You know what I have noticed? After drinking way too much for years, I have discovered if someone discovers you drink a lot of Coca-Cola or other sugary soda's, the reactions usually go after a set pattern.
"It's not healthy you know." Most common one. Yes, it isn't healthy. But mostly everyone knows that sugary sodas aren't healthy for you. And this one is often said in a low, clear but steady voice. People also say it like they think you aren't aware of that fact.
"You'll gain weight." It is the nasty brother of the first question.Said very condescendingly. Alternatively, you might also get told that it is the reason why you are fat.
The diabetes scare. This is where the person will tell horror stories about diabetes and that you are sure to get it. If you also happen to fear needles, this is where said person will use that against you.
"But what about your teeth!" This one is usually uttered by people who are trying to find even more reasons why you shouldn't drink soda. Also by dentists or people who often has had holes in their teeth.
All of these, with the exception of the second one isn't illegitimate concerns, what the issue is how they are used to convince you to stop drinking soda. The tone of voice is actually pretty important here. Many use these starements as a means of concern-mongering, especially if you are calling them out. Even medical personnel might use all of these against you. My dentist, whom one would think was going to use number four used number two when she saw me drinking one just before entering their office. (Yes, I know, it was a bad idea to drink soda before the appointment.) And it doesn't mean my dentist or anyone else has the right to use these statements against me or anyone else who drinks too much soda.