In the decaffeinated group, DIT was 6 percent, but in the caffeinated, 9 percent. Blood tests revealed that coffee drinkers started burning more fat, instead of carbohydrate, sooner than decaf drinkers. An increase from 6 percent to 9 percent isn’t bad—and possibly, the effect would be greater still after a more thermogenic meal. Importantly, this effect is additive to the effects of caffeine on metabolic rate. Other benefits of caffeine include appetite suppression, improved exercise performance, better insulin sensitivity and increased muscle glycogen synthesis (ref. 19,23,24,25).
