What can I sip instead of coffee to feel full without gaining weight?

I want to eat but I do not want to gain weight, and I used to buy an extra large coffee from McDonalds when I had this issue so I could spend 2 hours sipping it and feeling like I had food in my mouth without eating food and gaining weight, but now I am told that caffeine depletes your vitamin B so I want an alternative to coffee.

What can I sip instead of coffee to feel full without gaining weight?
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