Caffeine is a known ergogenic aid in terms of enhancing endurance performance, increasing mental alertness, and, for many of you, enabling you to peel your eyes open in the morning. Chitosan has weaned in popularity in recent years, but many products still contain this ingredient, which purportedly enhances fat absorption and excretion. Let's take a look at the research.
Caffeine is often the cornerstone of many fat loss supplements because of its well-documented effects on thermogenesis and lipolysis. However, it is not necessarily considered as a stand alone product intended to enhance fat loss; rather, it is included with other ingredients with the intention of producing a synergistic effect.
Caffeine exerts its effects in a number of ways. It effects lipolysis by inhibiting a specific enzyme necessary allowing HSL to continue on its thermogenic pathway of breaking down triglycerides.
In addition, it also appears to stimulate energy expenditure vis a vis increased sympathetic nervous system, and has been suggested to enhance lipolysis. However, results from in vitro studies demonstrate that caffeine also works synergistically with adrenaline to enhance lipolysis. Therefore, the metabolic effects of caffeine appear to come from other mechanisms as well and not solely the interaction with the sympathetic nervous system.
A recent study sought out to ascertain where the lipolytic effect of caffeine is derived from: lipid oxidation or via the sympathetic nervous system. This may provide information for supplement manufacturers to design products around the functioning of caffeine, when considering what ingredients would work synergistically to enhance fat loss. There were eight male volunteers in this study who were given either caffeine or placebo; heart rate, energy expenditure, substrate utilization and free fatty acid turnover were all measured.
The results from this study demonstrated that caffeine ingestion increased energy expenditure (~13%), lipid turnover and oxidation. However, this study and others shows that caffeine has a much greater effect on lipolysis than on energy expenditure, which the authors note as a "pharmalogic model of stimulated lipolyis". They also note that from this study, it is apparent that caffeine exerts its effects through both sympathetic and nonsympathetic components.
It is important to note that high doses of caffeine can also have some negative side effects. Studies have demonstrated that caffeine may elevate blood pressure and heart rate, as well as result in diuresis, with one study suggesting high doses of caffeine may elicit loose bowels or diarhea.
A regular cup of coffee contains approximately 100 mg of caffeine (which will vary with bean type, length of brewing, etc), so caution is advised when taking doses of caffeine that are much higher than this.
While some dietary supplements are purported to increase metabolic rate or enhance fat metabolism, others, like Chitosan, are supposed to decrease the amount of fat absorbed and digested.
Chitosan is essentially a N-deacetylated form of chitin that is extracted from the shells of crustaceans. In the simplest terms, it is a type of positively charged fiber; the goal with use of this product is that it will bind to the negatively charged fat in the intestine and excrete it, similar to the pharmaceutical agent, Orlistat. However, while in theory this sounds promising, the results of the studies which have been published are equivocal.
A recent study published by Mhurchu et al, suggested that treatment with chitosan did not result in a clinically significant change in body weight compared to placebo. This 24-week, double-blind, placebo-controlled, randomized trial was completed on 164 male and female subjects.
At baseline and every four weeks thereafter, until the endpoint, subjects completed the following assessments: weight, waist circumference, blood pressure, capsule count, and adverse events. Furthermore, at baseline, 12- and 24-weeks, blood samples were taken to gather information on serum lipids; it seems logical that if chitosan does in fact decrease fat absorption, there would be a positive effect on lipid levels too.
At the end of 24-weeks, the researchers found no significant changes among any of the outcome variables measured. Those in the chitosan group lost just over 0.5 kg more than the 24-week study period; however, this is not statistically or clinically significant. This study also combined lifestyle and dietary advice throughout the program to all subjects and concluded that "it therefore seems appropriate to focus public attention on the proven effective means of weight loss such as improved nutrition and increased physical activity."
There are some safety concerns with chitosan as well. Although supplementing with chitosan does not appear to be effective at enhancing weight loss, research has suggested that use of this supplement does in fact enhance fat absorption and elimination. Because of this, one common side effect is diarrhea. Moreover, there is concern that some minerals and fat-soluble vitamins would be excreted as well.
As usual, my recommendations will stay the same. The best way to enhance fat loss is through eating fewer calories and, in particular, diets high in refined carbohydrates, saturated fats, and not enough lean protein.
In addition, kick up those cardio workouts (see article last week (right)) and you'll be on your way to a new beach body.
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