Caffeine
Caffeine is a compound that is extremely common when browsing the supplement facts of a diet pill that may be under your evaluation. Acting as a psychoactive stimulant and diruetic, it has the effect of temporarily mitigating drowsiness and increasing your alertness. The FDA has stated that caffeine is “safe” ((http://edocket.access.gpo.gov/cfr_2003/aprqtr/21cfr182.1180.htm)).
Knowing your caffeine tolerance is definitely important when evaluating different dietary supplements. The effects of caffeine vary from person to person based on any number of factors (body size, tolerance, etc.). It’s well known that the effects of ingesting caffeine can be felt within an hour, and, with a mild dose, wear off within 3-4 hours.
It is undisputed that caffeine can have a positive and sometimes dramatic impact on workouts. An article published by Graham and TE in December of 1991 demonstrated caffeine’s effects on endurance workouts when trained runners showed a 44% increase in endurance ((http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=pubmed&dopt=AbstractPlus&list_uids=1778925)). The dosage used in the study was 9 milligrams of caffeine per kilogram of body weight. To give you an idea of the strength of that dosage, I weigh 175 pounds, which means my dosage would have been 716 mg, or approximately three and a half extra-strength caffeine tablets, 5 and a half 8 oz. cups of coffee, and 20 Coca-Cola Classic sodas.
That type of dosage is dangerously high, which would appear to then invalidate this study. However, another study showing a dosage of nearly half that (5.5 milligrams) per kilogram of body mass, boosting the subjects endurance level by 29% ((http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=pubmed&dopt=AbstractPlus&list_uids=7749424)). While that is still a very high dosage, it is not considered dangerous.
In a study done by Belza et al. in Copenhagen Denmark, published in the European Journal of Clinical Nutrition, it was determined that caffeine boosted metabolism by six percent, while Green Tea and tyrosine didn’t cause a statistically significant difference:
Results:Caffeine induced a thermogenic response of 6% above baseline value (72+/-25 kJ per 4 h, mean+/-s.e.) compared to placebo (P<0.0001). The thermogenic responses to GTE and tyrosine were not significantly different from placebo ((http://www.nature.com/ejcn/journal/vaop/ncurrent/abs/1602901a.html)).
Another study targeting healthy elderly citizens, 70 years or older, was done with the following conclusion:
Caffeine treatment increased epinephrine, fatty acids, lactate and norepinephrine [adrenaline] at different times during test session and led to insulin-resistance [insulin-resistance = hydrolysis = burning of fat]. Hence, caffeine ingestion elicits a similar metabolic response in elderly participants at 70 years old to that seen in younger subjects. ((http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=16886964&ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVLinkOut)) [comments added in brackets]
This is good news for those looking to caffeine as a potentially effective ingredient in a weight loss supplement.
Be advised that overuse of caffeine can be dangerous and hazardous to your overall health and well-being. Please weigh that in consideration of supplementing with any diet pill.