If illegal stimulants cause weight loss, what about high doses of caffeine?

I know that drugs like cocaine and methamphetamine, and even legal rx drugs like adderall and ritalin cause weight loss because they are stimulants and suppress appetite. Well, caffeine is a stimulant, and I notice that after a few shots of espresso I am not very hungry. Can high does of caffeine have a weight loss effect? If so, how much must one take?