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Whether you read my article How To Use Protein Shakes For Weight Loss or not, you might be wondering if protein shakes fill you up and how that might help (or hurt) your nutrition goals.
A protein shake is more or less filling depending on several factors including the overall volume, the nutritional profile (protein, calorie, & fiber content), thickness, and speed of digestion of the shake. These can be influenced by the amount and type of protein powder as well as other ingredients in the shake.
The best tips to follow for protein shakes will depend on whether your goals are for weight loss or weight gain, so it’s important to know how to make protein shakes either more or less filling for your specific needs.
- Protein powders have been studied extensively and have been linked to better overall metabolic health and body composition in the long term, largely due to the satiety of protein.
- You can easily make protein shakes more or less filling, depending on your goals (adjusting the type of protein used, fiber content, and overall volume of the shake).
- Protein powders are a great way to help you meet your overall daily protein target, but they are not as filling or nutritious as whole foods and you should limit your intake to no more than ⅓ of your total protein requirement.
Science Behind Protein Shakes & Satiety
The great news is that there have been many, many studies on protein and satiety, including studies that specifically look at protein shakes and not just protein in general.
I’ll summarize the key findings below.
Study 1: Protein “Pre-load”
In this study, participants who were free to eat as much as they wanted consumed 19% fewer calories after they were given a “protein pre-load” of 400mL of protein shake (53g of protein and 218 calories) compared to 400mL of water.
This shows that prioritizing protein intake, specifically in the form of a shake, can reduce calorie consumption later in the day.
Study 2: High Protein, High Fiber Shakes & Fullness
The women in this study felt fuller for longer and it took them longer to feel hungry again after they had a high protein, high fiber shake (120 calories) compared to a low protein, low fiber shake with the same number of calories.
This shows that both the protein and fiber content of a shake have an impact on its satiety.
Study 3: Protein Shake Thickness & Satiety
This study introduces the term “phantom fullness” to describe the fact that the participants felt fuller after drinking a thicker protein shake (100 calories), even though the calorie content was significantly less than a thinner protein shake (500 calories).
Study 4: Protein And Weight Loss
In this study, the authors noted “additional protein consumption results in a significantly lower body weight regain after weight loss, due to body composition, satiety, thermogenesis and energy inefficiency.” Their suggestion was to prioritize protein intake when decreasing calorie intake.
Protein shakes are a great way to do this because protein powder is nearly all protein (80-90% by weight), allowing you to increase your protein intake but with minimal additional calories.
Study 5: Protein, Weight Management & Satiety
This study had several great benefits associated with increased protein intake:
- Increased satiety: they noted that protein is more satiating than carbohydrates or fat
- Increased thermogenesis: you burn more calories when you eat protein because it takes more digestive effort to break down protein
- Maintaining or increasing lean muscle mass, which improves metabolism and allows you to burn more calories throughout the day, including at rest
Protein powder can be a great way to help you hit your daily protein targets if you struggle to eat enough protein from whole foods alone.
6 Factors That Make Protein Shakes More Or Less Filling
There are six key factors that make protein shakes more or less filling:
The overall size of a protein shake will make it more or less filling, since the amount of space something takes up in your stomach will impact how full you feel. We all have “stretch receptors” in our stomachs that help to let us know when we are full.
A high-volume protein shake is more filling than a low-volume protein shake.
2. Protein Content
Since protein is the most satiating macronutrient, the more protein a protein shake has, the more filling it will be, if all other elements are the same.
You can change the protein content of a shake by changing the amount of protein powder you use, and/or what you mix the protein powder with (e.g. milk or water).
- Related Article: 1 or 2 Scoops of Protein Powder: How Much Is Right For You?
3. Calorie Content
All other things being equal, a protein shake with a higher calorie content will also be more filling than a lower-calorie content protein shake. Calorie content will be impacted by what ingredients you use, and how much of each.
For example, the type of liquid you use can add a lot of calories (like whole milk, chocolate milk, or juice), or little to no calories (almond milk or water).
4. Rate Of Digestion
The more quickly you digest a protein shake, the less filling it will be. Different types of protein powder digest at different rates. I’ll discuss the specific types of protein powders in the sections that follow.
Plus, fat and fiber are slow to digest, so adding fat and/or fiber to a protein shake will make it more filling.
Some protein powders have added thickening agents like various types of gums. Thicker protein shakes are more filling than thinner protein shakes.
6. Fiber Content
As mentioned, fiber is slow to digest and takes up space in your stomach, so a protein shake with a higher fiber content will be more filling than a protein shake with a lower fiber content.
Based on these six factors, I’ll share my recommendations to make protein shakes either more or less filling, depending on what is most important to you.
Ways To Make Protein Shakes More Filling
Generally, when people are looking to lose weight, they want their protein shakes to be more filling so that it is easier to manage an overall calorie deficit without feeling overly hungry or dealing with cravings.
To make protein shakes more filling, here are my top tips to keep you feeling full for hours:
- Use more liquid: since liquid takes up space in your stomach and contributes to feelings of fullness, use a larger amount of liquid so that your shake has more volume and is more filling.
- Use more protein: you can add another scoop of protein powder, and/or mix your protein shake with a liquid that contains protein (milk), or add another source of protein like egg whites or Greek yogurt to make your protein shake more filling.
- Add calories: if you don’t need to worry about a calorie deficit, you can make a protein shake more filling by adding more calories to it, especially slow-digesting choices like fat – a big spoonful of peanut butter is a great way to make a shake more filling, and can help if you have weight gain goals.
- Add ice: adding ice cubes is another great way to increase the volume and thickness of your protein shake so that it is more filling, but without any added calories if you need to stay in a calorie deficit.
- Use slow-digesting protein powder: casein protein powder, or a blend that includes both whey and casein protein is the slowest-digesting form of protein powder. It will take several hours to digest a scoop of casein protein.
- Use a high-speed blender: a high-speed blender will help whip air bubbles into your protein shake, which will take up space in your stomach and make you feel full.
- Add thickeners: look for protein powders that include thickeners like xanthan gum, carrageenan, or guar gum, or add your own. I like to add ¼ tsp of xanthan gum to make a thick, creamy protein shake with a texture like a milkshake.
- Add fiber: fiber is another way to fill you up without adding many calories, so I like to add high-fiber fruits, vegetables or legumes like blackberries, cauliflower and white navy beans (they have a mild flavor so they don’t change the taste of my shake, but they add beneficial fiber).
Related Article: Ways To Add Fiber In Protein Shakes (With Recipes)
Ways To Make Protein Shakes Less Filling
If you need to ingest more calories and protein without feeling uncomfortably full, such as when you have weight gain goals, here are my top tips to make protein shakes less filling.
Note: Naturally, these are basically the opposite of all my tips to make protein shakes more filling:
- Use less liquid: since liquid takes up space in your stomach and contributes to feelings of fullness, use a smaller amount of liquid so that your shake has less volume and is less filling.
- Use less protein: to make a protein shake less filling, consider using only 1 scoop of protein powder, and avoid mixing with liquids that contain protein.
- Use fast-digesting protein powder: whey hydrolysate or isolate are the fastest-digesting forms of protein powder so they will be quickly absorbed and won’t leave you feeling full for hours.
- Stir, don’t shake: when you vigorously shake or use a high-speed blender to make your protein shakes, you will incorporate more air, causing foaminess that can fill you up. Stir gently to dissolve your protein powder instead so that you can avoid these bubbles.
- Avoid thickeners: ingredients like xanthan gum, carrageenan, or guar gum are all thickeners that can make your protein shake too filling.
- Avoid added fiber: since fiber can fill you up without adding calories, make sure that your protein powder does not contain added fiber, and don’t add ingredients that are high in fiber such as fruit, vegetables, or legumes. Plant-based protein powder is more likely to contain fiber than whey protein powder.
1. A More Filling, Low-Calorie Protein Shake
215 calories: 36g protein, 12g carbs (8g fiber), 3g fat
- 2 cups of water
- 1.5 scoops (~45g) vanilla whey-casein protein powder (I used PEScience Gourmet Vanilla)
- 1 tsp psyllium husk
- ¼ tsp xanthan gum
- 2 large handfuls of baby spinach
- 1 handful of ice cubes
Add all ingredients in the order listed to a high-speed blender and process until smooth and creamy.
2. A More Filling, High-Calorie Protein Shake
660 calories: 44g protein, 68g carbs (12g fiber), 26g fat
- 2 cups of whole milk
- 1 scoop (~30g) vanilla whey-casein protein powder (I used PEScience Peanut Butter Cookie)
- 1 tsp psyllium husk
- ¼ tsp xanthan gum
- 1 large banana
- 1 tbsp smooth peanut butter
- 1 handful of ice cubes
add all ingredients in the order listed to a high-speed blender and process until smooth and creamy.
3. A Less Filling, Low-Calorie Protein Shake
130 calories: 28g protein, 3g carbs (1g fiber), 1g fat
- 1 cup of water
- 1 scoop (~30g) peppermint whey isolate protein powder (I used Transparent Labs 100% Grass-Fed Whey Protein Isolate in Peppermint Hot Chocolate)
stir the protein powder into the water until fully dissolved.
4. A Less Filling, High-Calorie Protein Shake
350 calories: 29g protein, 62g carbs (0g fiber), 0g fat
- 1 cup of apple juice
- 1 scoop (~30g) vanilla whey isolate protein powder (I used Transparent Labs 100% Grass-Fed Whey Protein Isolate in French Vanilla)
- 2 tbsp liquid honey
stir the protein powder into the juice until fully dissolved, then stir in the honey.
Do Protein Shakes Fill You Up Like Food?
Generally no, protein shakes do not fill you up in the same way as whole food. Protein shakes have already undergone significant processing, first to get to protein powder, and next in the form of shaking or blending, meaning that your digestive system has less work to do.
When you start with whole food, you have to chew thoroughly first, and then swallow the food. This is especially true for animal sources of protein like red meat or pork.
The act of chewing on its own takes time and energy, and this creates more time for your body to smell and taste the food, which leads to higher satiety.
Once the food is in your stomach, it also takes longer to digest than a liquid protein shake, so whole foods can keep you feeling full for longer.
Whole foods are also more likely to include dietary fiber and water content so they take up more room in your stomach. This higher volume of food adds to feelings of fullness.
- Related Article: How To Increase Your Protein Intake Without Protein Powder
Frequently Asked Questions
Can You Just Drink Protein Shakes And Not Eat?
Yes, technically you can survive on protein shakes alone, but I do not recommend that you do this because you run the risk of nutrient deficiencies, digestive problems, lower mood and boredom. Aim to get no more than ⅓ of your total daily protein intake from protein shakes/supplements.
Do Protein Shakes Make You More Hungry?
Yes, for some people, protein shakes can make them more hungry because drinking liquid calories is often less filling than chewing solid food. Also, if the protein shake is high in sugar because it has added fruit, juice or honey, those quick-digesting carbs can actually increase cravings for even more food.
Should You Drink A Protein Shake If You Feel Full?
Whether you should drink a protein shake if you already feel full will depend on your goals. If you are trying to gain weight, you should drink the shake to get more calories & protein regardless. But, if you are trying to lose weight, you might want to wait until you actually feel hungry before drinking the shake.
If it’s the end of the day and you haven’t yet hit your protein target for the day, it is a good idea to drink a protein shake to meet your protein goal, even if you feel full. This will help you replenish your muscle protein overnight while you are sleeping. It’s important to maintain as much muscle mass as possible while losing weight, to keep your metabolism high.
About The Author
Lauren Graham is a Precision Nutrition Level 1 certified nutrition coach. She focuses on helping busy professionals balance healthy eating and purposeful movement. Lauren has a background in competitive swimming and is currently competing as a CrossFit athlete. She has a passion for training, teaching, and writing.