Soy vs. Whey Protein: Which Protein Fits Your Health Goals?

Written by: Jennifer Chesak, MSJ
Medically reviewed by: Ecler Ercole Jaqua, MD, MBA, DABOM

Got protein? That’s the big question on the internet these days, and with good reason. Protein supports muscle mass, metabolic health, and overall body function. If you’re looking to boost your intake beyond what you get from meals and snacks, wading through all of the protein supplement options can feel overwhelming. Here’s what to know about pea, soy, and whey protein powders.

I love a good protein powder. I try to get as much of my protein as possible from my meals and snacks. But I’m a vegetarian, so I often fall short.

To be clear: You can get enough protein from meals alone even on a vegetarian or vegan diet, but doing so typically involves more planning or consuming a higher volume of food. The last thing I want to do before my afternoon run is have a giant lunch that will slosh around while I log my miles. So I stick to a light meal and a protein powder mixed in soymilk.

Protein powder is a great choice for adding more protein beyond what you’re getting from meals. Protein smoothies or shakes are also super convenient, whether on the go or when you just need sustenance—stat.

For example, after an afternoon weightlifting workout, I like to consume about 30 grams of protein to help preserve and build muscle. Protein powder mixed in the liquid of my choice is the easiest way for me to do that without destroying my appetite for a nutritious dinner. It also satisfies any hunger leading up to dinner and helps ensure I meet my protein goals for the day.

Whatever your reasons for researching protein powder, you might be overwhelmed with the choices available to you. Should you choose whey, soy, pea, or another type? In this article, we explore the differences between various types of protein and how to pick one that’s right for you.

Soy vs. Whey Protein: The Key Differences

Soy protein comes from soybeans. It’s a complete protein, meaning it contains all nine essential amino acids. Essential amino acids are the ones your body can’t produce on its own and must get from foods or supplements.

What’s the difference between soy protein and soy protein isolate? Soy protein isolate is a highly refined version of soy protein. The refining process removes the fats and carbohydrates. Soy protein isolate contains 90% protein.

Whey protein comes from cow’s milk. It is a byproduct of cheese-making. Cheesemakers add enzymes to milk to create curds. Whey is the leftover liquid that can be dried into a powder. Whey is also a complete protein.

What’s the difference between whey protein and whey protein isolate? Whey protein isolate is a highly refined version of whey. The refining process removes much of the lactose and fat content. Whey protein isolate contains 90% protein.

Which should you choose—soy or whey? The answer depends on your health goals, dietary preferences or intolerances, and more.

If you’re lactose intolerant or have a dairy allergy, for example, avoid whey. However, whey protein isolate’s much lower lactose content means it could be an option for those with lactose intolerance. Whey is off the table if you eat a vegan diet. And some people have sensitivities or allergies to soy and may need to avoid soy products.

One potential plus for soy: It contains soy isoflavones. Soy isoflavones are phytoestrogens, plant compounds that weakly mimic the hormone estrogen and bind to estrogen receptors in your body. But phytoestrogens are not actually estrogen.

This estrogen-mimicking effect may be helpful if you are undergoing the menopause transition (aka perimenopause) or are postmenopausal. Specifically, soy isoflavones may help alleviate some menopausal symptoms, including hot flashes. They also help reduce total cholesterol and low-density lipoprotein (LDL) cholesterol, sometimes called “bad” cholesterol.

Research also shows that the consumption of soy isoflavones is not linked to breast cancer and may even help reduce risk or risk of reoccurrence. Although research has not shown direct evidence of harmful effects of soy isoflavones, consulting your doctor is always a good idea before starting a new supplement, especially if you have underlying health conditions or take medications.

Pea Protein vs. Whey Protein

Pea protein is made from yellow split peas and contains all nine essential amino acids. However, it contains only a small amount of methionine, an amino acid necessary for muscle protein synthesis. Muscle protein synthesis is the process of building and repairing muscle. Because of its lower methionine content, pea protein is sometimes called a “near-complete” protein.

Compared with whey, pea protein is also lower in leucine, the most crucial amino acid for muscle protein synthesis.

Many pea protein powder manufacturers include other plant proteins that help boost the powder’s amino acid profile. Options include hemp, quinoa, pumpkin, and brown rice protein.

Whey, on the other hand, contains high levels of all the essential amino acids and does not need to be mixed with additional protein types. However, as noted above, whey isn’t suitable for those with a dairy allergy or lactose intolerance. So if you have either of these, pea protein is a great option.

"Pea protein is naturally hypoallergenic and well tolerated for most people, including those with sensitivities or allergies," says Alexander Leritz, RD, a sports nutritionist with JM Nutrition.

The following table shows a head-to-head comparison of pea, soy, and whey protein.

Pea protein vs. whey protein vs. soy protein

Amino Acids, Leucine, and Muscle Support

Now let’s dig into the nitty-gritty regarding amino acids. Your body needs 20 amino acids to perform its functions. Nine of the amino acids it needs are essential. This means that the body cannot make them, so you need to get them through diet or supplements.

While all nine essential amino acids are necessary, leucine plays a central role in triggering muscle protein synthesis.

9 essential amino acids and their functions

Whey or Soy Protein for Weight Loss

Neither whey nor soy protein is the clear winner for weight management, but upping your protein intake may help with weight loss.

Researchers compared a soy protein supplement, a whey protein supplement, and a placebo (inactive supplement) in a clinical trial. The final analysis included 35 participants with obesity. Participants were randomly assigned to the groups and didn’t know which supplement they were taking (daily for 12 weeks). The overall results showed no significant changes in weight. While protein supplements alone may not directly cause weight loss, they can support behaviors that promote it.

However, they did find that those in the soy protein group ate fewer calories, less protein, and less fat overall. The study authors note that a longer study might have shown a greater effect on weight.

Can protein help you lose weight? 

Yes, protein might help you manage weight. “For those pursuing weight loss goals,” says Kate Lyman, MPH, “a protein supplement can be helpful in promoting satiety and ensuring one is consuming enough protein to maintain muscle and bone mass as they lose body weight.” Here are more details on how protein aids weight management.

• Boosts satiety. Protein helps slow gastric emptying (how fast food moves from your stomach to your small intestine). This also helps slow the absorption of food into your bloodstream, which helps you feel fuller from your meals and satisfied for longer.

• Helps suppress your appetite. Protein stimulates the release of glucagon-like peptide-1 (GLP-1), a hormone that helps regulate appetite and blood sugar. Protein also reduces ghrelin levels, a hormone that tells your brain you’re hungry.

• Promotes body recomposition. If you strength train, your body has increased protein needs for building and repairing muscle. Strength training revs your metabolism and helps you burn fat while growing muscle. Over time, your body gets leaner. This is called body recomposition. Sometimes recomposition leads to weight loss; other times, weight may stay the same while measurements decrease because muscle tissue takes up less space than fat tissue.

• Supports your metabolism. When compared to the other macronutrients (carbohydrates and fats), protein requires your body to burn more calories during digestion. This is called the thermic effect of food (TEF).

Lyman adds one caveat when searching for a protein supplement to aid with weight loss. “It’s important to know the difference between a protein supplement, which contains mostly just protein, versus a meal replacement shake, which also has additional carbs and fat and is meant to replace a full meal,” she says.

You might be looking for a meal replacement option. But if you’re just trying to supplement your overall protein intake then opt for a protein powder that doesn’t have an extensive ingredient list or a high carbohydrate or fat profile.

How much protein do you need?

Your protein needs will depend on your physical activity level and other factors.

But a good rule of thumb for active individuals is to aim for about 0.65 to 1 gram of protein per pound of body weight per day. So if you weigh about 150 pounds, that’s about 98 to 150 grams. For sedentary adults, a lower intake may be sufficient.

Aim for the higher end if you are highly active and especially if you strength train. And spread your protein intake throughout the day.

How to Choose the Best Protein Powder for Your Goals

Now that you have all the details on the power of protein, you might be wondering how to choose the best one (whey, soy, or pea) for your goals. Of course, you don’t need to stick to just one type. I’m a fan of several and mix them into my routine.

Step 1: Do you have any dietary restrictions or preferences?

The first step is to figure which type is best for you based on any allergies, intolerances, or sensitivities. If you don’t have any of these, then you can skip to the next step.

Whey is a dairy-based animal product, so it’s not suitable for vegans or those with dairy allergies. It also contains lactose, so it’s not suitable if you’re lactose intolerant. Some people also have a soy allergy and need to steer clear of soy protein.

Pea protein, on the other hand, is generally hypoallergenic for most people.

Step 2: When are you planning to consume your protein powder?

If you’re consuming protein to help you stay full and feel energized, pea protein digests more slowly than soy or whey, releasing into your bloodstream gradually. For this reason, pea protein is a great choice in a morning or lunchtime smoothie or in a shake between meals.

If you’re looking for faster digestion to support your muscles post-workout, whey will do the trick. However, timing is less crucial than older research has made it out to be. Consuming protein within an hour or so after exercise can aid recovery. But your total daily protein intake is more important than precise timing.

“At the end of the day,” Leritz says, “there is no single protein powder that is universally superior. More important is finding the right product for you; one that fits your nutrition needs, your tolerances, and your lifestyle.”

Step 3: Find a reputable product

With your answers for steps one and two ready, you can use the following questions to helpfind a high-quality protein powder to stock in your pantry.

Has the product undergone third-party testing?

Third-party testing means that an independent lab has verified that the product contains exactly what the label says and nothing it shouldn’t. Testing also evaluates a product for unsafe levels of impurities, such as pesticides, heavy metals, and more. Look for certifications such as NSF Certified, USP Verified, and ConsumerLab.com Approved.

Does the product have transparent labeling? 

You don’t want a product that hides behind vague terms like “proprietary blend.” A trustworthy product discloses every ingredient and its amount on the label.

Is the brand reputable?

GMP Certification indicates that the brand follows Good Manufacturing Practices to ensure quality. You can also search whether a brand has received any warning letters from the Food and Drug Administration for any marketing practice violations, such as making inappropriate medical claims that a supplement can cure a condition or disease. You can also scan Better Business Bureau and Trustpilot for independent ratings, reviews, or any potential red flags.

A Protein Powder Option from Veracity

Veracity recently launched its Metabolic Power Protein powder, which provides 20 grams of plant-based protein per serving. Most single-source plant proteins are missing one or more of the essential amino acids the body can’t produce on its own—pea protein, for instance, is naturally low in methionine, a gap that proteins from seeds like pumpkin can help fill.

Metabolic Power Protein is a complete protein made from a blend of all three (organic peas, pumpkin seeds, and chia seeds). Together they cover the full range of essential amino acids needed for muscle repair and recovery. It also includes added ingredients intended to support metabolic function like MyoVera, a patented combination of chromium (a trace mineral) and amylopectin (a polysaccharide). In one human clinical trial, when paired with adequate protein and exercise, chromium and amylopectin roughly doubled the rate of muscle protein synthesis when paired with adequate protein intake and exercise.

It’s free of added sugar and has a subtle vanilla-cinnamon flavor that works well in shakes, smoothies, and more. The cinnamon has the added benefit of helping to stabilize blood sugar.

All Veracity supplements are manufactured in the United States with third-party tested ingredients made in FDA-reviewed NSF- and GMP-certified facilities and tested for heavy metals.

Key Takeaways

• When considering a protein powder supplement, you have several options, including soy, pea, or whey.
• Which one is best for you will depend on your dietary restrictions and your health goals.
• Veracity offers reputable and third-party tested supplements, including a pea protein powder, formulated to support your metabolism and overall health.
  
  

Frequently Asked Questions (FAQs)

What is soy protein isolate?

Soy protein isolate is protein derived from soybeans. It is a highly refined version of soy protein. The refining process removes the fats and carbohydrates. Soy protein isolate contains 90% protein.

Is soy protein isolate bad for you?

No, soy protein isolate isn’t bad for you. However, it’s not a fit if you have a soy allergy or sensitivity. Soy protein contains soy isoflavones, which bind to estrogen receptors. Research shows no evidence of harm with soy isoflavones. In fact, research points to potential benefits, including lower cholesterol, reduced menopausal symptoms, and a lower breast cancer risk. As always, consult your doctor before starting a soy supplement or any new supplement.

What is the difference between whey protein and whey protein isolate?

Whey protein isolate is a highly refined version of whey protein. The refining process removes much of the lactose and fat content of whey. Whey protein isolate contains 90% protein.