Single-dose oral administration of 100 mg caffeine increased the resting metabolic
rate of both lean and postobese human volunteers by 3-4% (p < 0.02) over 150 mm
and improved the defective diet-induced thermogenesis observed in the postobese subjects.
Measurements of energy expenditure (EE) in a room respirometer indicate that repeated
caffeine administration (100 mg) at 2-h intervals over a 12-h day period increased the EE of
both subject groups by 8-1 1% (p < 0.01) during that period but had no influence on the subsequent
12-h night EE. The net effect was a significant increase (p < 0.02) in daily EE of 150
kcal in the lean volunteers and 79 kcal in the postobese subjects. Caffeine at commonly consumed
doses can have a significant influence on energy balance and may promote thermogenesis
in the treatment ofobesity.