Does a Protein Shake Break a Fast?

Yes, a protein shake will definitely break a fast. However, it’s a great thing to sip on once the fast is over. Here’s what you need to know.

Does a Protein Shake Break a Fast?

A protein shake will typically contain pure protein. Sometimes you’ll also find some sugar or fat added in. However, let’s assume your protein shake is a pure protein without added sugar or fat. Will your protein shake break a fast?

Whether or not something breaks a fast comes down to if it causes the body to release the storing hormone insulin. The main fat burning, weight loss and wellness perks of Intermittent Fasting come from the fact that you’re not releasing insulin while you’re fasting. So if you start releasing insulin in response to something you consume during the fast, you’re no longer receiving the health and weight loss perks and have therefore broken your fast.

Insulin is primarily released when we eat food. Carbohydrates cause the biggest release and protein causes a relatively smaller release. This means if you consume protein or carbohydrates during your fast, you will break your fast. On the other hand, fat has zero impact on insulin. This is why some fats in your coffee (like with the Keto Coffee recipe) can be consumed during the fast without breaking your fast.

Considering a protein shake is a pure protein source, it will break a fast. Not to mention if it has any sugar added in, it will cause an even bigger insulin spike.

Pssst – wondering what type of fasting is best for your goals? Click below for my free Intermittent Fasting Schedule quiz to find out!

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The 21 Day Intermittent Fasting Program

The 21 Day Intermittent Fasting Program provides step-by-step strategies to help you use Intermittent Fasting with delicious, protein-packed meals to support fat loss, reduce hunger, and boost gut health.

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The Best Protein Shakes For Intermittent Fasting

However, this doesn’t mean that you want to cut your protein shake out of your Intermittent Fasting routine – you just wan to have it at the right time: when you break your fast. Consuming enough protein from complete protein sources is crucial for achieving a body recomposition goal where you’re losing body fat while maintaining muscle mass.

Pairing your protein with high quality fats is even more important if you’re also working out while Intermittent Fasting. One study found that protein plus fat was better at helping the muscles recover from a workout than just protein alone.(1)

Checkout 5 of my favorite high quality protein, fat and fiber protein shakes below. Break your next Intermittent Fast with these!

peanut butter protein smoothie with cacao nib topping

Vanilla Peanut Butter Smoothie

This smoothie is packed with high quality protein to help repair your muscles post workout and keep you satisfied during your next fasting window.

Grab the recipe HERE.

Turmeric Lemon Detox Smoothie

On top of protein, you also get the added liver detoxification perks of Turmeric.

Test it out HERE.

healthy chocolate peanut butter smoothie with cinnamon

Chocolate Collagen Smoothie

Collagen is not a complete protein source, so we’ve added collagen in addition to a complete protein source in this smoothie to get EVERYTHING you need!

Make it with THIS recipe.