The World of Caffeine (52 page)

Researchers L.Dlugosz and M.B.Bracken comment on these findings:

Thus, although the effect of large doses on fertility in men is still undetermined, moderate doses of caffeine may even help a man to father a child, and the dynamics of caffeine’s effects on sperm seem to resemble those ascribed to alcohol on sexual performance in the traditional aphorism, “A little stimulates; a lot depresses.”

Once upon a time, men who wished to set themselves on a thorny quest chose to pursue the Holy Grail, the cup used by Christ at the Last Supper, a draught from which would confer all earthly and heavenly benisons. Today the quest for the Grail has been replaced by the quest for a “fat pill,” a safe, pharmacologically active chemical that a person can ingest to reduce and keep off excess fat. Presumably the scientist who discovers and the first company that markets such a wondrous medicament will eclipse Bill Gates and Microsoft as the greatest financial success story in modern times.

The key words here are “safe” and “reduce and keep off.” Many stimulants, especially powerful ones such as amphetamines and cocaine, effectively suppress appetite and increase metabolic rates. In other words, they help burn fat at a faster rate than normal. The problem is that their use is not safe and that, irrespective of their dangers, the capacity, at least of cocaine, to reduce your appetite seems to wear off as usage continues. A full range of amphetamine derivatives have been legal prescription drugs for decades, but they are rarely prescribed today, as some of them once were, as treatments for obesity or aids for weight loss. To fill the void left by their removal, natural medicine enthusiasts have marketed a variety of quack nostrums promising to “burn fat” or “speed up metabolism.”

Despite repeated claims of tabloid headlines touting these breakthroughs, few people believe that such a fat-burning substance actually exists or is even in the early stages of development. The amazing truth, however, is that common caffeine might be the fat-burning wonder drug everyone has been looking for all along.

Dr. John William Daly, one of the most respected researchers on the pharmacology of caffeine, states in his 1993 review paper “The Mechanism of Action of Caffeine”
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that, in addition to its effects on the cardiovascular, respiratory, renal, and central nervous systems, caffeine affects adipose (fat) tissue by stimulating lipolysis, that is, by increasing the catabolism, or burning, of fat. Additionally, caffeine partially blocks the effect of adenosine and adenosine analogs, neurotransmitters that inhibit lipolysis. In other words, caffeine enables your body to burn fat faster and might help you to lose weight.

There is some clinical evidence of this effect. People undertaking exercise studies under controlled conditions demonstrate more weight loss if their exercise was preceded by a very hefty dose of caffeine. Caffeine increases the level of circulating fatty acids, so-called free fatty acids, or FFA, released from adipose tissue. Between one and two hours after consumption, or according to other studies, three to four hours or more after consumption, caffeine has been shown, under certain conditions, to increase the oxidation of these as fuel and hence to enhance fat oxidation. Caffeine has been used for years by runners and endurance athletes to improve performance, presumably by enhancing fatty acid metabolism. It seems effective in those who are not habitual users. Some studies suggest that this effect is most pronounced during longduration low-intensity exercise, where lipids play a more important role in energy production, and that the effects are most noticeable in persons who are not highly trained athletes.

Caffeine may also work in other ways to help weight loss. It increases basal metabolic rate and resting metabolic rate, in both lean and obese subjects, by as much as 15 percent, and keeps these rates elevated for at least two hours after ingestion.
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Additionally, there is ample anecdotal evidence that caffeine, like other stimulants, such as amphetamine and cocaine, is an appetite suppressant.

The practical question remains: Can caffeine be an effective aid to weight loss, and if so, under what conditions and to what degree will it augment the efforts of diet and exercise in shedding pounds? As with so many questions about caffeine and health, the answer seems to be a combination of “it depends” and “nobody knows.” There have been many studies of the interaction of caffeine and exercise and of the effects of caffeine on levels of FFA and fat oxidation. The conclusions are apparently contradictory, providing support for just about any combination of conclusions you might choose to argue. The effects of caffeine on energy output, endurance, and fat metabolism vary widely on account of many factors: the complexity of the human system, the variations in how much caffeine is consumed, how long before the trial it is consumed, how long the exercise is continued, the physical condition of the subject, the tolerance of the subject to caffeine, and which muscles are being used in the exercise. Psychogenic effects may also be important: People may not perceive themselves as growing tired when they have ingested caffeine, and therefore they may continue their efforts longer. More carefully designed studies are needed to define the contributions of this slew of confounders. Meanwhile, there is good evidence that caffeine can help at least some people doing some exercises to do them longer and burn more fat while doing them.

There is a widespread conviction among many athletes and sportsmen that caffeine boosts performance in terms of endurance and energy output, and that, in short, using caffeine helps you to increase your speed and capacity to lift weights, and in
general to excel in athletic pursuits. Many long-distance cyclists, runners, and crosscountry skiers use caffeine during competition. Even racehorses are sometimes doped with and tested for caffeine.

The belief in the power of caffeine to augment athletic capacity is reflected in a 1962 decision by the International Olympic Committee (IOC) to restrict caffeine use by participants in the games to a urinary concentration of 15 mg/litre. The uncertainty about the effects of caffeine is reflected in the IOC’s repeated flip-flops over whether to continue restricting it and, if so, how much to allow in the serum levels of participants. Subsequent to the initial ban, the IOC dropped caffeine from its list of restricted drugs, and then, in 1984, restored it. Athletes alleged that, because of wide variations in the metabolism of caffeine among individuals, consumption of as little as 350 mg had caused some participants to nearly flunk the test. Because readings above the allowable level are regarded as deliberate attempts to “dope” the athlete, a 1988 study by researcher van der Merwe attempted to determine how much caffeine would put a competitor out of action. He administered varying amounts of caffeine by serving coffee, tea, and soft drinks to nine healthy subjects, within a fifteen-minute period. Although the doses ranged up to 1,000 mg, as much as in ten cups of coffee, no urinary levels were found to exceed 14 mg/litre, as measured three hours after ingestion. Consistent with other researchers, van der Merwe found that about 75 to 90 percent of the ingested caffeine appeared in the urine and the observed concentrations were independent of the dietary source. He concluded that it was impossible to flunk the IOC test as a result of the ordinary consumption of caffeinated beverages and that any athlete who failed to pass should be presumed to have resorted to caffeine to enhance his performance.
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Although a number of athletes have run into trouble over their urinary levels of caffeine, so far the IOC itself has disqualified only one participant on this account, an Australian pentathlon competitor in the Seoul Olympics in l988.
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Interest in caffeine’s benefits to exercise increased in the late 1970s after studies from the Human Performance Laboratory at Ball State University suggested that 200 mg of caffeine exerted a significant effect on an athlete’s endurance. Other studies have failed to confirm this conclusion, and some have suggested that the observed improvements were a consequence of a placebo effect. Determining the answer comes down to evaluating whether caffeine has ergogenic effects—that is, whether it can improve aerobic performance or the capacity of the body for physical work.

The body gets the energy needed to power muscles in at least three different ways, depending on whether the energy expenditure is of short, moderate, or extended duration. Energy is also burned differently by muscles of different sizes. For example, the large muscles of the legs, used in treadmill walking, burn energy differently from the smaller leg muscles, primarily used in cycling, which may be more responsive to the benefits of lipid mobilization. In addition, people in excellent physical condition, such as athletes, burn energy differently from people in a more ordinary state of dilapidation. Other variables include caffeine dose, pre-exercise food consumption, and individual variations in response and tolerance. All of these factors confuse our attempts to make sense out of the apparently inconsistent research findings about the effects of caffeine on energy output, endurance, and weight loss.

The basic theory underlying claims that caffeine can improve athletic performance is based on three assertions. The first is its ability to increase the efficiency with which the body burns fat, already alluded to in the weight-loss discussion above. This is considered the primary source of caffeine’s power to act as an ergogenic aid and to increase endurance for intense exercise, especially when duration approaches or exceeds one hour. Increased FFA mobilization delays the depletion of glycogen by encouraging the muscles to use fat as fuel, making the spared glycogen available to delay exhaustion, especially at high exercise intensities for which glycogen sparing is critical. This effect is minimized at exercise below the anaerobic threshold, that is, in low-intensity exercise, and experiments have shown that ingesting 400 mg of caffeine before such exercise did not affect either FFA or carbohydrate utilization.

The second claim is caffeine’s ability to reduce the rate of glycogen consumption— that is, it increases the efficiency with which the body burns sugars. Because glycogen is a primary source of energy for exercise, exhaustion occurs and exercise intensity must generally be reduced once glycogen has been depleted. This glycogen-sparing effect is greatest in the first fifteen minutes of exercise, during which glycogen utilization declines as much as 50 percent. The saved glycogen remains available during the later stages of exercise with the result that the athlete can continue longer before exhaustion occurs.

The third assertion is caffeine’s power to lower the rate of perceived exertion (RPE)—that is, to reduce our sense of fatigue. Some studies have shown that when athletes are asked to rate how hard they are working, some report significantly less exertion after consuming caffeine.

The popularity of sports snacks is increasing as athletes and exercisers search for anything that can give them an edge. When the National Academy of Sciences evaluated six purported performance boosters for the U.S. Army, the only ones they endorsed as effective were those that contained carbohydrates or caffeine. Although other ingredients might show promise, no claims can be supported without further research. These conclusions have been bolstered by studies, such as the one which demonstrated that the intake of sucrose, with or without caffeine, improved running time and distance from about forty minutes and six miles to about fifty-five minutes and nine miles.
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Other studies showed that consumption of about 900 mg of caffeine, which produce urinary levels just within the limits of the IOC, increased endurance time from fifty to more than seventy minutes.

In their quest for a chemical means of improving performance, many turn to over-the-counter combination products that contain both caffeine and ephedrine. An example of such a product is Formula One, a nostrum touted by its manufacturers as the “world’s first scientifically valid, gimmick free approach to weight management,” which contains a combination of ma-huang and cola nut. This combination was recently banned by the FDA in a new ruling that outlawed all products containing a combination of caffeine and ephedrine, stating that they can cause “severe injury or death in some people who consume them.”

We should be mindful of a range of possible impairments in performance that may counterbalance the possible improvements in output that may be obtained with caffeine. By increasing digestive secretions, caffeine may cause stomach discomfort and thereby impede performance. And perhaps more important, because caffeine is a diuretic, it may promote excess urination, which in turn could lead to dehydration, one of the primary problems for athletes, especially endurance athletes, because the fatigue experienced as a result of dehydration is indistinguishable from the normal fatigue of hard training. Excessive urination can also cause a loss of vitamins and minerals essential to peak athletic performance, although it must be noted that some studies have found no effect from caffeine on either fluid balance or thermoregulation during exercise. In light of such considerations, however, athletes should be mindful of the possibility that intestinal problems or dehydration might create an acute disadvantage in the middle of an athletic event which more than offsets any earlier advantage.