It is scientific?

[flytothesky]

Hello~ Would you help me with saying this naturally please?

A: If you take this neck glass for several days, you will lose your wait.

B: sure? It is scientific?

A: No, can’t prove scientifically but it is. You’d better buy one.

B: Something small fish. I’m not going to buy it.

[Soup]

A: If you take this, you will lose weight quickly.

B: Says who? Has it been scientifically proven?

A: No, I can’t prove it scientifically, but it works. You should buy one.

B: Sounds fishy. I’m not going to buy it.