are made from one or both of these protein sources, which have been mechanically and/or chemically stripped of everything but the protein.

This includes the enzymes, fiber, and other natural digestive aids that help you break them down.

You therefore do not digest them in the same way that you do whole foods, which can affect your gut health.

In fact, studies show that regularly eating protein concentrates and isolates can disrupt your gut microbiome and cause the formation of toxic byproducts in your gut (Nutrients, 2018; Mol Nutr Food Res, 2024).

So instead of ultra-processed protein concentrates or isolates, look for whole food protein sources like egg whites and almonds.

They are easier to digest and absorb.

Order Samples to see for yourself.

Sources

1. New England Journal of Medicine (N Engl J Med). Calorie Restriction with or without Time-Restricted Eating in Weight Loss. 2022.
2. Northern Clinics of Istanbul (North Clin Istanb). Food additives and microbiota. 2019.
3. International Journal of Molecular Sciences (Int J Mol Sci). Intestinal Dysbiosis in Inflammatory Bowel Disease: Pathogenic Role and Potential Therapeutic Targets. 2022.
4. International Journal of Environmental Research and Public Health (Int J Environ Res Public Health). Microbiome-Based Hypothesis on Ivermectin’s Potential Effectiveness Against COVID-19. 2018.
5. Gut (Gut). Intestinal permeability – a new target for disease prevention and therapy. 2015.
6. Nutrients (Nutrients). The Impact of Protein Supplementation on Appetite and Energy Intake in Healthy Older Adults: A Systematic Review with Meta-Analysis. 2018.
7. Molecular Nutrition & Food Research (Mol Nutr Food Res). Plant-Based Protein Sources and Cardiometabolic Health: A Systematic Review and Meta-Analysis of Prospective Cohort Studies. 2024.

Editorial Guidelines

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This article was written by a Certified Nutrition Coach and reviewed by a Registered Dietitian. We rely on peer-reviewed research and trusted medical sources, and regularly update our content to ensure accuracy and clarity.