does caffeine make person gain weight?

Answer 1

No, it does not and cannot. The primary reason why it doesn't is because caffeine contains no energy. It has no calories. You can't create fat out of no energy. What it does, however, is actually act as an appetite suppressant due to how it interacts with your body. So in many ways, it will actually assist a person in losing weight, not gaining!

Answer 2

If anything, caffeine itself raises metabolism and makes one lose weight.

The only problem is that caffeine usually comes in soda, coffee, chocolate, etc. And these (when coffee is sweetened with sugars or creamers) cause people to gain weight when not consumed in moderation.