Fasting On Protein Shakes

Written by Carina Fabia

Last updated on: Sep 25, 2022

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If you're looking to lose weight, you may have considered fasting. This is where you go for a set period of time without eating any food. You may be wondering if you can still drink protein shakes during a fast.

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In short, if your goal is to lose weight, fasting on protein shakes can be a great idea. It can help you stay fuller longer, boost your metabolism, help avoid unhealthy snacks, and still provide you with the protein you need to preserve your muscle mass. Let’s dig deeper into whether you can fast on protein shakes.

Combining Protein Shakes With Intermittent Fasting

If you're like most people, you probably think of protein shakes as a way to bulk up or gain muscle. Sedentary individuals require 0.8 grams of protein for each kg of their body weight, while athletes need even more (1). But when a normal diet cannot meet those requirements, protein supplements are an effective way to go. To learn the full pros and cons of protein supplements, go through this insightful study (2).

However, did you know that protein shakes can also be an effective tool for weight loss? In fact, combining protein shakes with intermittent fasting is a strategy that can help you lose weight and improve your overall health, especially for obese men and women (3). Scientific evidence reveals that the strategy led to a 3.3 kg of weight loss in a 12-week timeframe while also improving blood pressure and LDL (4).

Here's a closer look at how protein shakes and fasting can work together to help you reach your weight loss goals:

1. Protein Shakes Help You Stay Fuller Longer

One of the main reasons why protein shakes can be helpful for weight loss is that they help you feel fuller and longer. This is because protein takes longer to digest than other nutrients, such as carbohydrates. As a result, you'll be less likely to experience hunger pangs or cravings between meals.

2. Protein Shakes Can Boost Your Metabolism

Another way that protein shakes can help you lose weight is by boosting your metabolism. This is because protein requires more energy to digest than other nutrients. As a result, your body will burn more calories as it breaks down the protein in your shake.

3. Protein Shakes Can Help You Preserve Muscle Mass

If you're trying to lose weight, you might be concerned about losing muscle mass along with fat. However, protein shakes can help you preserve muscle mass while you're losing weight, which is why they’re so popular among gym goers (5). This is because protein is essential for building and maintaining muscle tissue. If you’re an athlete, you can then experience improved performances (6).

4. Protein Shakes Make it Easy to Get the Protein You Need

Getting enough protein is essential for weight loss, but it can be difficult to get enough from your diet alone. This is where protein shakes come in handy. Protein shakes make it easy to get the protein you need without having to eat large amounts of food.

5. Protein Shakes Can Help You Avoid Unhealthy Snacks

If you're trying to lose weight, it's important to avoid unhealthy snacks. However, sometimes you might find yourself reaching for a snack because you're feeling hungry. If this happens, protein shakes can be a healthy alternative to unhealthy snacks.

Tips to Use Protein Shakes While Fasting

Determine Your Goal for Fasting

What are you hoping to achieve through fasting? Whether it's weight loss, detoxification, or increased spiritual awareness, know your goal before beginning any type of fast. If you aim to increase your blood insulin levels and lose weight, intermittent fasting on protein shakes is an effective tactic. Not only do protein shakes contain protein, but they also often contain sugar and some carbohydrates.

Consider the Type of Fast

Before you start intermittent fasting on protein shakes, it's important to consider the type of fast you're undertaking. Are you doing a total fast, where you consume no food or drink for a set period of time? Or are you doing a partial fast, where you consume only certain foods and drinks while avoiding others?

If you're doing a total fast, then obviously, protein shakes are off the table. But if you're doing a partial fast, then protein shakes can be a part of your plan as long as they don't contain any forbidden foods or drinks.

Don't Take Protein Shake During the Fasting Window

If you're doing intermittent fasting, you will likely have a set window of time when you can eat and drink, followed by a period of fasting. During the fasting window, you should not consume any calories, including protein shakes. Doing so will defeat the purpose of fasting.

Even if you mix the protein powder with water, your consumption will still be around 30 grams, which means more than 100 calories. Hence, it will break your fast. So, it's best to consume a protein shake during the eating window.

Use Protein Shakes as Meal Replacement

Protein shakes can be a convenient way to get all the nutrients you need in one meal. If you're doing intermittent fasting, try using protein shakes as a meal replacement during your eating window. That way, you can save time and ensure that you're getting all the nutrients your body needs. Just be sure to choose a protein powder that is low in sugar and carbohydrates.

Choose the Right Protein Powder

Not all protein powders are created equal. In fact, there are different types of the protein itself (7). If you're going to use protein shakes while fasting, be sure to choose a powder that is high in protein and low in sugar and carbohydrates. A good rule of thumb is to choose a powder that has at least 20 grams of protein per serving.


Protein powder is best known for topping up protein levels to take advantage of the concrete associations between protein supplementation and resistance training to improve strength and develop lean muscle mass (8). However, fasting on protein shakes is another great way to use this supplement. It provides a great way to detox and lose weight quickly. It’s also a good way to give your digestive system a break. 

If you want to try fasting on protein shakes, be sure to follow the tips explained above and consider drinking plenty of water and eating healthy foods when you break your fast. We truly hope that this guide helps you achieve your fitness goals without facing any complications.

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