Clenbuterol – Thermogenic agents and body temperature

Although ephedrine works, it isn’t elegant. It is agonist for all of the other adrenoreceptors in addition to the B2 receptor. Biochemists have pursued pure B2 agonists that have no B1, A1 or A2 agonistic effects. The most popular, albuterol, has been around since the early 1970s. It’s better than ephedrine, but it’s not a perfect B2 agonist.
The B2 agonist that has gained worldwide attention is clenbuterol. An excellent oral asthma medication, it also has tremendous fat-burning and anti-catabolic properties. It is sold over-the-counter in many countries and is considered safe enough for use in liquid preparations for children and geriatrics. Clenbuterol uses a very unusual thermogenic pathway: brown adipose thermogenesis (BAT). There is much controversy among scientists about how much BAT happens, and at what stage of human life.

Most body fat is the type that we see in the meat department in the supermarket. The fat cells vary in size and adreno-or androgen receptor make-up, but other that that, fat is pretty uninteresting stuff – not all that different from the leftover scraps from a steak dinner. Scientists call it white fat, even though it’s kind of a pastel yellow color. Fat doesn’t have much color because its only blood circulation is from capillaries, which are very small. How small? A micrometer is 1/1000 th of 1 millimeter. Capillaries are between 5 and 20 micrometers in diameter. Oxygen reaches all of the cells of your body through red blood cells (erythrocytes). Red blood cells are about 7 micrometers in diameter. When a 7 micrometer wide red blood cell travels through a 5 to 20 micrometer wide capillary, you can bet they go through one at a time. Fat is whitish largely because very few red blood cells get through it. Most of the liquid circulating through the fat is straw-colored plasma. Fat that had a larger blood supply, from arterioles (branches of arteries) instead of capillaries, would be a different color. More red blood cells flowing through the fat would make it appear a dark orange-brownish color. Scientists call this fat brown fat. Why don’t they call it orange fat? I don’t know. Brown fat is different in many ways from regular fat. Not only does it have more red blood cells (which means more oxygen), but the cells also have mitochondria, which create energy. Let’s see… brown fat has more red blood cells, more oxygen, more mitochondria. Bingo! It’s a recipe for heat production. You’ve just cooked up Brown Adipose Thermogenesis, BAT for short. During the first few months of human life, brown fat is an important regulator of body heat. Babies have a lot more brown fat than adults. The remaining brown fat is located on your upper back between your shoulder blades. BAT, like muscle cell thermogenesis, is regulated through B2 adrenoreceptor stimulation by noradrenaline. You can actually feel the thermogenic effect between your shoulder
blades. Have someone place a hand there while you are using a thermogenic agent – it will feel warmer than the surrounding areas.

The lingering question for the scientists is this: Is the heat actually produced in the brown fat, or is the effect from hotter blood coursing through an area that has better circulation than the fat around it? Although many people want to think the heat comes from the brown fat, the evidence is beginning to suggest that BAT in adults is caused by hotter blood. Clenbuterol does more than just cause brown adipose thermogenesis. It is an agonist to all B2 receptors, including heat producing muscle. Clenbuterol is much more potent than ephedrine because it is has a much better receptor affinity. Clenbuterol burns fat better than both albuterol and metaproterenol. As an added bonus, it has anabolic and anti-catabolic properties that help to increase muscle mass while dieting. Bang! The initial research on humans contained some amazing body transformations. It looked as if the fat was turning into muscle. The Scottish University study hit the British newspapers in 1988, and I learned of it in time to include it in my Underground Steroid Handbook II. Talk about a bomb going off! By the time I re-entered the athletic community in 1990, clenbuterol use was in full swing. A totally fat sedentary slob sitting in an airport lounge in 1988 had turned into a national fitness model by 1990. I could fill another book with stories of such clenbuterol transformations.
Clenbuterol wasn’t ever approved by the FDA, but for a while it was easy to come by. It was imported for personal use. It was imported as a raw powdered research chemical and made (underground) into tables. It was easy to make human versions from the raw chemical. I’d whip up a few bottles of liquid clenbuterol drops for my friends in my own kitchen. As usual, the official party pooper put out Alert Bulletins to stop clenbuterol importation. Nevertheless, a lot of clenbuterol still sneaks into the country.
Clenbuterol is potent. A standart 20 mcg tablet is more thermogenic than a 25 mg tablet of ephedrine. Through almost 5 years of trial and error, we’ve refined its use as a thermogenic and anabolic agent. Clenbuterol has rattled sports organizations so much that it is often grouped in the same class as anabolic steroids! Currently, it is still legal to own and use in America. Although you cannot use the personal use exemption, you can legally bring it back from a foreign country with a foreign doctor’s prescription. Don’t be surprised if FDA puts it on the same schedule with steroids, making it much harder to acquire and use legally.

You might think that because I’ve helped research, refine and apply clenbuterol, I must be the de facto leader of the Clenbuterol Cult in America. That assumption is incorrect. I think that the athletic world became so enamored with clenbuterol because, besides anabolic steroids, there isn’t another drug with the same bang-for-the-buck, instant-
gratification attributes of clenbuterol. To anyone who has seen or felt its effects, they are eerily extraordinary.
I’ve seen some absolutely remarkable transformations over just a 2-week period. Body fat virtually vanishes and muscles grow bigger and more toned. Even at normal dosages of 2 to 5 tablets per day, clenbuterol has fewer side effects than ephedrine and, of course, much greater potency.

Nevertheless, I’m sorry to say that not everything is hunkydory with clenbuterol. This roaring thermogenic effect appears to last only 2 to 3 weeks before petering out rapidly. After the body adjusts to clenbuterol through a very complex down-regulation of the B2 receptors, body temperature cools back to near normal. This rapid attenuation of thermogenic and anabolic effect was noticed almost immediately in laboratory animal experiments. The researchers concluded that the B2 adrenoreceptors were down-regulating. First, the B2 receptors become increasingly insensitive to B2 agonists because of the higher temperature. Then, the receptors “burrow” into the cell so the agonist can’t reach them. Next, they are deactivated through phosphorylation of the receptor. Ultimately the actual number of receptors decreases. This is not earthshaking news. We’ve known this about natural adrenaline for decades. If there’s anything remarkable about these effects, it’s that the attenuation is so rapid. The researchers suggested a dosing schedule of 14 consecutive days of clenbuterol use, followed by an alternating schedule of 2 days off, then 2 days on. This appeared to reinitiate the benefical effects in the laboratory animals, but I don’t know how long this new dosing arrangement succeeded. However, in working with numerous athletes, I found that this strategy didn’t work for very long. The remarkable intensity of clenbuterol’s initial action doesn’t appear to repeat itself.
When reviewing blood test results of bodybuilders using clenbuterol, I noticed a pattern. Serum Free T3 levels would drop very much like classic Euthyroid Sick Syndrome. I theorized that clenbuterol was interfering with the T4 to T3 thyroid conversion. Cytomel works quite well to adjust the T3 level (and body temperature) back to normal. At this
point I was pretty happy with what was happening in Clenbuteroland. By combining the researchers’ dosing schedule (2 days on, 2 days off), and supplementing with thyroid hormone, we seemed to achieve a continuation of thermogenic effect. It wasn’t dazzling, but at least we got a consistent thermogenic effect without escalating the dosage of clenbuterol into the stratosphere. Some athletes were using 400 mcg (that’s 20 tablets) each day. Most people would say “case solved” and move onto other things, but I couldn’t leave it alone. Eventually, even with this careful dosage schedule, two things will happen. First, your B2 receptors will down-regulate. In addition, somewhere along the way your natural ability to produce adrenaline and noradrenaline will down-regulate, too. At this point, clenbuterol is not an addition to your body; it replaces normal production. The problem is that the damage is done already. Increasing the dosage of clenbuterol will just decrease the number of receptors and the amount of noradrenaline even further. Chasing your plummeting body temperature with additional T3 is initially effective and
somewhat benign, but escalating dosages of Cytomel will cause a suppresion of natural thyroid production and hyperthyroidism. When you finally stop using clenbuterol, there is a staggering systems crash. It will take at least 2 weeks (and usually more), for the adrenal system to become fully functional. Until then, alertness, body temperature and energy will be noticeably diminished. When coming off clenbuterol, athletes look and feel like, well, shit. It’s not
life-threatening and not like the kind of withdrawal caused by other drugs. It’s less severe and doesn’t last as long as withdrawal from anabolic steroids. Perhaps clenbuterol is best taken in infrequent 2-week dosing peridos every 2 months. Unfortunately, clenbuterol’s effects are so dramatic and enticing that most people won’t leave it alone.
Because of clenbuterol’s problems – its limited span of activity and unpleasant withdrawal effects – I have abandoned it. Although it is visibly effective and not entirely dangerous, its problems escalate with continued use. Unfortunately, it still happens to be the only useful anti-catabolic agent besides anabolic steroids. I now work with another, more potent, thermogenic agent that does not affect the adrenal system at all. As the compound is still under development, it is not discussed in this article. Researchers have recently isolated another adrenoreceptor that regulates heat production exclusively, the B3 receptor. Drugs that affect this receptor should produce a more tailored
thermogenic response. For now, however, B3 agonists are still in the research stage.


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Sara Viesca

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