Does drinking a protein shake break intermittent fasting?

Intermittent fasting has become increasingly popular in recent years for its ability to show quick results, particularly in weight loss. The practice of intermittent fasting involves fasting during a portion of the day or week while consuming food and drinks during the remaining hours. However, some people have concerns about whether drinking a protein shake could break their intermittent fasting. In this post, we will dive into the details to determine if drinking a protein shake breaks the fast.

What is Intermittent Fasting?

Intermittent fasting is a dietary pattern, where individuals consume their meals in specific periods of time, or “windows”. The primary goal of intermittent fasting is to reduce the amount of food a person eats during their day, which in turn can lead to weight loss. There are several different types of intermittent fasting, including:

16/8 Method

This entails eating meals only during an eight-hour window every day and fasting for the remaining 16 hours.

5:2 Diet

This entails consuming a usual amount of calories for five days and restricting intake to 500-600 calories on the other two days.

Alternate-Day Fasting

This entails fasting every other day and consuming only up to 500 calories on fasting days.

The Role of Protein Shakes in Intermittent Fasting

Protein shakes have become a popular supplement for those who are looking to build muscle, lose weight or improve their overall nutrition. Protein supplements are high in protein, which makes them a convenient source of protein required for muscle growth and maintenance. However, some people are concerned that drinking protein shakes can break their fast during intermittent fasting.

Does drinking a protein shake break the intermittent fast?

Technically, consuming a protein shake does break a fast since it contains calories. However, it is essential to understand that the benefits of intermittent fasting come from limiting the timing of food consumption rather than avoiding calories altogether. The body uses energy during fasting hours, so consuming food or drinks with fewer calories will keep your body in a fasting state.

How Protein Shakes Affect the Body During Intermittent Fasting

Protein shakes supply your body with the necessary nutrients to support muscle protein synthesis, helping rebuild muscle fibers. But when consumed during the fasting window, it may reduce the positive impact of fasting. Protein intake during fasting can kickstart the digestive process and shift your body out of the fasting state. Fasting generally lowers blood sugar and insulin levels, leading to an increase in human growth hormone levels. When you consume protein, insulin levels will increase, halting the release of stored glucose, which in turn will lower the levels of Human Growth Hormone.


Drinking a protein shake during the eating window of the intermittent fasting plan can be highly beneficial for those looking to build muscle. However, it should be noted that consuming a protein shake during a fasting window will still break the fast. It is safe to consume protein shakes in moderation, but it’s important to always consult your physician before beginning any new diet or exercise regimen. Just remember to keep your goals in mind and adjust your diet and workout plans accordingly.

If you’re looking to purchase a protein shake, ensure that it doesn’t contain any sweeteners, flavorings, or any other ingredients that spike insulin levels. The best way is usually to prepare your protein drink at home, using natural protein powders. Remember, be mindful of how many calories you consume during the day. A protein shake does contain calories, and it can easily overstep the limit for your daily fast if you’re not careful. Finally, A protein shake should never serve as a replacement for a meal, as it lacks fiber, healthy fats, and other nutrients that are usually found in whole foods.

External Link

For further information on the effects of protein shakes during intermittent fasting, check out this article from Healthline.
Intermittent Fasting and Protein: How Protein Affects Your Fasting Goals.


How much protein will break a fast?

Intermittent fasting has become a widely popular method used to manage weight, improve metabolic health, and overall well-being. During the fasted state, the body undergoes several physiological changes, such as increased fat burning, improved insulin sensitivity, and autophagy. However, one of the common questions among followers of intermittent fasting is how much protein will break a fast?

Protein is an essential macronutrient that is necessary for muscle repair, growth, and maintenance. While it is vital for overall health, consuming protein during a fasting period can disrupt the physiological state of fasting. The research on the topic is limited, and the amount of protein that can break a fast varies among individuals. A good rule of thumb is to stick to less than 1 gram total of carbohydrates and protein during the fasted state to help ensure that you won’t break your fast.

It is essential to understand the difference between different types of fasting. Some fasting methods such as water fasting, dry fasting, and juice fasting prohibit consuming any calories, including protein. In contrast, other methods, such as the 16/8 method, allow consuming calories during the eating window. However, it is recommended to limit protein intake when following the 16/8 method to ensure that the body remains in the fasted state.

Protein sources that are easily digestible, such as whey protein, casein protein, and branch-chain amino acids (BCAAs), should be avoided during the fasting period as they can spike insulin levels. Insulin is a hormone that signals the body to stop burning fat and start storing it. Therefore, consuming protein sources that spike insulin can disrupt the physiological state of fasting and break the fast.

How much protein will break a fast varies among individuals, and there is no one-size-fits-all answer. To stay in the fasted state, it is recommended to stick to less than 1 gram total of carbohydrates and protein. Moreover, it is crucial to select protein sources that do not spike insulin levels, such as collagen protein, bone broth, and vegetable-based protein powders. Before starting any fasting method, it is recommended to consult with a healthcare professional to ensure it is safe and suitable for individual needs.

What happens when you break a fast with protein?

Intermittent fasting has gained widespread popularity in recent years, with many individuals using it as a weight loss strategy and for its potential health benefits. However, when it comes to breaking a fast, the choice of food can play a critical role in how the body responds to the reintroduction of nutrients after a period of fasting.

One strategy that has been suggested is breaking a fast with protein-rich foods. This is because protein has been shown to have a minimal effect on blood sugar and insulin levels when compared to carbohydrates or fats. This means that protein can help avoid any significant responses in glucose that could increase glycemic variability and insulin levels throughout the day.

Also, consuming protein during a meal can increase the levels of hormones that promote feelings of fullness and satisfaction, such as peptide YY (PYY) and glucagon-like peptide-1 (GLP-1). These hormones help reduce hunger and prevent overeating, making it easier to stick to a healthy eating plan.

Moreover, protein is essential for maintaining and building muscle mass, and breaking a fast with protein can help meet the body’s increased demand for protein synthesis after a period of fasting. Additionally, including protein in the first meal after a fast can also help increase metabolism and the number of calories burned during digestion.

While there is no one-size-fits-all approach to breaking a fast, incorporating protein into the first meal after a fast can be beneficial for controlling blood sugar levels, reducing hunger, promoting fullness, and supporting muscle growth and metabolism.

What can you drink while intermittent fasting?

Intermittent fasting is a popular lifestyle trend that involves restricting calorie intake for a set period. This method has gained popularity due to its numerous perceived health benefits, including weight loss and improved metabolism. One of the main questions people have about intermittent fasting is what they can drink while following the fasting schedule.

When it comes to what you can drink during intermittent fasting, the rule is relatively straightforward – only calorie-free beverages are permitted during the fasting period. This means that you cannot consume any food or drinks that contain calories, including fruit juice, milk, or your favorite soda. Instead, you should stick to drinking water, black coffee, or unsweetened tea.

Water is the best option for staying hydrated when you are following an intermittent fasting regimen. It is calorie-free, and it helps to keep your hunger levels under control. It also helps to flush toxins out of your body and support your metabolism.

Black coffee is another popular drink for those following the intermittent fasting method. Coffee is known to boost metabolism and can help to suppress appetite and reduce hunger pangs. However, be cautious with the amount you consume, as too much caffeine can lead to jitteriness, anxiety, and insomnia.

Unsweetened tea is also an excellent beverage to consume while intermittent fasting because it is low in calories and can help to reduce appetite. If you find plain tea too bland, you can add lemon or herbs such as mint to enhance its taste.

To reiterate, any other calorie-free drinks such as soda, or energy drinks alike, are not allowed during the fasting period. While fasting, it is essential to stick to only zero-calorie fluids to ensure you stay on track and receive the maximum health benefits from your fasting schedule.

While intermittent fasting, you can drink water, black coffee, and unsweetened tea. All other beverages containing calories, such as fruit juice or milk, are not allowed during the fasting period. Drinking lots of water is necessary to ensure that you stay hydrated, while black coffee and tea can help to reduce hunger pangs and provide some extra benefits.

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