Muscle Feast Review: Grass-Fed Whey Isolate & Micellar Casein

In this article I’ll share my experiences & opinion on three Muscle Feast products I’m very familiar with:

  • Grass-fed Whey Isolate (unflavored)
  • Grass-fed Micellar Casein
  • Grass-Fed Whey Isolate (chocolate)


I’ll discuss their ingredients, nutrition facts, & amino acid profiles, as well as other important features such as their manufacturing practices & product purity standards.

And I’ll compare these Muscle Feast protein powders head-to-head with those made by the biggest elephant in the fitness supplement room, Optimum Nutrition.


Muscle Feast review summary

Muscle Feast’s grass-fed whey isolate and casein products are purer, cleaner, and have a better nutritional profile than a majority of the protein powders available these days.

These particular Muscle Feast products are very reasonably priced, considering the extra lengths the company goes to in order to maintain this higher standard.

The whey isolate product I review in this article has an excellent buyers’ satisfaction rating of 94% across the online world, with over 1,400 reviews giving it a combined 4.7⭐ rating.



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Science resources included

As is my custom here on heydayDo, I will provide links to all of the relevant sports science & medical resources, clinical studies, and nutritional data used in this article.



Muscle Feast & me

My intro to Muscle Feast’s products came about because several months ago I decided to ‘relax’ my long (two decades’ long) allegiance to the protein powders made by Optimum Nutrition., and explore a cleaner option for my daily go-to whey.

The reason I started looking for a better quality protein product was motivated by a simple health-based goal:


Reduce my daily pounding of a product that has unwanted artificial sweeteners.



I’m cool with Optimum Nutrition…

…but I decided to go real clean with my main protein powder.

For one, my diet is already real clean and has been for decades: I’ve been growing my own organic vegetables & fruits for years.

And two — when I hit the grocery store, I’m real picky about what products make it into my basket.


So why not apply the same standard to my supplements?


Not sure why it took awhile for that light bulb to go on…

…but when it did it was an easy, logical personal choice to search for affordable protein products that were as free of additives as I could find.


After a bit of nosing around the crowded protein powder world, Muscle Feast’s grass-fed whey isolate & casein became my new 1-2 protein punch.


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Click on the blue name or its pic to check current price or read Muscle Feast Amazon reviews.


Muscle Feast Grass-Fed Whey Isolate

(For this part of the review I’ll be looking at their unflavored powder, which is the one I drink. It comes in 4 other flavors: Mocha, Chocolate, Vanilla, & Strawberry Cheesecake.)

Notable features

Excellent owner satisfaction

94% 4&5-star rating, 4.7⭐ from 1,400+ online reviews


Minimally processed

  • Undenatured – means no acids, no heat
  • Cold microfiltration – means non-chemical, no ion exchange

These high-quality processing methods are much different than your run-of-the-mill whey powders.


Very clean

Muscle Feast’s grass-fed whey isolate has none of these things in it, unlike many mass-produced protein powders:

  • artificial sweeteners or colors
  • “natural” artificial flavors
  • fillers or other additives
  • amino spiking
  • sugars or sugar alcohols
  • soy
  • gluten

Also, being a whey isolate almost all of the lactose has been removed, making it well-tolerated for people who have trouble digesting milk and regular whey powders.


Nutrition facts

Muscle Feast nutrition facts - heydayDo image

  • 90% of each serving is protein
  • Low sodium compared to other brands
  • Negligible sugar & fat


Amino acid profile

Muscle Feast amino acid profile - heydayDo image

  • 5 grams of BCAAs per serving



Muscle Feast ingredients - heydayDo image

As you can see, there are only two ingredients, whey protein isolate and sunflower lecithin.


Whey protein isolate

Bottom line: Purest protein source available.

* By definition, whey isolate has at least 90% protein, as fat & lactose have been removed. (1)

* Sports science has shown that weightlifting supplemented with whey isolate yields significant increases in muscle & strength. (2)

* Studies have also shown whey isolate aids muscle recovery from exercise-incurred damage. (3)


Sunflower lecithin

Bottom line: It’s an emulsifier added to make mixing the protein powder with liquid a lot easier.


Sunflower lecithin comes straight from nature, and is extracted from sunflower seeds. (4)

Its role in foods & drinks is to make unlike things blend together easily, which in our case refers to water and protein powder. (5)

Actually, sunflower lecithin is a popular health supplement that’s been shown by medical science to provide a few benefits:

  • lower cholesterol
  • improve digestion
  • help breastfeeding moms
  • may improve heart & brain health (6)


Muscle Feast cost analysis

Muscle Feast current cost/gram of protein: 4¢

Compare that to these brands after standardizing everyone to 25 grams of actual protein, which is in the dosage range recommended by the International Society of Sports Nutrition (7):


Muscle Feast Grass-Fed Whey Isolate                  $0.91 (per 25g)

Isopure Whey Protein Isolate                                   $0.96

Opportuniteas Grass-Fed Whey Isolate               $1.11

Optimum Nutrition 100% Whey Isolate              $1.24

Legion Whey+ Isolate                                                  $1.51


Bearing in mind that online prices often change… 

…you can see that currently, Muscle Feast’s grass-fed whey isolate is the cheapest of all the best 100% whey isolate products.



How much protein powders really cost

Quick programming note worth mentioning…

Cost per gram of actual protein — not the cost of the whole powder — is the best way for me to determine true prices of protein powder products.

Cost per serving is not a good indicator, nor is price per ounce like Amazon shows us on product pages.


This is because so many protein powders have something in them besides pure protein, and the amount of that something varies widely.

Some protein powders are over 90% protein by weight, others are in the 70% range. 




1. My taste buds are very finicky nowadays, compared to 30 or 40 years ago. I think eating real clean food for years has something to do with it, but I’m just guessing.

2. I have been drinking milk &/or milk products like whey & casein powder my entire 60+ years of life. Me & milk are tight.

3. I believe we each have our own unique taste preferences, so my opinion about how something tastes doesn’t really matter anyways.


For me, Muscle Feast’s unflavored whey isolate is very easy to drink; it tastes like skim milk.


Definitely more like skim milk than say a powdered milk product like Nestle’s Carnation, which I had to drink as a kid for awhile and am still bitter about.


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A note regarding other Muscle Feast flavors:

I started with their chocolate flavored version since I’d been drinking Optimum Nutrition’s chocolate flavored whey blend all those years.

I did NOT like the taste of Muscle Feast’s chocolate whey isolate.

They use way too much stevia in it for my taste buds, and that was a couple of years after they supposedly reduced the amount of stevia in it.

I switched to unflavored and my taste buds thanked me.



Thanks to the lecithin, this whey isolate powder mixes easily in a shaker bottle.

I gave it 5 or 6 seconds of low-energy shaking, and it was blended & clump-free.


Grass-fed whey isolate summary

Muscle Feast’s unflavored grass-fed whey isolate powder is a very clean, two-ingredient product made with very good manufacturing practices.

It has excellent nutritional & amino acid profiles.

And it costs less than its whey isolate competitors, some of whom include unwanted artificial sweeteners or those darn Natural Flavors.

The unflavored version tastes good and is easy to mix too.

See reviews & current price on Amazon



vs. Optimum Nutrition whey

Muscle Feast Whey Isolate vs Optimum Nutrition Whey - heydayDo image

I’ll be comparing this Muscle Feast grass-fed whey isolate to the O.N. product I drank forever, their Gold Standard Double Rich Chocolate whey isolate blend. 


Buyer ratings

Muscle Feast                 92%, 4.8 – 1,400+ online reviews

Optimum Nutrition    90%, 4.6 – 20,000+ online reviews


O.N.’s Gold Standard Whey is the biggest selling protein powder in the world, and those 20,000+ reviews are your proof.



The Muscle Feast whey isolate has just the two ingredients, while Optimum Nutrition’s has all this:

Optimum Nutrition Whey ingredients - heydayDo image


Things to note

  • “Natural flavors” are artificial, as you may know (8)
  • Artificial flavors & artificial sweeteners
  • Not pure whey isolate – may cause lactose issues
  • The lecithin here is soy
  • Harsher production using heat, acids, chemicals


Nutrition Facts

Optimum Nutrition Whey nutrition facts - heydayDo image


Protein % per serving

Muscle Feast               90%

Optimum Nutrition   79%



Muscle Feast                      0.2 grams

Optimum Nutrition          1.5 grams



Muscle Feast                    0.2 grams

Optimum Nutrition        3.0 grams


Amino acid profile

Optimum Nutrition Whey BCAA label - heydayDo image

* Muscle Feast Whey Isolate & Optimum NutritionWhey Blend have a similar amino acid content (around ~5g of BCAAs per serving), although Optimum Nutrition doesn’t publish their amino profiles.



Compared to the clean milk taste of Muscle Feast’s unflavored whey, the O.N. powder tastes processed, given it has two artificial sweeteners in it, sucralose & acesulfame potassium.


But I think it’s OK and drinkable.


And the Optimum Nutrition chocolate whey tastes a lot better than the chocolate whey version Muscle Feast makes, due to the excessive stevia taste Muscle Feast uses that I mentioned earlier.



Optimum Nutrition’s Gold Standard whey mixes very easily, like Muscle Feast’s powder does.



Again, the comparison is with cost per gram of protein, and then standardized to a 25 gram serving size.

Optimum Nutrition      $0.70 per 25g

Muscle Feast                   $0.91


Summary: O.N. vs Muscle Feast

* Optimum Nutrition costs less but still delivers the same amount of protein & branched-chain amino acids as Muscle Feast’s grass-fed whey isolate.

* Optimum Nutrition’s whey blend may cause issues for those who are lactose intolerant, since it is not a pure whey isolate.

* O.N.’s whey powder has artificial sweeteners and soy in it while Muscle Feast’s powder is very clean.

* Muscle Feast’s manufacturing processes are gentler on the whey than Optimum Nutrition’s. This may result in better micronutrient quality, though those things are hard to measure.

See O.N. reviews & current price

See Muscle Feast reviews & current price


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Muscle Feast grass-fed micellar casein

(For this part of the review, I’ll be looking at their unflavored casein, which is the one I drink.)

Muscle Feast Micellar Casein Unflavored - heydayDo image

Notable features

Very good owner satisfaction

89% 4&5-star ratings, 4.6⭐ from 300+ online reviews

(The score for unflavored is much higher than these numbers indicate. Most of the negative reviews were due to the taste of their flavored versions, and reviews of all flavors get dumped into 1 overall rating on Amazon & elsewhere.)


Nutrition facts

Muscle Feast Casein nutrition facts - heydayDo image

  • Protein % per serving: 83%

Amino acid profile

Muscle Feast Casein amino acid profile - heydayDo image

  • 4.3 grams BCAAs per serving



Muscle Feast Casein ingredients - heydayDo image

Just like its whey isolate sibling, this MF casein only has two ingredients:

  • micellar casein
  • sunflower lecithin


Micellar casein

Casein is sold in two forms, hydrolysate & micellar.

Micellar casein is the slow-digesting form, ideal for taking at night before bed. (9)



My unflavored casein tastes like milk, plain & simple, so I’m all good with that.

And like the chocolate whey isolate they make, Muscle Feast’s chocolate casein has too much stevia in it…for my taste buds anyways.

But since casein is a richer & naturally slightly sweeter milk product than whey isolate, the stevia doesn’t dominate nearly as bad…so I’m OK with it.




For casein, this mixes really well in a shaker bottle.

Other caseins I’ve tried — including Optimum Nutrition’s — can mix in a shaker fine, but need more elbow grease for sure.


Muscle Feast micellar casein cost

  • cost per gram of protein: 3.5¢
  • cost per 25 gram serving: 88¢


Bottom line summary: Muscle Feast grass-fed micellar casein is another excellent protein product that’s very clean & nutrient-rich with an affordable price.

I love the unflavored version and easily recommend it.

But I dislike the flavored caseins Muscle Feast makes due to their taste.

See reviews & current price on Amazon


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vs. Optimum Nutrition casein

Muscle Feast grass fed casein vs Optimum Nutrition casein - heydayDo image

For this comparison, this Muscle Feast grass-fed casein will go up against another Optimum Nutrition product I drank for years, their Gold Standard Micellar Casein with the Chocolate Supreme flavor.



Optimum Nutrition casein ingredients - heydayDo image

Again, Muscle Feast uses only two ingredients — micellar casein & sunflower lecithin — while Optimum Nutrition has a whole lot of non-protein things in theirs, notably:

  • Natural & artificial flavors
  • Artificial sweetener sucralose
  • Artificial sweetener acesulfame potassium
  • Fillers (“Gum Blend”)
  • Added salt
  • Soy lecithin
  • Proprietary blend called Aminogen**

**Aminogen is a mystery concoction marketed by supplement companies as an aid to protein digestion. 

Search online and you’ll see a lot of supplement sites selling Aminogen who will tell you about a research study that showed how effective it is. 

Tsk tsk. That study was run by Triarco Industries, the company that produces & markets Aminogen. (10)  😏


Nutrition Facts

Optimum Nutrition casein nutrition facts - heydayDo image


Lots of salt

Optimum Nutrition has 280 mg of sodium in each serving of their casein.

That’s over 1200% more salt than is in Muscle Feast’s casein (280mg vs. 23mg).


% of protein per serving

Muscle Feast                   83%

Optimum Nutrition      70%



Muscle Feast                 0.5 grams

Optimum Nutrition    1.0 grams



Muscle Feast                1.2 grams

Optimum Nutrition   4.0 grams


Amino acid profile

Like with their whey, Optimum Nutrition doesn’t publish its amino acid profile.

They simply state on the package “nearly 5 grams of BCAAs”.

Muscle Feast’s casein has 4.3g of BCAAs, so I guess we can call that a wash, given O.N.’s vagueness on the matter.



Like with their whey comparison, Muscle Feast’s unflavored casein tastes better to me than O.N’s casein & its artificial sweetener afterglow. 😜

But my taste buds like Optimum Nutrition’s Chocolate Supreme more than Muscle Feast’s chocolate casein product.



Both mix easily, though the Optimum Nutrition needs a little more energy to get it done.

This is because it’s a thicker product thanks to that gum blend filler.



Cost per gram of protein standardized to a 25 gram dose:

Muscle Feast                      88¢   (per 25g)

Optimum Nutrition     $1.05


Casein comparison summary

Bottom line: I think the Muscle Feast unflavored grass-fed micellar casein easily shows itself to be the superior protein powder in this duel.

  • It’s actual protein cost is cheaper (19% less)
  • It delivers a higher % of protein per serving
  • 30% of the O.N. serving isn’t even protein
  • Too much salt in the O.N. casein
  • O.N. uses several artificial ingredients

See Optimum Nutrition casein reviews & current price

See Muscle Feast casein reviews & current price


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Wrapping Up

heydayDo's Lil Boji and the Muscle Feast Review - heydayDo image

Related protein powder articles here on heydayDo

The Hunt For The Best Optimum Nutrition Flavor

MyProtein Impact Whey vs. Optimum Nutrition Gold Standard

Syntha-6 Stone Cold Creamery Protein Powder Review


I hope that my in-depth look at Muscle Feast’s grass-fed whey isolate & micellar casein protein powders is useful to you, and that the comparisons to similar products from Optimum Nutrition is helpful too.

I wish you well on your fitness journey; let’s go.

– greg

About heydayDo

heydayDo author Greg Simon
Hi I’m Greg Simon. Fitness training & nutrition researching since 1982. Organic food & wine grower. Surfer. Congenital heart disease survivor (so far). Read more…
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