Time for coffee and tea
Coffee nutritional facts: Coffee drinking and weight loss
Coffee is one of the top five commodity exports moving through world trade channels, an indication of its widespread use. Almost every other person you meet is probably a coffee drinker. We drink coffee to wake us up in the morning and to carry us through most of our day.
Recent research has shown, however, that consumption of coffee and caffeine (there are other non-coffee drinks that contain caffeine, such as tea and coke) does more than wake you up — it can help you lose weight.
Much of the research activity looked into the relationship of coffee weight loss and caffeine consumption to diabetes, and many of the studies found evidence that coffee consumption can reduce the risk of type-2 diabetes, improve normal metabolism of glucose, or both. The Tea diabetes and green tea weight loss relationships are explored in another article.
The coffee research, however, found that consumption of ground caffeinated coffee appeared to have an independent relationship with weight loss. The findings implied that the caffeine present in coffee may help people to decrease body weight.
This suggestion finds some support from the results of a recent, larger study over a 12-year period, which determined that those who increased their consumption of caffeine or caffeinated coffee were less likely to gain weight. The weight loss measured was relatively modest, but the correlation was well established.
Experiments on long-term consumption of caffeine, caffeinated tea and caffeinated cola decreased the body weight in rodents, which gave rise to the supposition that the same thing would happen in humans. There is now considerable evidence in many studies in humans indicating that coffee contributes to weight loss in humans by increasing thermogenesis.
Thermogenesis is the generation or production of body heat. This happens in three ways: through exercise, through our own sympathetic nervous system which regulates body temperature, and through our diet, when food is converted to heat. Thermogenesis is a way for the body to burn up the excess, un-needed calories.
The studies estimate that habitual consumption of six cups of coffee (or about 600 milligrams caffeine per day) resulted in increased expenditure of 100 kilocalories per day, which would indeed result in significantly lower weight. This rate is not true for all types of coffee; it seems that only caffeinated coffee (whether ground or instant) does the job. The accumulated evidence points to caffeine as the primary ingredient in coffee that produces its thermogenic effect, and that drinking coffee for weight loss may have a positive impact on ones diet.
Further investigation showed that coffee induces thermogenesis in part by increasing the oxidation — or shall we say, burning up — of fat. With more burnt fat, individuals would then lose weight.
The link between caffeine, thermogenesis, and resultant weight loss is clear. The specific biological mechanism by which caffeine produces these effects is not yet fully known. The experiments so far indicate that, in large part, the thermogenic effect of caffeine may be due to increased heart rate and increased production of lactate and triacylglycerol. It may be years before we get a clear understanding of the mechanisms.
For now, given the above facts, we can say with assurance that the caffeine in your coffee (and tea) can help you lose weight.
Reference. : Greenberg et al, Coffee, diabetes, and weight control, Am J Clin Nutr 2006;84:682–93.