A recent study featured 12 young men, average age 26. In the first part they took a capsule containing ingredients equivalent to 3 1/2 cups of green tea three times a day, the last one hour before exercise. Other subjects got a placebo containing corn flour. The exercise consisted of 30 minutes of cycling at an intensity equal to 60 percent of maximum heart rate. In the second part of the study 11 of the men took an oral glucose-tolerance test before and after taking green tea capsules.

Those who took the green tea capsules had a 17 percent greater contribution of fat to energy expenditure during exercise than those who took the placebo. That scale of fat oxidation was over and above what usually occurs during exercise, pointing to a definite green tea effect. The second part of the study showed that green tea increased insulin sensitivity by 13 percent, which reduced the insulin response to a glucose load by 15 percent.

Another study, this one with isolated fat cells, found that green tea can inhibit the development of new fat cells. The mechanism is an inhibition of GPDH, an enzyme, along with the inhibition of PPAR-gamma, a protein that boosts bodyfat. Green tea acts as an oxidant in fat cells—but that’s good because it activates AMPK, a protein that stimulates fat oxidation in muscle during exercise.

Application: Drink green tea for health and to get leaner and/or take a green tea supplement three times a day to augment fat burning.