1. It takes 3500 calories to make a pound of fat. It does not matter where these calories come from. They still add up.
    
2. If you presently drink fruit juice, sodas, and/or sports drinks, note the calorie count on the labels. Keep a log for one week. Add up the calories, and divide the total by 3500. This is how many pounds of fat you will lose each week by not drinking this stuff.

More about these drinks

1. Fruit juice, sodas, and sports drinks are all concentrated sources of calories. Many people fail to account for these beverages, and then wonder why they are fat despite "doing everything right."
    
2. Sodas are simply not fit for human consumption. See this article on why softdrinks are unsafe.
    
3. Fruit juices "seem healthy," but they are basically the fruit with the fiber missing. That fiber is an important nutrient. Eating whole fruit is infinitely better for you than drinking the juice only. Don't drink fruit juice unless you have just gotten up, just worked out, or have some health issue that requires you to drink it (that does not include the flatulent, fraudulent claims that calcium-enriched orange juice fights off osteoporosis--it actually increases the risk).
    
4. Sports drinks are totally unnecessary for the typical "athlete." People who burn up maybe 150 calories exercising improperly (and without focus) at the gym guzzle down 800 calories of sports drink and then wonder why they are getting fatter. Climbers, long-distance runners, and cyclists can use sports drinks. A climber can burn 10,000 calories in one day. But that is high-end, elite activity--not anywhere near the norm of the average person hiking or spending an hour at the gym.

Some other points to keep in mind

1. Yes, it does matter what you eat--but not in the manner fad diets lead people to believe. You cannot get away from total calories--that is, how much you eat.
    
2. Counting carbs, calories, or points is a fool's errand. It does not work for a long list of reasons.
    
3. The key to right-sizing your body is right-sizing your portions. That includes everything you drink, not just what you eat.