by Cy Wilson:
Alpha-Lipoic Acid
This substance has been shown in both human and animal trials to increase insulin sensitivity in skeletal-muscle tissue. This can improve glycogen storage and can help in terms of allowing more glucose to be shuttled into muscle cells as opposed to the extra glucose in the bloodstream being shuttled into fat cells. In other words, you can prevent some adipocyte (fat cell) hypertrophy to some extent even when you increase carb intake to a fair amount. Lastly, this substance is also a potent antioxidant.(3,4,5)
Rating: 7
Aspirin
In theory, aspirin could help to increase the efficacy of ephedrine and caffeine and that’s why it’s often included in many fat burners. But when researchers actually looked to see exactly how much aspirin contributed to the overall efficacy of ephedrine and caffeine, they found that it had little, if any, effect. (Despite this, many supplement makers are still including "A" in their ECA stacks.)
Now, normally, it wouldn’t be a big deal if you included something that may or may not help ephedrine and caffeine much in terms of efficacy, but in this case, aspirin can be potentially harmful. It’s been shown that as little as 10 to 75 mg can cause gastrointestinal bleeding in normal humans. This can be life threatening in some cases. Definitely not worth an added 1% in efficacy. (6-11) Also note that some companies use white willow bark, which is sort of an herbal aspirin.
Rating: 1
Bergenin
This compound has little research behind it. The only study I found was performed in vitro using rat fat cells. This compound was shown to enhance the mechanism of lipolysis but didn’t itself increase lipolysis. (12)
Rating: 2
Carnitine
This amino acid has been included in a few formulations because of its textbook roles in fat metabolism. Essentially, it transports long-chain fatty acids into the mitchondria to be oxidized and it also modulates the metabolism of coenzyme-A.
So does this mean it’ll increase fat oxidation? Not likely. Carnitine isn’t something that would normally be depleted in the human body. However, if you’re in a severely calorie-deficient state for a prolonged period of time and don’t consume much meat, then you may, in theory, benefit. Even so, there isn’t really any evidence supporting its use. (25)
Rating: 2
Ephedra
This plant is present in most formulations and it contains more than one ephedrine isomer. Ephedrine is great but when you evaluate the data behind each of the other isomers, you find that they each have a unique property. For instance, ephedrine itself is the best in terms of beta-2 agonism and nor-ephedrine is the best appetite suppressant. Overall, ephedra sinica, which contains four ephedra alkaloids, is certainly the most potent substance we have in terms of reducing fat.
Rating: 9.5
5-HTP
This is the direct precursor to the neurotransmitter serotonin and it works by simply elevating levels of this neurotransmitter. Why is this important? Well, when you diet, serotonin levels drop rather significantly and this is what causes carbohydrate cravings that lead to eating three boxes of cookies after working so hard to stay "strict" all week.
Because 5-HTP increases serotonin production, numberous studies have shown it to aid in weight loss and drastically reduce carb cravings, and thus carb intake. It’s also been well documented that 5-HTP can elevate mood or relieve some depression in certain individuals.(22,23,24)
Rating: 9
Forskolin
This substance, in theory, should work since its ability to stimulate cAMP production (which increases lipolysis) has been well documented. However, does this mean it’ll actually work in humans? It looks hopeful at this point and forskolin is getting a reputation for being a natural, non-suppressive thyroid booster.
Fellow contributor Doug Kalman wrote a great piece and reviewed the current literature supporting forskolin as a weight loss supplement. Give it a read here.
Rating: 8
Ginger (Gingerols, Shogaols) and Red Pepper (Cayene, Capsaicin)
These compounds have been shown to increase energy expenditure and oxygen consumption via adrenal catecholamine secretion (mostly epinephrine) and there’s actually some research in both humans and animals. The problem? Well, yes, an increase in energy expenditure is usually a good thing as long as what’s being oxidized are lipids and not carbohydrates. When you increase carbohydrate oxidation, you essentially end up exhausting glycogen stores while preserving fat stores. Well, this is exactly what capsaicin has been shown to do! And ginger is nearly as potent as capsaicin in this regard. So, it’s pointless to add these to any formulation. (13-17)
Rating: 0
Green Tea (Catechin-Polyphenols)
Green tea actually has a good amount of research in humans to support its efficacy. People used to think it was only effective because of its caffeine content, but researchers have found that the catechin-polyphenols contained within actually have an effect independent of caffeine.
One study found that green tea elevated energy expenditure whereas caffeine itself had no effect. Researchers believe that this is accomplished by the catechin-polyphenols’ ability to inhibit the enzyme responsible for the degradation of norepinephrine (meaning that norephedrine’s fat-burning effect lasts longer) and thus explains the increase in urinary norepinephrine excretion in humans. (18,19)
Rating: 7.5
Guarana
This has been put in many fat burners as a replacement for caffeine, which is what’s normally used in the ephedrine/caffeine stack. Since guarana contains caffeine, people think that it’s just as good as plain old caffeine in terms of results. However, a while back some researchers compared caffeine to coffee, which contains caffeine just as guarana does. What they found was that even though the amount of caffeine used was the same, the coffee had no effect in terms of the parameters measured for lipolysis, whereas the caffeine alone did.
So does this mean that perhaps guarana isn’t as effective as pharmaceutical-grade caffeine? Maybe. But I’m going to be safe in this case and only stick to those products which contain pure caffeine.
I think the reason certain companies use guarana is because it sounds more exotic than just plain old caffeine, not to mention the average person thinks "herbal" or "natural" means it’s better for you. I guess that means snake venom and tobacco are too, huh? Skip the guarana and use caffeine.
Rating: 4
Synephrine
This biogenic amine has been added to many formulations in the past few years and at first was touted as an "ephedrine replacement." Well, as many people found out, it’s far from that and isn’t nearly as effective. Still, it’s been shown to possess some beta-adrenergic activity, both at the beta 2 and beta-3 receptor. ("Beta-adrenergic," in really simplified terms, means, for the purposes of this article, that the compound in question increases heart rate and has an overall thermic, or heat producing effect. As such, the compound helps the body burn more fat.) The problem as I see it, is that it doesn’t activate lipolysis (fat burning) very well and there’s a lack of research in terms of safety. (1,2)
Rating: 3
Tyrosine
This amino acid serves as the raw material for many important compounds that are associated with dieting. It’s basically a precursor to the all-important metabolism controlling thyroid hormone T3, and a precursor to the "feel good" neurotransmitters epinephrine, norepinephrine, and dopamine. Neurotransmitter stimulation can help maintain optimal thyroid output during a strict diet. Not only that, but Tyrosine has been shown to increase the effectiveness of substances like ephedrine.
Rating: 6
Yohimbine
This substance has been around for a few years and certainly has its place among effective lipolytic agents. An alpha-2 antagonist, it binds to alpha-2 receptors and essentially allows lipids to be mobilized from adipocytes that normally wouldn’t be released very easily. Alpha-2 receptors are basically responsible for those "problem areas" of fat storage, like the obliques in men and lower body in women. Yohimbine could help target those areas. It has a good amount of research behind it, so it’s not just a theoretical notion.(20,21)
Rating: 9.5
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