Should You Break A Fast With A Protein Shake? (Here’s How)

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When you’re fasting you’re going without key nutrients for performance and recovery, so you may be wondering if a protein shake to break your fast is the best choice for helping your body to recover and refuel properly.

Should you break a fast with a protein shake? Yes, breaking a fast with a protein shake is ideal to help supply your body with amino acids for muscle retention and recovery after being deprived of them while fasting. In addition to protein, your shake should contain a source of dietary fat and micronutrients (vitamins and minerals).

Although you can break your fast with a protein shake, there is a certain type of protein that is better than others, and additional factors at play that you should consider before breaking your fast.

Key Takeaways

  • Consuming any type of protein while fasting will break your fast.
  • Whey protein is the best protein source for breaking your fast because it is absorbed more quickly than other types of protein.
  • The amount of protein you need to break your fast will depend on your daily protein target and the number of meals you eat during your ‘feeding window’.
  • Fasts longer than 24 hours require a refeeding protocol that prioritizes electrolytes, liquid calories, and a reduced intake.

Do Protein Shakes Break A Fast? 

protein shake

Protein shakes do break a fast because they have approximately 120-150 calories per serving and require your digestive system to break down the protein into amino acids to be absorbed.

Breaking a fast is generally characterized by the number of calories that are consumed (>10 calories) and spikes in insulin, which happens upon the ingestion of carbs and protein.

Therefore, even taking a BCAA or collagen product with little to no calories can be considered “breaking your fast”.

Is It Good To Break A Fast With A Protein Shake?  

Breaking your fast with a protein shake is a good idea because while you’re fasting you’re not getting a steady supply of amino acids to support muscle retention and recovery. 

Your second priority when breaking a fast should be a protein source to ensure you’re preserving as much muscle as you can (your first priority should be electrolytes which I discuss later on).

However, a source of protein by itself likely isn’t enough after having fasted so it’s best to pair it with a source of carbs, fats, and micronutrients. You can do this by adding other foods to your protein shake.

“If you’re going to have carbs, ensure that they’re balanced with protein and fat. A salad with protein, eggs with avocado and vegetables, a homemade protein shake, or a leftover protein and roasted veggies could all work as meal number one.”

Ali Miller R.D., L.D., CDE, registered dietitian, and functional medicine practitioner

Does The Type of Protein Matter When Breaking A Fast?

When you’re breaking your fast the best type of protein you should choose is whey protein because it has the fastest absorption rate. The sooner your body can break down the protein into amino acids, the sooner you’ll provide your body with fuel.

However, if you don’t have whey protein then any other protein source will do (whole foods or other protein powders). It’s better to have a slower digesting source of protein than none at all.

What To Watch Out For When Breaking A Fast With A Protein Shake


If you’re going to break a fast with a protein shake then it should be with a protein that you’ve used before without any digestive issues. 

You should never consume something for the first time when breaking your fast because you won’t know how you respond to it, and your digestive system will be extremely sensitive when you break your fast.

Be sure to test any protein powder that you want to use before you begin fasting so that you know you can tolerate it.

Typically artificial sweeteners, lactose, or dairy in general are the main culprits that cause digestive issues for those with sensitive stomachs.

Digestive symptoms caused by these sensitivities will be heightened following a fast (especially a longer fast) because your body won’t be producing as many digestive enzymes to help break down food more easily.

How Much Protein Should You Have When Breaking A Fast?

Those who are intermittent fasting (a set eating window and fasting outside of this eating window) can keep a similar protein intake to those who aren’t fasting by spreading their daily protein intake evenly across each meal.

A typical daily protein intake is 0.8 to 1 gram of protein per pound of bodyweight, so if you weigh 160lbs then you could consume between 128 to 160 grams of protein per day.

If you’re having 4 meals per day then you can aim to have 32 to 40 grams of protein per meal (including the meal that breaks your fast).

Those who are doing an extended fast (without eating windows) like a 3 or 5-day fast can also distribute their protein intake evenly between meals. However, they will require smaller, more frequent meals throughout the day. 

These individuals will need 1 to 1.2 grams of protein per pound of bodyweight per day because they’ve likely already lost muscle mass from an extended period without food.

For example, if you weigh 160lbs, your protein target could be 192 grams of protein per day which can be split across 8 meals, each with 24 grams of protein.

Additionally, any food consumed within the first 48 hours after fasting should be liquid calories because solid food will be too hard to digest. Therefore choosing a protein shake for your protein source is the best option when breaking a longer fast.

Other Criteria To Consider When Breaking A Fast?

Other considerations when breaking a longer fast (>24hrs) are:

  • Avoiding Alcohol and Processed Foods. Steer clear of alcohol and processed foods that are high in sugar and sodium for at least 72 hours after breaking your fast to encourage adequate hydration and electrolyte replenishment. 
  • Keeping Calorie Intake Low For 24 to 48 Hours. Limit your calorie intake to 50% of your normal intake for 1 to 2 days to give your digestive system time to properly prepare to digest food again. This will drastically reduce your chances of digestive discomfort.
  • Choosing Liquids Over Solids For 48 Hours. To help your digestive system adapt more easily to the incoming calories, start with a liquid diet for the first 48 hours. Liquids are much easier to digest than solid foods.

For more in-depth information on breaking a fast safely, check out my 3-day and 5-day refeed guides.

Protein Shake Recipe For Breaking A Fast

In addition to this protein shake, I recommend taking an electrolyte supplement like this one to help replenish your electrolytes following an extended fast. If you’re someone who is only intermittent fasting, then this isn’t required.

The following protein shake recipe is tailored to someone who weighs 160, is eating 6 meals per day, and has been fasting for more than 24 hours. 

To make this protein shake recipe specific to your needs you can adjust the amount of protein in this shake based on your bodyweight and how many meals you plan to eat per day.

Peanut Butter & Jelly Inspired Protein Shake

Peanut Butter & Jelly shake


  • 1 scoop of vanilla whey protein powder
  • 1 cup of almond milk
  • 1 tbsp of peanut butter
  • 1 cup of frozen mixed berries
  • Optional: 1 tsp of sugar-free jam


Add all ingredients to a blender. Blend until all liquids are well-combined. 

Nutritional Information:

329 calories, 30 grams of protein, 13 grams of fat, and 23 grams of carbs (without jam).

Best Protein To Break A Fast With

I recommend using Transparent Lab’s Grass-Fed Whey Protein Isolate powder to break your fast because it absorbs quickly, it has one of the highest percentages of protein per scoop that I’ve seen (meaning it’s not full of fillers), and it is sweetened with stevia instead of artificial sweeteners.

This whey protein is a great option for those who find that they’re sensitive to other whey protein powders because it has high-quality ingredients, it is free of artificial colors and flavors, and it is virtually lactose-free.

Transparent Lab Whey Protein Isolate

Transparent Labs Whey Protein

The Transparent Labs Grass-Fed Whey Isolate is the #1 protein that recommends.


Beck, K. L., Thomson, J. S., Swift, R. J., & von Hurst, P. R. (2015). Role of nutrition in performance enhancement and postexercise recovery. Open access journal of sports medicine, 6, 259–267.

Rietman A, Schwarz J, Tomé D, Kok FJ, Mensink M. High dietary protein intake, reducing or eliciting insulin resistance? Eur J Clin Nutr. 2014 Sep;68(9):973-9. doi: 10.1038/ejcn.2014.123. Epub 2014 Jul 2. PMID: 24986822.

Williamson, E., & Moore, D. R. (2021). A Muscle-Centric Perspective on Intermittent Fasting: A Suboptimal Dietary Strategy for Supporting Muscle Protein Remodeling and Muscle Mass? Frontiers in Nutrition, 8, 640621.

Mehanna, H. M., Moledina, J., & Travis, J. (2008). Refeeding syndrome: what it is, and how to prevent and treat it. BMJ (Clinical research ed.), 336(7659), 1495–1498.

About The Author

Amanda Parker

Amanda Parker is an author, nutrition coach, and Certified Naturopath.  She works with bodybuilders, Olympic weightlifters, and powerlifters to increase performance through nutrition and lifestyle coaching.

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