Section 1
What whey protein is
Milk contains two proteins. About 80% is casein, the part that curdles into cheese. The other 20% is whey, the thin liquid that separates out when milk is curdled. For most of the history of cheesemaking it was fed to pigs or poured away. It turned out to be the most complete, most easily absorbed protein in the human diet.
Whey is a complete protein: it contains all nine essential amino acids, the ones your body cannot make and has to eat. It scores the maximum 1.0 on the PDCAAS scale, the standard measure of how well a protein is digested and used. It digests quickly, so amino acids reach the blood within an hour of drinking it. And it carries more leucine than any other common protein: leucine is the amino acid that switches muscle protein synthesis on, which is why whey is the protein sports scientists reach for first.
All nine essential amino acids
With the highest leucine content of any common protein, about 11 g per 100 g of protein.
Fast and fully absorbed
PDCAAS 1.0, the top score. Amino acids reach the bloodstream in under an hour.
Almost no lactose in an isolate
The filtration that makes an isolate removes nearly all the lactose, fat and cholesterol.
Section 2
How whey protein powder is made
Three steps, and the second one decides the quality of what ends up in the jar.
- Separate. Milk is curdled; the solids go to cheese and the liquid whey is collected. At this point it is about 6% solids, most of it lactose, with less than 1% protein.
- Filter. The liquid is passed through membranes to remove water, lactose, fat and minerals and concentrate the protein. Cross-flow microfiltration does this with ceramic membranes at low temperature and no chemicals, so the protein keeps its native shape. Ion exchange uses acid and alkaline chemistry, is cheaper, and strips out some of the minor protein fractions (lactoferrin, immunoglobulins) that are part of what makes whey worth eating.
- Dry. The concentrated liquid is spray-dried into powder. Cold-processed means the whey is kept below the temperature at which proteins denature throughout, so it dissolves cleanly and is absorbed the way it was in the milk.
How a whey is filtered is usually the one thing a label does not tell you. If it does not say cross-flow microfiltered, assume it is not.
Section 3
Concentrate, isolate or hydrolysate?
The amount of filtering decides which of the three you are buying.
Source: Hoffman & Falvo, Journal of Sports Science and Medicine 2004; 3(3): 118–130.
For most people the isolate is the right answer. You get 20 g of protein in a 90-calorie scoop instead of 130–150, almost no lactose, and a shake that tastes of the fruit you put in it rather than of milk. A concentrate is fine for baking. A hydrolysate is a medical product and costs accordingly.
Section 4
How whey compares with other proteins
Biological value and PDCAAS from Hoffman & Falvo (2004); leucine figures are typical values and vary by brand and processing.
Whey vs casein. Both come from milk and both are complete. Casein clots in the stomach and releases amino acids over several hours; whey passes straight through and peaks within the hour. That makes whey the better choice after exercise and at breakfast, and it is why studies comparing the two find whey produces a bigger rise in muscle protein synthesis in the hours after a dose. Casein has its place before bed.
Whey vs soy. Soy is the best of the plant proteins and also scores 1.0 on PDCAAS, but it is lower in leucine and in the sulfur amino acids methionine and cysteine, and in head-to-head trials whey has produced greater gains in lean mass and greater fat loss. A 2011 USDA study that gave adults a daily whey or soy supplement for six months, with no diet or exercise instructions, found the whey group finished about 2 kg lighter with a smaller waist and lower levels of the hunger hormone ghrelin (Baer et al., Journal of Nutrition 2011; 141: 1489–94).
Whey vs pea and other plant blends. Useful if you do not eat dairy. Expect to use 25–30% more powder to get the same usable protein, and check that the blend is complete.
Section 5
What whey protein actually does
Four things are well supported by the research. Everything beyond them is marketing.
Builds and repairs muscle
Combined with resistance training, whey increases lean mass and strength more than training alone. The mechanism is leucine: it signals muscle to start rebuilding, and whey delivers more of it, faster, than any other food.
Controls appetite
Protein is the most satiating macronutrient, and whey is the most satiating protein tested: it raises the fullness hormones CCK and GLP-1 and lowers ghrelin. In practice a whey breakfast means fewer calories eaten by lunch (Hall et al., British Journal of Nutrition 2003; 89: 239–48).
Steadier energy
A shake built on protein and a little fat digests slowly relative to a bagel or cereal, so blood sugar rises and falls gently. That is the difference between an even morning and a 10 a.m. slump.
Protects muscle as you age
Adults lose 3–8% of their muscle per decade after 30, faster after 60. Older adults need more protein per kilo than younger ones and absorb it less efficiently; whey, taken with resistance exercise, is the best-studied way to slow the loss (Bauer et al., PROT-AGE Study Group, 2013).
Section 6
Side effects, and who should not use it
Whey is a food. In healthy adults there is no evidence that normal intakes, up to about 2 g of protein per kilo of body weight a day from all sources, harm the kidneys, the liver or the bones. The practical problems are these:
- Milk allergy. Whey is a milk protein. If you are allergic to milk, do not use it. (Allergy is rare in adults; most people who think they are allergic are lactose intolerant.)
- Lactose intolerance. A concentrate can carry enough lactose to cause bloating and cramps. An isolate has under 1% and is tolerated by most lactose-intolerant people; ProEnergy is labelled safe for the lactose intolerant.
- Too much at once. Forty grams in one sitting can sit heavily. Start with one scoop.
- Digestive upset from the rest of the tub. Sugar alcohols, thickeners and artificial sweeteners in cheap powders are a more common cause of stomach trouble than the whey itself.
- Kidney disease. If you have diagnosed kidney disease, protein intake is something to set with your doctor, not a website.
- Pregnancy and nursing. Protein needs go up, and whey is a clean way to meet them, but check with your doctor or midwife first, as with any supplement.
Whey is naturally gluten-free. If you are buying a bar or a ready-to-drink, read the rest of the ingredient list.
Section 7
How to choose a whey protein: the checklist
Turn the tub over and read the panel, not the front. Nine things to look for:
Isolate, not concentrate
90%+ protein, almost no lactose, fat or cholesterol. The label should say isolate, and only isolate.
Cross-flow microfiltered
Chemical-free, low-temperature filtration that keeps the protein in its native form. Avoid ion exchange.
Full amino acid profile printed
All nine essential amino acids, with the BCAAs (leucine, isoleucine, valine) listed.
Low carbohydrate, zero sugar
Two or three grams of carbohydrate per serving at most. Anything more is filler or sugar.
Sweetened naturally, or not at all
Stevia leaf extract, or nothing. Walk away from sucralose, acesulfame-K, aspartame, colors and artificial flavors.
Non-GMO, gluten-free
Both should be stated. Whey is naturally gluten-free; the other ingredients may not be.
Grass-fed, no rBGH
Milk from pasture-raised cows not treated with recombinant growth hormone or routine antibiotics.
Cold-processed
Never heated to the point of denaturing. Denatured whey is still protein, but it clumps, tastes cooked and loses its minor fractions.
Short ingredient list
Five or six lines you can pronounce. No maltodextrin, no soy lecithin, no proprietary blend, no gums you cannot name.
How ProEnergy® scores
Every line above is on the ProEnergy jar: cold-processed, cross-flow microfiltered whey protein isolate from grass-fed cows not treated with rBGH; 20 g of protein in a 90-calorie scoop; zero sugar, zero fat, zero cholesterol; sweetened with stevia leaf extract; non-GMO, gluten-free, soy-free; five ingredients in vanilla, six in chocolate and one in unflavored; made in the USA in a cGMP-certified facility. See the three flavors →
Section 8
Seven whey protein myths
“It is only for bodybuilders.”
Whey is a food, not a gym product. The people who benefit most are the ones who skip breakfast, the ones trying to lose fat without losing muscle, and adults over 50, who need more protein than they did at 30 and usually eat less.
“It is full of artificial ingredients.”
Some tubs are. Whey itself is one ingredient. Read the list: if it is longer than six lines, the extra lines are the artificial part.
“Women will bulk up.”
Muscle is built by training and a calorie surplus, and women have a fraction of the testosterone that makes bulking easy. Protein on its own makes you leaner, not bigger.
“I am lactose intolerant, so I cannot use it.”
Concentrates carry lactose. A true isolate has under 1%, and most lactose-intolerant people tolerate it without any trouble.
“I will get all my protein at dinner.”
Your body cannot store protein for later. Around 25–40 g per meal, three or four times a day, builds and keeps more muscle than the same total eaten at one sitting.
“Protein powder is chalky and gritty.”
Denatured or badly filtered whey is. A cold-processed isolate dissolves with a spoon and tastes of very little, which is the point: it takes on the flavor of whatever you blend it with.
“It is not natural.”
Whey has been in the human diet for as long as cheese has. What is unnatural is the sweetener, colour and thickener list in the cheap tubs, and you can see those on the label.
Section 9
How much protein do you need?
There is no single number; it depends on your weight, your age and what you are asking your body to do. The figures below are grams of protein per kilogram of body weight per day, from all foods, not just powder. (Divide your weight in pounds by 2.2 to get kilograms.)
Sources: US Dietary Reference Intakes; International Society of Sports Nutrition position stand on protein and exercise (2017); PROT-AGE Study Group (2013).
Then divide it across the day. Aim for 25–40 g at each of three or four meals rather than 10 g at breakfast and 80 g at dinner. A typical American breakfast is about 10 g of protein; one scoop of whey in a shake brings it to 30. That single change is where most people get the most benefit.
More is not better past these ranges. Extra protein beyond what your body can use is simply burned as calories.
Section 10
When to take whey protein
Breakfast
The meal most people get wrong and the one where whey does the most good. A shake with protein, fruit and a little fat instead of toast or cereal keeps blood sugar level and appetite quiet until lunch.
Around training
Twenty to forty grams within a couple of hours of a workout, before or after. The old idea of a 30-minute window is overstated; what matters is that the protein arrives the same day and that your total for the day is right.
Instead of a meal you would skip
A shake beats nothing, and it beats most things you can buy through a window. Two scoops with fruit and nut butter is a complete meal.
Before bed, if you train hard
A slow protein like casein or a mix of whey and food protein before sleep supports overnight repair. Not needed for most people.
Section 11
How to use it
Whey isolate has a clean, almost neutral taste and dissolves in cold liquid, which makes it easy to put almost anywhere:
- A shake. 1 to 1½ cups of cold water or milk, one or two scoops, frozen fruit, ice. Five minutes. There are 24 recipes here.
- A shaker bottle. One scoop, 12 oz of cold water, ten shakes. No blender needed.
- Oatmeal or yogurt. Stir a scoop into either after cooking or straight from the fridge.
- Baking. Pancakes, muffins, energy balls. Whey tolerates baking; it just sets a little firmer than flour, so use a bit more liquid.
- Soups and sauces. Whisk a scoop of unflavored into anything warm, after it comes off the heat.
Whole fruit, not juice. Juice is fruit with the fiber removed, and it spikes blood sugar the way a soda does. Whole or frozen fruit gives the shake body, fiber and a slower release, which is the whole idea.
Section 12
Whey protein FAQ
Is whey protein isolate the same as whey protein?
Whey protein is the family; isolate is the most filtered member of it, 90% or more protein with almost no lactose, fat or cholesterol. When a label says only “whey protein” it usually means a concentrate.
How much whey protein should I take a day?
One or two scoops for most people, 20 to 40 g, as part of a daily total of roughly 1.2 to 2 g of protein per kilogram of body weight from all foods. The rest should come from meals.
Can I take whey if I am lactose intolerant?
Usually, yes, if it is a true isolate. The filtration removes nearly all of the lactose; ProEnergy is labelled safe for the lactose intolerant. If you have a milk allergy rather than an intolerance, do not use whey.
Does whey protein help you lose weight?
It helps in two ways: it keeps you full for longer than carbohydrate or fat, so you eat less without trying, and it protects lean muscle while you lose fat, so more of what you lose is fat. It does not burn fat by itself.
What is the difference between grass-fed whey and ordinary whey?
The milk. Grass-fed whey comes from cows on pasture rather than grain-fed and confined, and the good brands also guarantee no rBGH growth hormone and no routine antibiotics. The protein content is the same; the cleanliness of the source is not.
