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Information courtesy of Par Deus One of the major contributors to body weight homeostasis in the human body is the sympathetic nervous system, the principal components of which are the catecholamines (epinephrine and norepinephrine) and the andrenergic receptors. There are two types of adrenergic receptors, alpha and beta, as well as subtypes of each -- and depending on which are activated, lipolysis (breakdown of fat) can be either stimulated or inhibited. The most well-known adrenoreceptors to bodybuilders are the beta receptors. These can be divided into subtypes 1, 2, and 3 -- and it is through these receptors that drugs such as the ephedrine/caffeine stack and Clenbuterol exert their effects. While Clenbuterol acts directly on beta 2 receptors, ephedrine exerts its effects indirectly by stimulating the release of norepinephrine (NE), the body's primary endogenous thermogenic hormone. Unlike Clenbuterol, NE is not selective in its binding. In addition to binding to the beta 2 receptor, it also binds to both alpha receptors, as well as the beta 1 and 3 receptors. It is in regards to its binding to the alpha 2 receptor that yohimbine comes into play.
Ativation of the alpha 2 receptor inhibits the release of NE. Thus, by binding to this receptor, NE functions as its own negative feedback signal. In other words, it shuts off its own release. Obviously, this is not a good thing for fat loss. This is particularly true at rest (which, unless you are a marathon runner is 95% of your day) -- this is because alpha 2 receptors are activated at lower catecholamine levels than are the beta receptors (1). Thus, thermogenesis is basically always turned off. It is the differences in regional distribution of alpha 2 and the beta receptors that is responsible for the gender differences in bodyfat storage (2). Basically, females have a large number of alpha 2 receptors and few beta receptors in the gluteofemoral area (hips, thighs, and butt), while men have the same problem in the midsection. With exercise or the use of compounds such as the ephedrine/caffeine stack, catecholamine levels can be increased to a point where the alpha 2 induced inhibition of lipolysis is partially overcome (1). However, even then, the alpha 2 receptors ARE still acting to reduce lipolysis. Yohimbine is a selective alpha 2 antagonist (3) and can thus short circuit this feedback loop, maximizing NE levels, thus maximizing fat loss, particularly in these problem areas.
A second, more indirect, mechanism by which Yohimbine can aid lipolysis via the adrenergic system is by increasing peripheral blood flow (4, 5). Adipose tissue is known to have rather poor vascularity. When triglycerides are broken down into free fatty acids and glycerol during lipolysis, they must also be transported away from the fat cell or they risk being reincorporated into adipose tissue. Beta receptor activation causes vasodilation, thus increasing blood flow, however, it does not increase enough to remove all of the free fatty acids released during lipolysis (6). Alpha 1 and 2 receptor activation, on the other hand, causes a decrease in blood flow (2, 7). Thus, antagonism of the alpha 2 receptor with yohimbine would be expected to increase blood flow, and thus increase the mobilization and disposal of these FFA's, further aiding fat loss.
Quite a bit of confusion seems to exist about the difference between Yohimbine and yohimbe. Yohimbine is the principal alkaloid from the herb P. yohimbe. However, there are 31 other yohimbane alkaloids that can be present in herbal yohimbe preparations. Some of these have different and unknown selectivities and potencies (and thus, effects) at the adrenergic receptors (8, 9) -- in addition, these preparations vary greatly from brand to brand and even from batch to batch, as no standardization for extraction exists. In fact, a recent investigation found that most over the counter preparations have little to no actual yohimbine (10). And, even in the more potent preparations, most people find a higher degree of undesirable effects with the herb vs. pure Yohimbine (due to the afore mentioned 31 other yohimbane alkaloids that can be present).
Studies have concluded that the ideal dosing for Yohimbine is .2mg/kg (11) -- this would be 20mg for a 220lb person (0.09 mg/lb of body weight). Studies using smaller dosages have produced less favorable results. At this level, little to no side effects have been reported (Keep in mind, this is with Yohimbine HCl, not the yohimbe herb). Another thing to be considered when using yohimbine is that insulin completely blunts its lipolytic effects, thus it should ideally be used on a low-carb/ketogenic diet, or at the very least, first thing in the morning on an empty stomach, followed by moderate aerobic activity for an extended period.
Amount per 1/4 tsp: 410mg We recommend using a scale to accurately dose this item due to it's potent nature and low dosing.
Customer Reviews for Yohimbine HCL Powder (1 gram) by NutraPlanetGreat with aerobic exercise By: WestonReview posted on: Wed Sep 30 13:28:12 -0400 2009 I've found the catecholamines to be a great addition to a trimming phase of my exercise plan, and Yohimbine HCl powder is the cheapest and most potent catecholamine agonist I've found. I usually only take 10-15mg (180lbs), and it really ratchets up the nervous system (as catecholamines do). I don't use the Yohimbine HCl powder with weight training however because it does burn up muscle tissue as well as fat. Keeping muscle tissue is more important to me than cutting up, and I don't want to lose my gains. For that reason I use the Yohimbine sparingly, maybe once or twice a week. It's most potent with caffiene, as the research clearly shows. I've also found it's most effective when you're glucose levels are already low and you're hungry. This helps to supress appetite (especially while running) and even keeps your hunger away for a couple hours until it begins to wear off. I'm not one of those who will do a ECA stack more than once a day, and while Ephedrine does lead to tolerance, I haven't noticed any potency decreases with Yohimbine, possibly because the receptor mechanism is quite different. I've also noticed on Yohimbine HCl that my sides (where my little amount of fat is) get quite warm, which is most undoubtedly thermogensis. This really might be working to target the fat areas, even though this claim sounds too good to be true. I don't know for sure whether it's really targetting those areas, but as a male, the feeling of thermogenesis is definitely on the sides of my abdomen where the fat stores are hardest to trim off. This is well worth the buy. 1 gram lasts me about 70 doses. Now that is cheap! Forget ephedrine tablets. |
