When I lost weight many years ago, I heard that drinking black coffee was very effective. Then I went to drink it. It was really diuretic. Moreover, I have just drunk it for a while, and I feel particularly refreshed after drinking it. The more you drink, the more you drink, 3-4 cups a day. Finally, a very strange phenomenon appeared. I'm sleepy immediately after drinking black coffee! And I still couldn't open my eyes, and then I consulted some coffee experts, who said I overdosed. Maybe it's caffeine allergy. So you can drink black coffee, but you can't overdo it.