Doesn't matter what you eat, just how much of it. One glass of soda a day will do nothing to you IF you get sufficient exercise.
People that say "I have super fast metabolism hurr hurr I can eats whatever I wants lol~" are so full of shit. You are NOT some kind of super-human being with a genetically superior body. You have the EXACT same internal organs as other people, you just live a different LIFE.
Look at the calorie count before you eat something; but wait! Also look at the servings per container. You might see "150 calories" and think oh, no big deal. But then it'll say something like, 4 serving per container next to it. Which of course means if you drink that whole can, it'll be SIX HUNDRED (600) calories. THAT'S AN ENTIRE DINNER WORTH OF CALORIES. IN A DRINK.
I burn like 1200 calories a day at my job. I WORK MY ASS OFF. So I can drink TWO glasses of soda a day if I want without gaining ANY weight.
However... if you're an unemployed individual, and you play games all day. Two glasses of soda is like having an extra meal worth of fat. However... soda doesn't fill you up. In fact, it makes you thirsty as it's a diuretic. So often times, people will CHUG it.
So I agree, soft drinks are one of the worst things you can put in your body, because they are
1) Highly addictive
2) Delicious
3) Extremely, extremely fattening
Start looking at what you eat (based on a 2000 calorie diet a day) and you might just see yourself reaching 2000 calories before you even made it to lunch time. This means its time for a change.... or time to see yourself continue to gain.
I hope I don't come off as some snobby vegan or something, I'm in fact struggling with losing weight myself, I learned this stuff the hard way.
However... its working. I've lost 40 pounds this year, and I hope to lose another 40 at least.