I've recently had a surge of questions about how to lose weight, the best diet to follow, and what fat loss supplements folks should consider. I've covered some in the past, but I thought I'd touch on a few others that are surely gracing the sides of the supplement bottles you're probably staring at right now-either on your desk, or in the magazine next to you.
The question then arises; are any of these truly worth the money? I apologize in advance for some of the excruciatingly boring scientific jargon. I guess it comes with the territory of being in school for 10+ years.
Chromium is an essential trace mineral widely used in fat loss supplements.
In fact, according to a report in 1999, approximately 10 million Americans took chromium supplements and spent about $150 million per year on the ingredient, making chromium the second largest selling mineral after calcium.
This is despite the fact that many well-conducted studies using chromium have not supported its claims as a weight loss agent.
Chromium is sometimes referred to as glucose tolerance factor (GTF), although technically it is the active component of the complex. GTF is actually a complex of molecules found in the body that enhances the effectiveness of insulin.
Role Of Chromium
The role of chromium and insulin was discovered over 30 years ago, when researchers realized that chromium deficient humans on total parenteral nutrition also exhibited signs of insulin resistance and hypercholesterolemia; these signs were reversed with chromium supplementation.
Subsequently, researchers have speculated that chromium supplementation might be an effective treatment for diabetes and hypercholesterolemia, with more recent claims suggesting that chromium will enhance body fat loss and lean body mass gains, because of its connection with
The initial thoughts of how chromium acts in the body is related primarily to enhancing the cell's sensitivity to insulin, thereby increasing the muscle cells uptake of amino acids, and subsequently improving lean body mass. This increase would then result in an elevated resting metabolic rate, and incidentally, body fat loss.
Studies In Chromium
One study published considered many of the aforementioned parameters regarding chromium supplementation. This 12-week, double-blind, placebo controlled study tested the effects of 400 µg/day of chromium picolinate supplementation on body composition, resting metabolic rate, and strength along with several other biochemical parameters.
Thirty-seven subjects completed the study, with each participating in a supervised exercise program, to increase compliance among subjects.
All subjects also completed diet records to reduce the confounding factor of energy changes or difference throughout the 12-week protocol. The results at the end of the study showed that supplementing with 400 µg/day chromium picolinate for 12-weeks had no significant effects on any of the outcome parameters measured: body composition, resting metabolic rate or strength.
Other studies found similar results when assessing the effects of chromium, body composition and
strength gains. Yet, this has not swayed eager consumers from trying to find the magic bullet when it comes to weight loss; a majority of the well-controlled studies using chromium supplementation as a means for weight loss, show it is ineffective.
The more exciting area of research with this mineral is its potential connection to those with diabetes, but even here it appears that the true benefit may be realized if an individual is chromium deficient, not in someone who is not.
Coleus forskohlii is an herb that has been used since ancient times to treat heart and respiratory disorders; more recently, it has been added to weight loss products as well. Herbal product manufacturers are now producing Coleus forskohlii extracts with elevated levels of the constituent forskolin.
Although no full-length manuscripts have been published measuring the effects of this herb on fat loss, there is currently one published abstract. The logic behind its inclusion is apparent when considering its mechanism.
Coleus forskohlii stimulates the enzyme adenylate cyclase, which in turn catalyzes the conversion of ATP to cAMP, which, as described earlier in the chapter, increases the effects of hormone sensitive lipase to break down triglycerides.
| What Does cAMP Mean?
A form of AMP (adenosine monophosphate) used frequently as a second messenger in eukaryotics and in catabolite repression in prokaryotes.
Studies In Coleus Forskohlii
The one small study completed to date provided six overweight women with 250 mg Coleus forskohlii, standardized to provide 10% (25 mg) of forskolin twice daily for 12-weeks.
At the end of the study, the authors found no statistical difference in body weight or body fat, over the 12-week period. This is only one small study; however, at this time it is the only published evidence regarding this particular supplement.
Consequently, it is safe to say that while the use of Coleus forskolii appears useful on paper, this conclusion can not be drawn without more evidence to support or refute the statement. Moreover, there is concern regarding its safety and efficancy as forskolin may worsen cardiovascular conditions, by causing vasodilation and lowering blood pressure.
Hydroxycitric Acid (HCA)
HCA is produced from the rind of the fruit of Garcinia cambogia, which is native to India and popular as a food additive in Asian cultures.
In America, HCA has grown in popularity and its inclusion in weight loss aids is common. However, this popularity has not resulted in many well-controlled human research studies assessing the claims; most of the supportive literature is in rodents.
Early research has shown that administration of HCA inhibits the extramitochondrial enzyme ATP citrate-lyase, which catalyzes the cleavage of citrate to acetyl-CoA and oxaloacetate. This is a crucial step in lipogenesis, which would lead one to believe that administration of HCA would enhance fat loss.
Van Loon et al published a small study measuring the acute effects of HCA on substrate oxidation in humans in 2000. This study was designed to determine if HCA would enhance fat oxidation during bicycling; this is important because increased fat oxidation is one of the purported mechanisms of HCA and, if true, one that could increase fat loss.
Ten cyclists participated in this pilot study; subjects were provided with a flavored beverage that contained 0.5 g/kg body weight of HCA, resulting in a total of 18 0.4 g HCA over the entire HCA trial.
At the end of the trial, it was determined that HCA concentrations were elevated higher than would be expected with the doses used in previous studies and what is included in most-weight loss products; no other human trials have measured plasma HCA, however, but this study alleviated concern that HCA may not be absorbed.
Although plasma HCA levels were elevated, this did not translate to increased fat or carbohydrate oxidation rates, suggesting that this mechanism of action does not contribute to weight loss. There is still thought that HCA may inhibit dietary intake as another mechanism, thereby enhancing weight loss.
Therefore, Leonhardt and colleagues investigated the effect of HCA on feeding behavior, body weight regain, and metabolism after weight loss in male rats. This 22-day feeding study fed ad libitum diets to two groups of rats. The rats were first all fed 10 g of a standard rodent diet for 10 days intended to cause weight loss.
The rats were then divided into two groups and matched for weight loss and body weight. They were then fed one of two diets (one provided only 1% fat and the other provided 12% fat) and within each group, one group of rats was supplemented with 3g/100g HCA, while the other solely at the rodent diet.
The results showed that HCA did cause a reduction of body weight regain in both groups. Similarly, the rats consuming the 12% fat diet (but not the 1% diet) had a significant long-term suppressive effect on food intake suggesting that the increased fat content was necessary for this change.
Unfortunately while these results show promise, it is difficult to extrapolate them to humans because the dose of HCA provided would be extremely high in humans; this is not cost-effective.
The small amount of data available utilizing HCA as a weight loss aid in humans does not provide solid evidence that it is effective.
While the rodent data appears promising, the doses utilized have been much higher than those used in human studies and the human studies have not solely considered HCA but rather as a component of a proprietary formula. This makes it impossible to tease out the individual effects of each component.