Review: Universal's M-Stack For HardGainers - Bodybuilding Supplements

Review: Universal’s M-Stack For HardGainers

Face it, you’re a classic “hardgainer”. This means you got fewer corners to cut. You gotta bust your ass, gotta work twice as hard and eat twice as much just to gain a hard earned pound of muscle. For you, the all new Animal M-Stak has been formulated. Animal M-Stak is the perfect hardgainer’s pack.

“Hardgainer” is probably a fair description of yours truly. I still shudder when I recall my last gaining cycle…my (now ex-) trainer had me on 3,000 calories/day (rather a lot for a 120 pound, 5′ 3 1/2″, middle-aged woman), but I still got stuck on a plateau. So the trainer-guy prescribed even more food. This got the scale moving again, but it was a hellish experience. I could barely get 3,000 calories-worth down as it was, so trying to get 3,300–3,400 kcals in was a nightmare.


So, basically, I’m “for” anything that can help add a little extra mass or a boost in strength, without having to endure another grueling “meal-a-thon.” Can M-Stak really live up to its promises? A look at the ingredients will provide some clues.

Natural Flavone/Sterone Complex 750mg
Ajuga Turkestanica Extract (Turkesterone)

Anti-Catabolic Amino Complex 3000mg
Leucine Alpha Ketoglutarate (AKG)
Leucine Ethyl Ester
Acetyl-L-Carnitine (ALC)

Energy Complex 500mg

Methylxanthine Complex (Caffeine, Theobromine, Theophylline)

Anabolic Adaptogen Complex 1000mg
Muira Puama
Kudzu Extract (Isoflavones)
Safed Musli
Rhodiola Rosea Extract (Rosavins)

Insulin Potentiating Complex 500mg
Banaba Leaf Extract (1-3% Colosolic Acid)
Cinnulin PF™ *
K-R-Alpha Lipoic Acid (K-R-ALA)

M Factor Complex 500mg

Ginger Root Extract (Gingerols, Shaogols)
6, 7-Dihydroxybergamottin

As is typical for this type of product, M-Stak is divided into several different proprietary blends, each with a specific function.

Natural Flavone/Sterone Complex: This blend contains several phytochemicals with reputed anabolic activity. These are:

  • Beta-Ecdysterone: Ecdysterones are steroids found in insects and a number of plants. According to an extensive review, “the metabolic fate of ecdysteroids in mammals, including humans, is only poorly known.” They appear to be non-toxic and—according to Eastern European/Soviet research—may have modest growth-promoting effects in animals. Recent in-vitro research suggests ecdysterones can increase protein synthesis in human and animal muscle cells, but more work will need to be done before they can be given an unequivocal “thumbs up” for building muscle or strength in humans.
  • 5-Methyl-7-Methoxyisoflavone: “Methoxy” is a derivative of ipriflavone, which is itself a derivative of the phytoestrogen daidzein. Ipriflavone has been investigated as an “alternative” treatment for osteoporosis, but does not appear to be very effective for that purpose. There is little published research on Methoxy itself, although it’s claimed to be an anabolic compound in two patents obtained by Chinoin, a Hungarian company. Methoxy has been promoted as a bodybuilding supplement for several years, but—anecdotally—the results have been less than spectacular.
  • Ajuga turkestanica Extract: Ajuga turkestanica is an adaptogenic plant and source of turkesterone, another ecdysterone.
  • Beta-Sitosterol: Beta-sitosterol is a plant compound with a structure similar to cholesterol. It has therapeutic uses for reducing serum cholesterol and treating the symptoms of benign protstatic hyperplasia (enlarged prostate).

Anti-Catabolic Amino Complex: This is a mixture of amino acids and related derivatives. It consists of:

  • L-leucine/L-valine/L-isoleucine: Collectively, these are known as the branched chain amino acids, or BCAAs. These essential amino acids play important roles in stimulating protein synthesis, reducing catabolism and delaying fatigue.
  • Leucine-Alpha Ketoglutarate: This is another form of leucine, bonded to alpha-ketoglutarate (AKG). As a Krebs Cycle intermediate, AKG is an important metabolite—but there’s little evidence that supplementing with it will improve either muscle gains or strength. Likewise, there’s no evidence that leucine-AKG increases leucine absorption/utilization compared to the free-form amino acid.
  • Leucine Ethyl Ester: That last sentence could be applied to leucine ethyl ester as well. Leucine ethyl ester was invented to take advantage of the (relatively brief) popularity enjoyed by creatine ethyl ester. This is straight out of Marketing 101, however…there’s no proof it works any better than taking plain ol’ leucine.
  • L-taurine: Research suggests that taurine can improve insulin sensitivity and reduce oxidative stress. In animal experiments, supplementation can mitigate the reduction in taurine levels following exercise.
  • Acetyl-L-Carnitine: Carnitine is an essential metabolite that’s critical for fat metabolism. The acetylated derivative is marketed as an anti-aging nutrient, as it has neuroprotective effects and—in combination with alpha-lipoic acid—has been shown to reduce oxidative stress and mitochondrial decay associated with aging.

Anabolic Adaptogen Complex: Adaptogenic plants are widely used in different folk medicine traditions around the world. The complex contains:

Insulin Potentiating Complex: The four ingredients in this blend are all known to improve glucose control and insulin sensitivity. They are:

  • 4-Hydroxyisoleucine: 4-hydroxyisoleucine exhibits insulinotropic activity and may enhance glycogen resynthesis after exercise.
  • Banaba Leaf Extract: Banaba is a tree native to Southeast Asia. The leaves are high in corosolic acid, which has been shown to improve glucose control in human and animal studies.
  • Cinnulin: Cinnulin PF® is a proprietary cinnamon extract. In a recent clinical study, subjects with prediabetes who took 500 mg/day for 12 weeks experienced modest, but statistically significant improvements in fasting blood glucose, blood pressure, and lean body mass.
  • K-R-Alpha Lipoic Acid: This is the potassium salt of R-alpha-lipoic acid, a potent antioxidant that can increase insulin sensitivity and glucose disposal in human and animal models.

Energy Complex: Caffeine and the structurally-related, stimulant compounds theobromine and theophylline should already be familiar to anyone who’s ever consumed coffee, chocolate or tea. The complex also contains evodiamine: a bioactive compound isolated from the fruit of Evodia rutaecarpa (used in Chinese traditional medicine as an anti-inflammatory). It’s similar to capsaicin in action, which is why it’s often found in over-the-counter weight loss supplements.

M Factor Complex: The compounds in this blend are known to enhance the absorption (Bioperine®) or alter the metabolism (6, 7-Dihydroxybergamottin, ginger) of a number of nutrients or drugs taken with them.

As you can glean from the above, M-Stak contains quite an array of compounds with a variety of physiological effects…some well-characterized, and others, not. They’re all quite safe, however, so I had no qualms about giving M-Stak a full trial run.

Unlike a lot of pre-workout products, M-Stak isn’t a powder. Rather, a canister of M-Stak contains 21, plastic-wrapped “paks” of tablets and capsules. Each canister supplies the precise number of paks for the recommended “3-weeks-on, 1-week-off” cycle. I took one pak per day—although I tossed the (optional) red “Energy Complex” capsule on non-workout days.

I didn’t detect any noticeable “buzz” or other sensation (good or bad) after taking a pak, but I definitely felt more alert and focused during and after my workouts.

Interestingly enough, I broke through a bench-press plateau during the second week of using M-Stak, and also improved (although less dramatically) on several other lifts. It may have been a coincidence, of course, although M-Stak contains components (BCAAs and adaptogens) that I generally respond well to.

Overall, I have mixed feelings about M-Stak.

On the one hand, it contains some questionable and redundant ingredients. In addition, dose is always an issue when it comes to proprietary blends: it’s difficult to know which compounds are provided in useful amounts, and which are simply “label decoration.”

On the other, some of the ingredients do have merit (or potential), and my short experience with it was generally positive. As such, I’d say it’s worth experimenting with, and I may come back to it at some future date for a longer trial.

Universal’s M-Stak is available at,
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Summary of Animal M-Stak
  • Contains a range of interesting bioactive compounds.
  • The BCAAs and adaptogens it contains have value for strength trainees.
  • Can be taken with/without the stimulant-containing “energy complex.”
  • Likely contains a certain amount of “label dressing”
  • Formula contains some questionable and/or redundant ingredients.

Author: elissa

Elissa is a former research associate with the University of California at Davis, and the author/co-author of over a dozen articles published in scientific journals. Currently a freelance writer and researcher, Elissa brings her multidisciplinary education and training to her writing on nutrition and supplements.

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