Does whey protein break intermittent fasting

Does Whey Protein Break Intermittent Fasting?

Andrew Brewer - Intermittent Fasting Expert

Written by Andrew Brewer. Updated on January 2023.

Medically reviewed and fact checked by our team.

Does whey protein break intermittent fasting

Protein is an essential building block for healthy muscles, and many fitness enthusiasts will integrate whey protein shakes into their diet when they’re looking to bulk up. Unfortunately, while it’s good for you, if you’re intermittent fasting, you want to skip the whey protein shakes during fasting windows. It will trigger an insulin response and break your fast. 

Why Can’t I Use Whey Protein While Intermittent Fasting?

During intermittent fasting windows, it’s not enough that you’re not eating any calories. You also have to avoid supplements that will prompt your body’s metabolic and insulin response. Either of these will break your fast, even if your caloric intake is zero.

Whey protein powder will do that when eaten alone or mixed with milk or water, so unfortunately, it will break your fast. During your intermittent fasting windows, stick to water, tea, and black coffee. Avoid adding any sugar or sweeteners to your drinks. Even zero-calorie sweeteners can trigger an insulin response in your body, which will break your fast. You will get the best results when you follow intermittent fasting rules strictly, so avoid the whey protein until your eating window. 

If you do break your fast prematurely, you can delay some of the healthy benefits, including kickstarting weight loss, increasing glucose tolerance, and healing the gut microbiome. Even the smallest of responses can hinder your progress, so it’s best to stick to your eating schedule and avoid the whey protein until you’re ready to break your fast.

When To Drink Whey Protein Shakes

Just because whey protein shakes break your fast doesn’t mean you should cut them out entirely. On the contrary, these shakes are great ways to ensure you hit your daily protein goals, especially if you struggle with food alone. 

One of the most common ways that you can break your fast is to drink a protein shake. This will be a gentle way to get your body ready to process food again. Check the nutritional label to see what’s in your whey protein powder. If you’re looking to break your fast, ensure it contains fiber in addition to other beneficial vitamins and minerals. For the best results, pair your shake with nuts. Healthy fats are essential to smoothly break your fast. Protein, fiber, and healthy fats are essential components of a balanced diet, and whey protein will help you with two of the three. Depending on what you mix it with, you may even be able to get the trifecta!

As you begin to plan how you’ll break your fast, start by calculating your daily protein needs. This is the minimum amount that you need to survive each day as you continue to build and maintain healthy muscles. You can eat more protein without little effect as long as you live an active lifestyle. Too much protein can hinder your progress if you lead a sedentary lifestyle. 

You’ll get the most benefits out of your protein if you space it out throughout the day rather than loading a single meal with your day’s protein intake, so keep that in mind as you plan when to drink your whey protein shake. You can drink multiple shakes per day, just don’t use them as a complete supplement to eating. They contain many nutrients, but your body may not feel full, so you could end up eating more than you’d like.

Ultimately, whey protein is an excellent way to ensure you hit your goals, ensuring you’re nutritionally prepared for fasting. What you eat is just as important as when you eat, so make sure to eat lots of protein during your eating windows to help kickstart your metabolism. 

Andrew Brewer

Andrew Brewer

Andrew Brewer started to give people the guidance that he never received when he was first starting. His goal is to make your goals achievable and to offer you only the best fasting apps that the internet has to offer. You're not on your own - Andrew and the entire family of reviewers at are here with you every step of the way!