Can You Mix Whey Protein With Soy Milk? (Follow These Tips)

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Many of my nutrition clients have asked me about mixing whey protein with soy milk and whether I recommend that option so I decided to answer that in more detail. 

Can you mix whey protein with soy milk?  Yes, you can mix whey protein with soy milk. Unsweetened soy milk adds extra protein and fat, keeping you full for longer and making it easier to meet your protein needs. To keep your soy protein intake within the recommended amount, keep your consumption to 2 cups per day; less if you are eating other sources of soy. 

With that said, before you start mixing whey protein with soy milk, you should know the pros and cons, and how to do it properly for optimal results.

In this article, I’ll also explain: 

  • When to consume whey protein and soy milk
  • Who should and shouldn’t mix whey protein and soy milk
  • The best type of protein powder to mix with soy milk

This article is part of our series on What Can You Mix With Whey Protein (13 Examples)

Benefits of Mixing Whey Protein With Soy Milk

Pros vs Cons of mixing whey protein with soy milk

The benefits of mixing whey protein with soy milk are:

  • It can help you hit your daily protein goal
  • It’s a lower-calorie alternative to milk
  • It creates a lactose-free protein shake

1. It Can Help You Hit Your Daily Protein Goal

Soy milk has 8g of protein per cup helping to boost the protein in your shake making it easier to hit your daily protein goal. 

Whenever my clients come to me struggling to eat enough protein, my first recommendation is always to try increasing the amount of protein they are eating at each meal before we add in any additional servings. A great way to do this is to swap a higher protein item. 

Soy milk has 8g of protein per cup, which is quite high compared to other milk alternatives like coconut or almond that typically have 1-2g. By swapping your liquid in your protein shake to soy milk, you can help to increase your protein intake making it much easier to hit your daily protein goal. 

2. It’s a Lower-Calorie Alternative to Milk

Soy milk has fewer calories than regular milk, making it a better choice for those looking to lose body fat. 

Per cup, unsweetened soy milk has 75 calories compared to the 122 calories in 2% milk. If you’ve tried to lose body fat before, you know that saving yourself almost 50 calories can be extremely beneficial. Especially if you are consuming multiple protein shakes per day. 

It’s also important to remember these calories are also from a drink, which is much less likely to fill you up compared to 50 calories worth of food. Choosing soy milk to mix with whey protein will make it easier to eat fewer calories in a day than you are burning, leading to successful weight loss. 

I recommend opting for unsweetened soy milk as it has fewer calories and sugar compared to the sweetened version.  If your protein shake is flavored (as many are), then there’s no need to also have sweetened soy milk.

3. It Creates a Lactose-Free Protein Shake

Soy milk is lactose-free, which is important for those that experience digestive issues when eating lactose. 

Experts estimate that approximately 68% of the population is lactose intolerant. This means that they experience some sort of digestive discomfort, such as bloating, gas, diarrhea, etc. after consuming a food that contains lactose, such as milk. 

If you are drinking protein shakes daily, especially more than once per day, regular digestive discomfort can interfere with your day to day life. I don’t know about you, but I have trouble completing activities, especially ones like going to the gym, when my stomach is bothering me.

Digestive upset is also likely to start to interfere with your nutrition. Each person is a little bit different with their tolerance to eating when they have digestive issues, but it will eventually start to get in the way of consuming a balanced diet. 

Drawbacks of Mixing Whey Protein with Soy Milk

The drawbacks of mixing whey protein with soy milk are:

Soy milk contains soy protein and isoflavones which have a recommended daily limit, therefore it’s important to consider the total amount of soy you’re consuming in a day before mixing your whey protein with soy milk. 

Research recommends that daily, soy protein intake and isoflavone intakes are between 15-20g/ day and 50-90 mg/ day, respectively. Isoflavones are a type of plant estrogen that is similar in function to human estrogen, and therefore can bind to our own estrogen receptors leading to changes in our hormone levels that can be negative in specific cases.

Per cup of soy milk, you are consuming 7g of soy protein and approximately 20mg of isoflavone (although this will vary based on the brand). 

This is important to remember if you are consuming multiple protein shakes per day as the amount of soy protein and isoflavones will quickly exceed the recommended limit. 

You also should be considering what other sources of soy you may be consuming that would additionally add to this intake. Common sources of soy include vegan protein powders, vegan meat alternatives, tofu, and edamame. 

How Much Whey Protein Should You Add to Soy Milk?

I recommend using a ratio of 1 scoop of whey protein to 8oz of soy milk. This will create the best taste and texture but you can customize it based on your preference.  Any more may lead to clumping.  

If you like a sweeter shake you can reduce the amount of soy milk to 6oz and if you like a diluted shake, increase the soy milk to 10oz.

Soy Milk & Protein Powder: When To Consume?

Soy Milk and Protein Powder

Is Whey Protein & Soy Milk Good for Pre Workout?

Whey protein and soy milk are a good option before a workout to provide an easily digestible protein source with some carbohydrates. I recommend choosing a sweetened option to add additional sugar that will provide energy during your workout.

While soy milk does have some carbohydrates, you’re likely to find it’s not enough to get you through your whole workout. For the most energy, I recommend having a carb-dense meal, like oatmeal, 1-1.5 hours before your workout than having your whey protein and soy milk 30-45 minutes before your session. 

Since soy milk has some fat and protein it’s best to limit your consumption to 1 cup or less so you have the most energy for your workout.

Is Whey Protein & Soy Milk Good for Post Workout?

Whey protein and soy milk are great post-workout as it provides a quick digesting protein source as well as some carbs, which is beneficial for muscle recovery and growth. 

While soy milk provides some carbs, it’s not a replacement for a full post-workout meal. It’s a great option to consume on the way home from the gym as the carbs are sufficient enough to start the process of muscle repair and recovery.

It’s best to stick with sweetened soy milk if consuming after your workout as it has more carbs in it from the additional sugar. 

Is Whey Protein & Soy Milk Good for Breakfast?

Whey protein and soy milk are good for breakfast as the additional fat and protein from the soy milk will help keep you full longer. 

If you are a habitual mid-morning snacker, I can almost guarantee it’s because you are eating a carb-heavy breakfast. Carbs are a quick source of fuel for our body, meaning you will have a ton of energy right after eating but you are likely to find yourself hungry within a couple of hours. 

If you can instead add protein and fat into your breakfast, you will feel full for longer after you eat and skip that high-calorie mid-morning snack. Soy milk and whey are high in protein with some fats from soy milk. If you can pair this with a carb source, such as oats or cereal, you will have a satisfying and filling breakfast option.

Is Whey Protein & Soy Milk Good for Before Bed?

Whey protein and soy milk are a good option before bed if you are having trouble consuming enough calories during the day or you’re looking for a sweet treat. 

If you are having trouble eating all your calories during the day because you don’t have an appetite, I usually recommend trying to add a protein shake to your day. This will add more calories without being overly filling. Soy milk and whey is a great option for this as soy milk is higher in calories compared to water.

It can also make for an evening sweet treat that is much lower in calories compared to other dessert options. 

Who Should Mix Whey Protein With Soy Milk?

Mixing whey protein with soy milk is a great option for anyone looking to maintain or lose weight as it’s lower in calories compared to regular milk. 

You may be wondering why I’m recommending soy milk and not water if a lower calorie is the goal. Yes, opting for lower-calorie choices will help overall but we also want to balance that with what will fill you up and leave you feeling satisfied.

Soy milk will add additional protein and fat to your protein shake, which is helpful when trying to lose body fat as it will keep you full for longer after you eat. It will also give your shake a better taste and texture leaving you more satisfied after you eat.

Overall, the 72 calories in soy milk are likely worth it to make a more filling and more enjoyable protein shake. This may only not be the case for someone in an extreme situation, such as a bodybuilder very close to competition day.

Make sure you stick to unsweetened soy milk to avoid any unnecessary sugar and calories. 

Who SHOULD NOT Mix Whey Protein With Soy Milk?

Mixing whey protein with soy milk may not be the best option for those in a bulking phase and struggling to eat enough as there are liquids that can provide more calories than soy milk. 

If you have ever struggled to eat enough in a bulking phase you know the importance of liquid calories. Liquid calories are the least filling and therefore very important to help boost your daily intake without impacting your appetite. 

While soy milk has some calories, there are other liquids to mix whey with that will provide more of a bang for your buck, such as chocolate milk or whole milk.

It’s also important to remember that we don’t want to be consuming too much soy in a day. If you are consuming multiple protein shakes in a day, as well as other sources of soy like tofu or edamame, soy milk may also not be the best option for you. 

This is likely the case if you are vegetarian or vegan as many plant-based protein sources are soy-based. Another milk alternative, such as almond or coconut may be a better choice.

Best Types of Protein to Mix With Soy Milk

Best types of protein to mix with soy milk

Around a workout, it’s best to mix a whey isolate with soy milk for quick digestion. For this, my recommendation is Legion Whey+

Legion Whey+

For other times during the day, Legion Casein+ is my recommendation as it’s slower digesting and will keep you full for longer after consuming.

Legion Casein+ Protein Powder

I typically recommend mixing soy milk with a dairy-based protein powder as most vegan protein powders contain soy protein.  It’s important to ensure our soy consumption is within the recommended daily intake so sticking to one source of soy is best. 

You may be wondering, what if I’m vegan or don’t consume dairy? In that case, I recommend a vegan protein powder that is pea protein-based like Vega Sport Vegan protein powder.

If you are looking for more affordable protein options, Myprotein Impact Whey Isolate and Bodybuilding Signature Casein Protein are both great choices. 

Whey Protein & Soy Milk Shake Recipe: Chocolate Mocha Protein Shake

whey protein and soy milk shake recipe - chocolate mocha protein shake

This chocolate mocha protein shake is the perfect pre or post-workout meal, with plenty of carbs and protein for optimal performance and recovery. The instant coffee will also give a boost of caffeine which research shows can increase your muscle’s uptake of carbohydrates helping improve your workout and recovery.


  • 125g frozen banana
  • 1 scoop chocolate whey protein powder
  • 1 cup unsweetened soy milk
  • 1 tbsp cocoa powder
  • 2 tbsp oats
  • 1 tbsp instant coffee


  1. Place all ingredients into a blender and blend until smooth. The shake will be quite thick so you likely will need to scrape down the sides a few times when blending.  

Frequently Asked Questions

Is It Safe To Add Whey Protein With Soy Milk?

Yes, it is safe to add whey protein with soy milk. The soy milk will add 8g of protein to your shake. Soy milk does have some fat, therefore I recommend limiting your soy milk to 1 cup around a workout. This will ensure you maintain the rapid absorption benefits that you are looking for when you consume whey.

What Else Can You Mix Whey Protein With?

About The Author

Laura Semotiuk

Laura Semotiuk is a Precision Nutrition Level 1 certified nutrition coach. She works with athletes and active individuals looking to improve performance and develop healthy nutritional habits and behaviors. She has a passion for cooking, meal prepping, and creating simple and healthy recipes.

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