Whey concentrate and whey isolate come from the same milk protein; isolate is filtered further, so it is at least 90% protein with very little lactose or fat, while concentrate ranges widely in protein content and keeps more lactose and fat. "Grass-fed" describes how the dairy cows were raised, not a federally defined measure of protein quality, and once milk is made into whey powder the nutritional differences are small.
Key takeaways
- Whey is the liquid left over when milk is made into cheese. It is filtered and dried into concentrate or isolate.
- Isolate is 90% or more protein with about 0.5% lactose. Concentrate ranges from about 25% to 89% protein, so the grade matters.
- "Grass-fed" and "rBGH-free" are farming claims. Neither one is a measure of protein quality.
- The International Society of Sports Nutrition (ISSN) suggests 1.4 to 2.0 g of protein per kg of body weight per day for most people who exercise, spread over meals every 3 to 4 hours.
- To compare products, look at grams of protein per scoop and scoop weight, not the size of the tub.
How whey is made
Milk protein is roughly 80% casein and 20% whey. When cheesemakers curdle milk, the casein forms the curd and the whey stays in the liquid. That liquid is mostly water and lactose, so it is filtered through membranes to concentrate the protein and remove lactose, minerals and some fat, and then dried into powder. "Ultra-filtered" refers to this membrane step.
The degree of filtering determines the product:
| Form | Protein | Lactose | Milk fat |
|---|---|---|---|
| Whey powder | 11–14.5% | 63–75% | 1–1.5% |
| Whey protein concentrate | 25–89% | 10–55% | 2–10% |
| Whey protein isolate | 90% or more | about 0.5% | about 0.5% |
Source: composition ranges compiled in Hoffman and Falvo, 2004.
Concentrate vs. isolate: which matters for you
Isolate is the better choice if lactose is a problem for you or if you want the most protein per calorie. Because most of the lactose is removed, many people who are sensitive to lactose tolerate it. Note that isolate is not lactose-free, and it is still a milk product.
Concentrate keeps more of milk's other components, along with a little more lactose and fat. Its range is wide: a concentrate at 80% protein and one at 35% are very different products, which is why the protein-per-scoop number matters more than the word on the front of the tub.
If you tolerate lactose, the practical differences are cost, taste and grams of protein per serving.
What "grass-fed" and "rBGH-free" mean
Grass-fed means the cows ate a pasture- or forage-based diet. The USDA used to have a grass-fed marketing standard, but it withdrew that standard in January 2016. Since then, grass-fed claims have relied on private or third-party standards, and those standards differ. The claim says something about how the animals were raised. It is not a federally defined statement about the protein.
The nutritional differences in grass-fed milk show up mainly in the fat. A US study of 1,163 milk samples found that milk from cows fed entirely grass and forage had a lower ratio of omega-6 to omega-3 fats (0.95, compared with 5.77 in conventional milk) and more omega-3 overall. Whey powder, however, is mostly protein with very little fat, so only a small amount of that difference reaches your shaker. The amino acid makeup of the whey is essentially the same. The case for grass-fed whey is mostly about sourcing and farming practices.
rBGH-free (also written rbST-free) means the cows were not given recombinant bovine growth hormone, a manufactured hormone used in some dairy herds to increase milk output. The FDA has stated that no significant difference has been shown between milk from treated and untreated cows. Cows make natural bovine somatotropin, so no milk is entirely free of it. Like grass-fed, rBGH-free describes a farming choice, not a nutritional upgrade.
Leucine, muscle protein synthesis and how much you need
A note before the research: the studies below describe whey and protein intake in general, not the finished MAXIS product.
After a workout, muscle protein synthesis rises, and eating protein raises it further. The amino acid leucine is a key trigger. The ISSN position stand on protein and exercise suggests 700 to 3,000 mg of leucine per serving, along with the other essential amino acids. It notes that proteins that digest quickly, are rich in essential amino acids and supply enough leucine are the most effective at stimulating muscle protein synthesis. Whey fits that description.
In a 2009 study, three groups of six young men did leg exercise and then drank whey hydrolysate, casein or soy protein, each matched to provide 10 g of essential amino acids. After exercise, muscle protein synthesis was about 122% higher with whey than with casein and about 31% higher than with soy. That study measured a short-term response, not muscle growth over months.
What matters most over time is total daily protein combined with consistent training. The ISSN recommends:
- Daily: 1.4 to 2.0 g per kg of body weight for most people who exercise. Higher intakes may help resistance-trained people preserve lean mass while dieting.
- Per meal: about 0.25 g per kg, or 20 to 40 g in absolute terms.
- Spacing: evenly distributed doses every 3 to 4 hours.
For a 75 kg (165 lb) person, that works out to roughly 105 to 150 g of protein a day, or about 19 g or more per meal across four or five meals. Food can supply all of it; a shake simply fills gaps.
Timing matters less than most people think. The ISSN notes benefits from protein taken either before or after a workout, that the effect of exercise on muscle protein synthesis lasts at least 24 hours, and that total daily intake is a stronger predictor of muscle gain than precise timing. If you ate a protein-rich meal within a few hours before training, there is no need to rush a shake afterward.
How to read protein per scoop
Scoop weight and protein content are not the same thing. A 30 g scoop with 20 g of protein is about 67% protein; the rest is flavor, sweetener, carbohydrate and fat. To compare products, divide grams of protein by scoop weight, and check how many servings the tub actually contains.
Flavor can affect the number too. Ingredients such as cocoa powder take up part of a scoop, so two flavors of the same product may not deliver the same protein. Our own formulas show this, as described below.
Where MAXIS Grass-Fed Whey fits
Each 2 lb tub of MAXIS Grass-Fed Whey contains 37 servings. Vanilla provides 19 g of protein per scoop of about 24 g, from a blend of concentrate and isolate. Chocolate provides 17 g per scoop. It is mostly concentrate, and the cocoa takes up part of the scoop, which accounts for the 2 g difference. Both have 100 calories, 2 g of sugar and 2 g of fat per scoop. They are ultra-filtered, rBGH-free and sweetened with stevia and monk fruit. Protein helps build and repair muscle when paired with resistance training.†
Both contain milk, and the chocolate also contains soy lecithin. If you are also taking creatine, the Strength Stack pairs Vanilla whey with MAXIS creatine monohydrate.
FAQ
Is whey isolate better than concentrate?
Not for muscle protein in general. Isolate is a better choice if you are sensitive to lactose or want the most protein per calorie. For everyone else, a good concentrate works well.
Is grass-fed whey more nutritious?
Only slightly, if at all. Grass-fed milk differs mainly in its fat profile, and whey powder contains little fat. Most people who choose grass-fed whey do so because of how the cows are raised.
Can I use whey if lactose bothers me?
Many people tolerate isolate, which contains very little lactose, but sensitivity varies from person to person. Whey is a milk product, so it is not suitable for anyone with a milk allergy.
References
- Jäger R, Kerksick CM, Campbell BI, et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14:20. DOI
- Hoffman JR, Falvo MJ (2004). Protein – Which is Best? Journal of Sports Science and Medicine, 3(3):118–130. PMC
- Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM (2009). Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology, 107(3):987–992. PubMed
- Benbrook CM, Davis DR, Heins BJ, et al. (2018). Enhancing the fatty acid profile of milk through forage-based rations, with nutrition modeling of diet outcomes. Food Science and Nutrition, 6(3):681–700. DOI
- USDA Agricultural Marketing Service (2016). Withdrawal of United States Standards for Livestock and Meat Marketing Claims. Federal Register, January 12, 2016. Federal Register
- US Food and Drug Administration (1994). Interim Guidance on the Voluntary Labeling of Milk and Milk Products From Cows That Have Not Been Treated With Recombinant Bovine Somatotropin. Federal Register, 59(28). GovInfo
†These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
