PX Black Review


PX Black is the sequel to FinaFlex’s fat-burner, PX. In terms of ingredients, it is pretty similar but the difference, slight as they may be, do help to enhance the overall efficacy…


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PX Black is the sequel to FinaFlex’s fat-burner, Pro Xanthine (PX). In terms of ingredients, it is pretty similar but the difference, slight as they may be, do help to enhance the overall efficacy…[Skip to the Bottom Line]


1,3,7-trimethylxanthine, more commonly known as Caffeine, generally serves a key ingredient in stimulant-based fat-burners because of its ability to release Noradrenaline, which induces lipolysis (fat-breakdown). Although this mechanism can certainly burn fat in the short-term, prolonged Caffeine consumption (by itself) generally results in tolerance build-up so the effects become less potent over time. This was demonstrated in a 1992 study in which 24 weeks of Caffeine intake (200mg/day) failed to induce weight-loss in humans. For Caffeine to be an effective fat-loss agent, it must be combined with other stimulants or synergistic compounds such as EGCG. Fortunately, PX Black contains several other stimulants as well as non-stimulant synergistic compounds such as EGCG and Naringin.


Naringin is a polyphenol commonly found in Grapefruits and some other citrus fruits. A 2008 study from “Phytotherapy Research” found that Naringin was able to stimulate peroxisome proliferator-activated receptors (PPAR) activity in vitro, a mechanism which can induce fat-loss via the release of Adiponectin (a protein which facilitates the breakdown of fat). These results lend credibility to the already established notion that Naringin is one of the main polyphenols responsible for the weight-loss benefits of Grapefruit, noted in several studies.

It’s not clear how much Naringin is present in the PX Black formula but, based on its position in a 815mg proprietary blend, we’d estimate no more than a couple hundred mg.


Hesperedin, similar to Narangin, is a polyphenol commonly found in citrus fruit. A 2008 study from “Phytotherapy Research” found that Hesperedin was able to stimulate peroxisome proliferator-activated receptors (PPAR) activity, in vitro. Stimulation of PPAR receptors is generally associated with the release of adiponectin, a protein involved in the breakdown of fat. A later (2012) study noted that injections of Hesperedin in the stomachs of rats stimulated brown adipose tissue, generally indicative of an increase in metabolic rate. Although this study used injections, the dose used was within the practical limits of oral consumption.

The exact amount of Hesperedin in PX Black remains unclear, but there is no reason to suspect FinaFlex has included far less than an optimal 100mg dose.


Sulbutiamine is an analogue (chemical relative) of Thiamine (Vitamin B1), the benefits of which pertain mostly to fatigue. A 1999 study found that subjects suffering from chronic post-infectious fatigue who consumed 400 and 600mg of Sulbutiamine experienced significant reduction in over-all fatigue compared to the placebo group. These findings were replicated in a 2003 study, published in “The Journal of the Association of Physicians of India”, in which subjects (again with infection-induced fatigue) who consumed 400mg reported significant reductions as well. Unfortunately, since both of these studies involved patients with some sort of medical ailment, it’s difficult to say how effective Sulbutiamine would be in healthy persons, and even more difficult to say how this anti-fatigue effect may translate to physical performance (if at all). There are absolutely no studies regarding the potential of Sulbutiamine for weight-loss nor is there any reason to suggest it would be beneficial in any way.

Needless to say, PX Black does not contain 400mg of Sulbutiamine (or even half that), so it’s tough to gauge how effective it is here. That being said, at whatever dose, it may possibly help to alleviate some of the fatigue generally experienced by those on a calorie/carb-restriction.


Theobromine belongs to the same class of chemical compounds as Caffeine, known as Methylxanthines. While its CNS stimulant properties are less potent than Caffeine, it is alleged to increase heart rate to a greater degree, potentially enhancing oxygenation. Unlike Caffeine, Theobromine has not been extensively studies with regards to its effect on physical performance so an optimal dose has not been established.


As far as Phenylethylamine’s direct effects on weight loss, studies are more or less non-existent. However, PEA triggers the release of Catecholamines (Noradrenaline, Adrenaline, etc.) the general physiological reaction of which is activation of the beta-adrenergic receptors which induce lipolysis. So the mechanism by which PEA may induce weight loss is theoretically sound, just not documented. Because the effects are generally short-lived, it is hardly a miracle weight-loss supplement on its own, but combined with compounds such as Hordenine (which FinaFlex has also included in PX Black), which blocks the rapid oxidation of PEA in the brain, the effects can be amplified and practically relevant.


Hordenine (chemical name N, N-dimethyltyramine) remains relatively under-researched, despite its escalating popularity in pre-workout and weight-loss supplements. Oral doses have been shown (in animals) to augment Noradrenaline-induced muscle contraction while not directly inducing contractions itself, indicating that it works as a monoamine reuptake inhibitor. So, rather than acting as a stand-alone stimulant, Hordenine can amplify/extend the effects of other stimulants by blocking the reuptake of Noradrenaline (and other Monoamines).


Yohimbine acts as an alpha-2 receptor antagonist, meaning it inhibits the receptor responsible for blocking lipolysis. By blocking the action of this receptor Yohimbine allows for more lipolysis to occur than would normally be permitted by the alpha-adrenergic receptors.

A 2006 study, published in “Research in Sports Medicine”, found that supplementation with 20mg daily (2 10mg doses) induced significant fat-loss in athletes (Soccer players) over a two week period.

Given its role as an alpha-receptor antagonist, Yohimbine may be synergistic with other stimulants such as Synephrine and Caffeine which tend to induce lipolysis via beta-receptor agonism. Although FinaFlex does not disclose the exact dose of Yohimbine in the PX Black formula, even just a few mg can have a meaningful impact when combined with the other stimulants.


3,5 diiodothyronine, also known as T2, is one of the primary Thyroid Hormones which, until recently, was thought to be relatively inactive compared to the others. However, recent research indicates that T2 can influence Thyroid signaling, though perhaps to a less potent degree than the other Thyroid Hormones. For individuals with a healthy functioning Thyroid, 3,5 diiodothyronine supplementation likely won’t induce any considerable changes with regards to bodyweight. On the other hand, individuals with low levels of Thyroid hormones which may be causing weight-gain, or preventing weight-loss, may benefit.


A 2010 stduy, published in “Chemico-biological Interactions”, found that Oleanolic Acid significantly improved blood glucose tolerance and reduced body weight in obese rats. A 2011 study from “Phytotherapy Research” replicated these findings, and further attributed to the mechanism of action to anti-oxidant and insulin-signaling properties. Overall, Oleanolic Acid still has not been extensively studied in humans, so the benefits are hard to gauge, but the potential for weight-loss (or weight-management) is certainly present.


The fat-burning potential of Green Tea Extract has been studied pretty extensively, with all of the research pointing to Epigallocatechin gallate (EGCG) as the compound primarily responsible for the effects.

A 2009 study, published in “The Journal of Nutrition”, found that subjects consuming 625mg Green Tea Catechins (EGCG) alongside 40mg Caffeine paired with exercise lost an average of 2.2kg (4.8lbs) compared to the subjects in the control group (consuming just Caffeine), who lost an average of 1kg (2.2lbs). These findings were corroborated by a 2009 meta-analysis, published in the “International Journal of Obesity”, which concluded that Green Tea extract tended to cause about 1.2kg (2.6lbs) reduction in bodyweight, and that effects could be amplified with Caffeine in non-caffeine tolerant individuals.

Further research has revealed that EGCG can effectively block Catechol-o-Methyl Transferase (COMT), the enzyme responsible for the degradation of Catcholamines such as Noradrenaline. The result is an indirect increase in Noradrenaline which induces lipolysis. So, while EGCG is not likely to induce noticeable weight-loss alone, when combined with Caffeine or other Noradrenaline-releasing stimulants, it can be quite synergistic.

FinaFlex does not disclose the exact dose of Green Tea Extract in PX Black, but given a 345mg proprietary blend, one serving cannot yield an optimal dose of EGCG. Still, there may be some benefit, especially at more than one dose daily.


N-Coumaroyldopamine is a compound found in several species of plant, but most commonly extracted from Cocao. A 2005 study, published in “The FASEB Journal”, found that N-Coumaroyldopamine was able to increase cAMP via beta-adrenoceptor agonsim, in vitro. Although these findings should be viewed as strictly preliminary, they do suggest that N-coumaroyldopamine has the potential to be used as a fat-burner in humans, sharing the same mechanism of action as such compounds as Synephrine. FinaFlex does not disclose the amount of N-Coumaroyldopamine in PX Black, but given there is no “optimal” dose, it would be impossible to interpret anyway.


Advantra Z is a patented form of Bitter Orange Extract which has pretty clear implications for weight-loss in humans.

A 2011 study, published in the “International Journal of Medicinal Sciences”, found that supplementation of 50mg Syneprhine increased the metabolic rate in human subjects without affecting blood pressure or heart rate.

Similarly to Ephedrine, Synephrine is a beta-receptor agonist and an alpha-receptor antagonist, the combined effect of which is an increase in lipolysis. While the exact amount of Advantra Z in PX Black is not listed, it doesn’t take much to initiate fat-burning, especially in combination with some of the other fat-burning agents FinaFlex has included.


A 2011 study, published in the “International Journal of Medical Sciences”, found that, while Synephrine alone (50mg) was able to achieve a 65kcal increase in resting metabolic rate (RMR), the combination of Naringin (600mg) and Synephrine (still 50mg) resulted in an RMR increase of 129kcal. Furthermore, the addition of 100mg Hesperedin to that combination elevated RMR by 183kcal.

Unfortunately, PX Black does not contain 600mg of Naringin and probably doesn’t contain 50mg of Synephrine. That being said, there may still be some combined benefit.


PX Black has some pretty significant fat-burning potential, especially at 1.5 servings daily (the recommended upper limit according to FinaFlex). The majority of this benefit can be attributed to the diverse range of stimulants present in the formula as well as synergistic non-stimulant ingredients such as EGCG and Hordenine. At about 65 cents per serving, PX Black is competitively priced compared to other stimulant-based fat-burners and is worth trying for anyone who can tolerate heavy doses of stimulants.


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