The Comprehensive Guide to Whey Protein: Everything You Need to Know - Perfect Keto

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The Comprehensive Guide to Whey Protein: Everything You Need to Know


Whey protein powder is one of the most studied nutritional supplements on the planet. Still, many people on low carb, keto, and Paleo diets have questions. Is whey good for you? Do you really need to take whey protein? What about dairy — isn’t dairy bad for some people?

In short, whey protein is good for you. And there’s a ton of science to back up that claim. The benefits of whey, in fact, extend well beyond muscle gain and into the realm of weight loss, healthy aging, and even disease risk mitigation.

But there’s much more to say on this topic. In this comprehensive guide to whey protein, you’ll learn:


How Whey Is Made

Most whey protein, you’re probably aware, comes from cow’s milk. And milk contains two primary proteins: casein (the solid) and whey (the liquid).

Casein protein: Casein accounts for 80% of extracted milk protein[*]. Along with whey, casein is also sold as a protein supplement, but it has two huge drawbacks:

  • Many people suffer from casein intolerance, which can manifest as digestive issues like stomach pain and gas[*]
  • Casein is less effective than whey for promoting metabolic health in overweight people[*]

Whey Protein: Whey protein accounts for 20% of extracted milk protein. It’s extracted and spray dried into powders that vary in protein concentration[*]:Whey protein powder — WPP is used in food products, and is about 12% protein, 70% lactose, and 1% milk fat

  • Whey protein concentrate — WPC is sold as a supplement, and ranges from 25-89% protein, 10-55% lactose, and 2-10% milk fat
  • Whey protein isolate — WPI is the purest form of whey protein supplement. It’s over 90% protein and less than 1% lactose and milk fat

WPI not only contains the most protein of the three, but also the least lactose, a milk sugar that causes digestive upset in about 65% of the world’s population[*]. Most whey isolate only contains trace amounts of lactose, which shouldn’t be a problem for most people.

Whey Protein Hydrolyzation

After whey is separated from casein, spray dried, and filtered, it’s possible that it goes through another step called hydrolyzation.

Hydrolyzation is when the protein is or broken apart for (purportedly) easier digestion. The resulting whey protein hydrolysate may enhance exercise recovery better than other forms of whey, though the cost of whey hydrolysate is generally higher[*].

Whey protein isolate is the type you’ll be reading about today. And WPI is, objectively speaking, a very high-quality protein.

How To Choose The Best Protein Powder

There are a couple of really accurate ways to rank your protein powder, and it’s not just by taste.

Browse our curated collection of fan-favorites and discover your new favorite snack or supplement.

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The best protein is going to be easy to digest and easy for your body to use.

The Food & Agriculture Organization and World Health Organization (FAO and WHO) have created a set of protein quality standards. These standards include[*]:

  1. Protein Efficiency Ratio: measures how much an animal grows when fed a given amount of protein — and any protein that scores about 2.7 is considered a very good protein efficiency.
  2. Biological Value: measures how well your body uses a protein in terms of protein absorbed vs. protein utilized in tissues. Foods high in amino acids, like meats and whey, tend to have high biological values.
  3. Protein Digestibility: measures how many amino acids you’re actually digesting when you eat a given protein. The maximum score is 1.0.

For all of these measures, a higher score is better. Here’s a quick table (values from the Journal of Sports Science & Medicine) reporting the scores of common proteins[*]:

values from the journal of sports science and medicine


   Protein Efficiency Ratio   Biological Value  Protein Digestibility
                Whey                     3.2             104                  1.0
                Casein                     2.5              77                  1.0
                Egg                     3.9             100                  1.0
                Beef                     2.9              80                  0.92
                Gluten                     0.8              64                  0.25

A couple of quick notes on this chart. Except for protein efficiency (in which whey is second only to egg) — whey is number one in every category.

Casein and beef? Both are decent but have much lower biological values and protein efficiency ratios than egg and whey. While gluten comes in at dismal digestibility and nutrient availability rates. No wonder so many people have issues with gluten.

So yes, whey tops the chart. And of all the factors contributing to whey’s scores, the amino acid composition may be the most important.

Amino Acids In Whey

Every protein molecule — from the ones in your protein powder to the ones in your steak — is made of amino acids. Think of amino acids as the building blocks of life. For instance, amino acids make up every organ and tissue in your body.

There are two types of amino acids: essential amino acids and non-essential amino acids.

You must get essential amino acids through food and supplementation, while your body can technically synthesize non-essential aminos on its own.

If a protein contains all nine essential amino acids — leucine, isoleucine, valine, methionine, tryptophan, threonine, lysine, histidine, and phenylalanine (say that ten times fast) — that protein is considered a complete protein. Whey is a complete protein.

A few of those essential amino acids are called branched-chain amino acids (BCAAs), which consist of leucine, isoleucine, and valine.

BCAAs are crucial for muscle protein synthesis and help you stay lean while losing weight. Whey contains these BCAAs in the highest concentrations of any protein and is especially high in leucine, the key amino for muscle growth and maintenance[*].

Whey is also packed with non-essential aminos like cysteine. Cysteine is a precursor to glutathione, your body’s main antioxidant. More on glutathione in a bit.

Along with amino acids, whey contains a bunch of bioactive compounds shown to have remarkable health benefits. You’ll learn these benefits soon. But first, you’ll want to learn how whey can help you stay strong and lean.

Whey For Staying Strong And Lean

It’s likely you’ve heard of whey in the context of exercise enhancement — and although this stereotype doesn’t tell the full story of whey’s benefits, there’s still plenty of truth to it.

Whey’s amino acid profile — BCAAs in particular — are largely responsible for muscle growth. BCAAs promote muscle synthesis and recovery because they help you maintain a positive net protein balance. What’s that mean? Just that muscle growth beats out muscle breakdown.

Maybe you don’t want big muscles. Maybe you want to stay lean and lose weight. Whey helps with that, too.

Lean muscle mass actually helps you lose body fat because muscle tissue is more metabolically active (burns more calories) than fat mass. Lean muscle mass also protects your body from disease as you age[*].

And adding lean muscle to your frame is simple. It involved resistance training and getting adequate protein. Here’s some of the evidence.

The Science Behind Whey and Muscle Synthesis

Whey Vs. Soy For Lean Mass[*] Scientists split people into three groups — whey protein, soy protein, and carbohydrate. Each group took their respective supplement (about 1.4 g protein/ kg body mass) over a span of nine months, along with resistance training.

At the end of the trial, the whey group had significantly more lean mass than the other groups. This was most likely due to the high leucine content of whey. Compared to the other groups, whey-fed subjects had 20% higher fasting serum leucine and 100% higher post-workout serum leucine.

So are these strength benefits entirely due to the aminos in whey? Maybe not.

Whey Vs. Aminos For Muscle Synthesis[*] Researchers forced rats to swim for two hours, then gave the exhausted rodents either hydrolyzed whey, an amino acid supplement, or a carb supplement. As expected, the rats who got whey and the amino acid supplement had way higher muscle synthesis than the rats who got carbs.

But only the whey-fed rats got a bump in mTor signaling. MTor, or mammalian target of rapamycin, is muscle growth-signaling pathway found not only in rat cells, but also in human cells. It’s complicated, but to oversimplify: more mTor equates to more muscle growth.

The takeaway? When it comes to muscle growth, whey is more than just a bunch of amino acids.

And whey doesn’t just help you get bigger and leaner at the gym. It also prevents muscle loss as you age.

Whey Prevents Age-Related Muscle Loss[*] Researchers had 70 older women consume either whey protein or placebo (both pre- and post-workout) over the course of a 12-week strength training program. What happened? The women who consumed whey had significantly more muscle strength and lean mass compared to the women who drank the placebo. Regardless of timing.

Whey protein supplementation, as this last study showed, can help mitigate a nasty age-related muscle-wasting condition called sarcopenia. This gradual loss of muscle increases disease risk and decreases quality of life[*]. The good news? Combining whey with strength training can help.

Now on to a related benefit: whey supplementation for fat loss.

Whey To Support Weight Loss On Keto

The ketogenic diet is one of the best out there to support fat loss.

If you’re not familiar, keto is a high-fat, low-carb diet that gets you burning fat instead of glucose from carbs for energy. This is called fat adaptation. And when you become fat adapted, you actually burn (or oxidize) your own adipose tissue for energy[*].

But keto isn’t just about eating healthy fats like MCT oil and nut butter. You need healthy protein too. That protein helps you maintain lean muscle while you’re losing weight.

That’s where whey comes in. Whey protein helps you maintain lean muscle mass while losing weight on keto. Some examples now.

The Science Behind Whey and Fat Loss

In one study, 25 healthy people were put on two diets: calorie restricted and ketogenic. Only the keto group, however, supplemented whey protein. Results? Both groups lost weight, but the whey-supplemented keto group maintained muscle much better[*].

In another study, 188 obese people were kept in ketosis (via carb and calorie restriction), and given a whey protein drip for 10 days. What happened? They lost body fat, but not muscle mass[*].

And so whey protein, combined with a ketogenic diet, helps you lose fat instead of muscle.

Okay, a change of pace now — a review of the special compounds that really give whey an edge over other protein powders.

Bioactive Compounds In Whey

Yes, whey is packed with BCAAs. And yes, BCAAs are crucial for muscle growth, recovery, and body composition. But when it comes to the benefits of whey, BCAAs are less than half the picture.

That’s right. Along with leucine, isoleucine, and valine — whey contains a number of compounds that have unique health benefits. Here’s a partial list:

  • Alpha-lactalbumin: shown to enhance immunity and cognitive health[*]
  • Beta-lactoglobulin: shown to mitigate allergies and boost immune health[*]
  • Lactoferrin: promotes healthy bones, healthy iron levels, and healthy immunity[*][*]
  • Immunoglobulins (IGG, IGA) — support the immune response to infection[*]
  • Lysozyme — a potent anti-bacterial enzyme[*]
  • Lactoperoxidase — another enzyme with anti-bacterial properties[*]
  • Cysteine: an amino acid that enhances your body’s antioxidant response

The Benefits of Cysteine

Each of these compounds has remarkable health effects, but cysteine may trump them all. Cysteine, if you recall, is a non-essential amino acid and a cofactor of glutathione.

Glutathione is your body’s master antioxidant and its duties include:[*][*][*]

  • Protecting your body from oxidative stress and free radical damage
  • Supports your mitochondria — the energy-making powerhouses of each and every cell in your body
  • Boost your immune system
  • Reduces inflammation
  • Makes other antioxidants like vitamin C more powerful
  • It’s a cofactor for several detox enzymes, making glutathione important for cellular detox

So you can see why it’s important to support glutathione production, especially when you’re sick or stressed. Consuming high-cysteine foods can help.

Whey contains plenty of cysteine. Therefore, whey helps combat oxidative stress and disease.

Whey Improves Chronic Disease

Whey supplementation may help prevent many chronic diseases.

Non-alcoholic fatty liver disease (NAFLD), or the accumulation of visceral fat in the liver, is a growing problem — now affecting 30% to 40% of U.S. adults. This condition not only raises your risk of liver cancer, but appears to increase heart disease risk too.

NAFLD is also associated with metabolic disorders like obesity and type 2 diabetes[*].

Fortunately, researchers are making progress in NAFLD-related clinical trials. For instance: when 38 people with liver disease were given whey for 12 weeks, they emerged with significantly better liver health. Researchers give cysteine credit for this effect. Their logic looks something like this[*]:

  • Whey contains cysteine
  • Cysteine boosts glutathione levels
  • Glutathione reduces oxidative stress (ROS) — which strains the liver
  • Liver function improves

Along with NAFLD, certain carcinogenic tumors have been reported to shrink during whey supplementation[*]. And lactoferrin, another compound found in whey, appears to have anti-cancer effects on human colorectal polyps[*].

In addition to liver disease and cancer, whey protein supplementation may help with:

  • Obesity and Type 2 Diabetes — via improved insulin sensitivity[*]
  • Cardiovascular disease — via lower blood pressure and better vascular function[*]
  • Crohn’s Disease — via healthier gut tissues — less intestinal permeability (leaky gut)[*]
  • Immune Diseases — whey appears to downregulate autoimmunity and upregulate healthy immune function[*]

So clearly, whey is more than just protein. For most people, in fact, whey is a safe supplement with a spectrum of positive effects.

For most people, yes. But not for all.

Side Effects And Dangers Of Whey

Quick disclaimer: nothing in this article should be taken as medical advice. See your doctor for that. That said, here are a few reasons to avoid whey protein:

  • You have a dairy allergy. If you have a dairy allergy, you shouldn’t consume anything made from milk. Yes, that includes whey protein. Alpha-lactalbumin and beta-lactoglobulin are common dairy allergens, and you should avoid them at all costs if you have a dairy allergy[*].
  • You’re highly sensitive to dairy. A dairy intolerance or dairy sensitivity is not as dangerous as a dairy allergy.

Sensitivities and intolerances usually present as gastrointestinal distress — stomach pain, cramping, gas, and diarrhea to name a few symptoms. If you’re dairy intolerant, whey isolate powder — which contains only trace amounts of lactose — is your best bet[*].

But that’s not a guarantee. Whey isolate is well-tolerated by most, but not everyone. In other words, you’ll have to experiment with whey for yourself.

  • You have kidney or liver damage. High protein intake is dangerous if you have existing liver or kidney disease or damage. There’s little evidence, however, to suggest that whey (or any form of protein) causes organ damage in healthy people[*].

By now you’re probably wondering about optimal dosage and timing of whey supplementation. We’ve got you covered.

How Much Whey Protein Should You Take?

How much protein do you need? That depends on your goals.

If you attend multiple spin classes a week, you’ll need more protein to support your recovery and muscle synthesis. Not into heavy exercise? You need less. Here are research-backed recommendations for daily protein intakes at different activity levels[*]:

  1. Intense exercise — 1.6 grams protein per kilogram body weight (around 150 grams protein for a 200 lb person and 100 grams protein for a 140-pound person)
  2. Moderate exercise — 1.3 grams protein per kilogram body weight (around 120 grams protein for a 200 lb person and 80 grams protein for a 140-pound person)
  3. Minimal exercise — 1 gram protein per kilogram body weight (around 90 grams protein for a 200 lb person and 60 grams protein for a 140-pound person)

By the way, long-term consumption of up to 2 grams protein per kilogram body weight per day is considered “safe” — with 3.5 grams as the tolerable upper limit[*].

But wait, doesn’t a high protein intake kick you out of ketogenesis? It depends. But when it comes to maintaining lean mass and losing weight: high protein keto diets work for most people. A published example now.

Seventeen obese people were put on two types of diets[*]:

  1. High-protein (30% of calories), low carb ketogenic diet
  2. High protein, moderate carb non-ketogenic diet

Results? The high protein keto folks lost more weight and experienced less hunger than the moderate protein folks.

So if your goal is weight loss, you don’t need to limit protein on keto.

As an aside: if you like calculating exact macronutrient ratios, check out the Perfect Keto Calculator. It’s a handy dandy tool.

When Is The Best Time To Take Whey?

What about timing? Does it matter?

Yes. You can eat protein any time of day, but you really want to eat protein in the morning. Why? Because protein — specifically, the amino acid tryptophan — is necessary for serotonin production. And serotonin, you’ve probably heard, is your happy neurotransmitter.

Having serotonin around in the morning — in addition to supporting your mood — also supports your sleep. That’s because serotonin is a precursor to melatonin, your sleep hormone.

Tying it all together: a high protein breakfast has been shown, in a controlled trial, to improve both sleep and salivary melatonin in Japanese students[*]. Pretty cool.

What about pre- and post-workout protein timing? Don’t stress on this one. Recall, if you will, the study on older women supplementing whey[*]. Both the pre- and post-workout groups showed similar lean mass gains.

Rule of thumb? Provided you have amino acids in your blood after exercise, it doesn’t matter when you eat that protein shake.

Should You Try Whey Protein?

If you’re still reading, congratulations: you’re now an expert on whey protein. To keep things fresh, here’s a quick recap of what you learned today:

  • Whey protein is made from dairy, but most whey supplements contain very low amounts of lactose and no casein
  • Whey isolate is the purest form of whey
  • In terms of protein digestibility and absorption, whey is the best bang for your buck
  • Whey is packed with amino acids, especially BCAAs — which help you stay lean and burn fat
  • Whey protein helps you maintain lean mass during weight loss (and as you age)
  • Cysteine, found in whey, supports glutathione production — which may help prevent chronic disease
  • Whey also promotes heart health, immunity, and gut function
  • If you have a dairy allergy, please avoid whey; try a high-quality beef protein isolate or veggie protein instead
  • If you are lactose intolerant, you may still be able to handle whey protein isolate
  • You don’t need to limit protein on a keto diet
  • Your daily protein requirement depends on your activity level, age, and health goals — and it doesn’t matter if you supplement before or after a workout

Verdict? Whey protein is a highly bioavailable, versatile protein source that you should probably add to your daily routine.

READ NEXT: Keto Bodybuilding: Can You Gain Muscle Without Carbs?


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