How to Find the Best Protein Powder for Intermittent Fasting

📌 Overview and Key Takeaways

This is a Dietitian’s guide on how to find the best protein powder for intermittent fasting.

Discover how to easily supplement your protein intake while intermittent fasting.

Last Updated
Jan 28, 2026

Author and Medical Reviewer

Written by Kayla Kamen, MS, RD

Kayla Kamen is a Registered Dietitian with a MS in Nutrition.

Medically reviewed by Jennifer Fossett, PA-C

Jennifer Fossett is a Physician Assistant with a BA in Nutritional Sciences.

Protein Powder for Intermittent Fasting

Is Protein Powder Good for Intermittent Fasting?

Intermittent fasting is a dietary pattern characterized by recurring intervals of eating and fasting.

It does not restrict specific food groups or count calories, it just dictates when you consume your meals.

For example, the 16/8 method includes a 16-hour fast followed by an 8-hour eating window.

This might mean you skip breakfast and consume all your daily meals between 12 and 8 p.m.

The goal of intermittent fasting is to extend the amount of time between your last meal of the day and your first meal the following day.

Doing so causes your insulin levels to drop and your body to start burning stored fat for energy.

This pattern of eating has gained popularity due to its potential health benefits (N Engl J Med, 2019), which include weight loss, improved insulin sensitivity, and reduced inflammation.

Eating enough protein is important when practicing intermittent fasting for several reasons, including:

1. Satiety: Protein is more satiating than carbs or fats, meaning it makes you feel fuller for longer (Am J Clin Nutr, 2008). This, in turn, reduces cravings during fasting periods.
2. Thermogenesis: Eating protein increases thermogenesis (J Am Coll Nutr, 2004), or your metabolic rate and energy expenditure, which can help with weight loss.
3. Muscle preservation: When you are in a calorie deficit during intermittent fasting, there is a risk of muscle loss. Consuming enough protein helps preserve muscle mass (Nutrients, 2019).

Keep in mind that you should try to meet your protein needs by eating foods like dairy, eggs, fish, legumes, meat, nuts, and seeds.

If you are unable to easily do so, however, perhaps due to lifestyle or dietary restrictions, protein powder can help you fill in the gaps.

It can easily be added to smoothies, oatmeal, and other recipes, or mixed with just milk or water to make a protein shake.

When you add protein powder to your diet while intermittent fasting will depend on your personal preferences and the specific fasting protocol you are following.

That said, eating a high protein meal or snack at the end of your eating window can help curb cravings during the fasting period.

So consider adding protein powder to your diet just before you start to fast.

And note that you may not use protein powder while fasting, as doing so would break your fast.

What Is the Best Protein Powder for Intermittent Fasting?

The type of protein powder that you add to your diet is not particularly important.

That is, as long as you are eating a balanced diet (getting protein from a variety of sources), any type of protein powder can help you fill in gaps in your diet.

Not all protein powders are created equal, however.

Many protein powders contain ingredients that can cause painful side effects and even long-term health problems.

Among the most problematic ingredients are food additives, dairy-based proteins, and protein concentrates/isolates.

🚫 Avoid Food Additives

Regularly eating food additives like emulsifiers, thickeners, artificial sweeteners, and other ultra-processed additives can alter the composition and function of your gut microbiome (North Clin Istanb, 2019).

Over time, this can lead to gut dysbiosis, which is associated with a wide range of chronic health problems, including metabolic, inflammatory, autoimmune, neurological, and gastrointestinal diseases (FEBS J, 2020).

Mechanistically, dysbiosis can influence chronic disease through effects on mucosal immunity, inflammation, intestinal barrier integrity, and altered production of metabolites such as short-chain fatty acids.

⚠️ Here is a list of the most common food additives in protein supplements:

• 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 cannot find it in nature or make it at home, it is probably 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 individuals with sensitive stomachs 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 might also want to avoid ultra-processed protein concentrates and isolates.

Most protein supplements are made from one or both of these ultra-processed 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 your gut break them down.

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

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

You should thus look for protein supplements made from whole food protein sources like egg whites and almonds, which are easier to digest and absorb.

Order Samples to see for yourself.

Sources

1. New England Journal of Medicine (N Engl J Med). Effects of Intermittent Fasting on Health, Aging, and Disease. 2019.
2. The American Journal of Clinical Nutrition (Am J Clin Nutr). Protein, weight management, and satiety.. 2008.
3. Journal of the American College of Nutrition (J Am Coll Nutr). The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review.. 2004.
4. Nutrients (Nutrients). Dietary Protein and Muscle Mass: Translating Science to Application and Health Benefit. 2019.
5. Northern Clinics of Istanbul (North Clin Istanb). Food additives and microbiota. 2019.
6. The FEBS Journal (FEBS J). The mutual interplay of gut microbiota, diet and human disease.. 2020.
7. Nutrients (Nutrients). Effect of a Protein Supplement on the Gut Microbiota of Endurance Athletes: A Randomized, Controlled, Double-Blind Pilot Study. 2018.
8. Molecular Nutrition & Food Research (Mol Nutr Food Res). In Vitro Fermentation of Animal and Plant Protein Isolates by the Human Gut Microbiota Under High and Low Carbohydrate Conditions.. 2024.

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