A cup of black coffee an hour before exercising can help with weight loss.
The caffeine stimulates sympathetic nerves in the body and hence increases cortisol secretion, which resolves fat and turns it into energy.
Park Hyon of the College of Physical Education at Kyunghee University said, "It takes about 40 to 60 minutes for caffeine to be absorbed in the body. The effect doesn’t kick in immediately."
The amount of caffeine does not affect how well fat is resolved. Kim Tae-wook, who teaches at the KBS Sports Academy, said about 3 mg of caffeine is adequate per kg of your weight.
According to a 2012 survey by the Ministry of Food and Drug Safety, one cup of regular-sized Americano contains an average of 124 mg of caffeine.
Despite the benefits, too much coffee is bad for you. Sunwoo Sung of the Asan Medical Center at the University of Ulsan said, "Some side effects of excessive caffeine intake, that's to say over the recommended 400 mg daily, include cardiac arrest, insomnia, and heartburn."
For the same reason, other drinks containing high levels of caffeine are not good for weight loss.