MICHELE NORRIS, Host:

To take a closer look at the drinks that will be allowed in schools under this plan, diet sodas, sports drinks and certain kinds of juice, we turn to Dr. Madelyne Fernstrom. She's director of the Weight Management Center of the University of Pittsburgh Medical Center. Dr. Fernstrom, so glad you could help us out here. Thanks so much.

MADELYN FERNSTROM: Oh you're welcome. Nice to talk to you.

NORRIS: Now let's look first at fruit juice. Is juice a healthier alternative?

FERNSTROM: Juice is not a healthy alternative, because you always want to eat your fruit and not drink it. You get a lot of wasted calories and a lot of fluid, but you can just drink water or something without calories.

NORRIS: But for the students who are in these schools, water's probably not an option. They're going to be looking at soda or juice. So if they're going to choose juices, are all juices equal? Are some juices better than others?

FERNSTROM: You want to get 100 percent fruit juice if you're going to go that route. There's really no reason why you can't have an option of naturally sweetened flavored waters along with some juices that are actually reduced calorie juices that have just much less sugar in them. That'd be another option. Because the issue is you're not always getting juice, you're getting a lot of added sweeteners, high fructose corn syrup and added sugar that add calories and no nutritional value.

NORRIS: So it's the case where you have to look for the label and look for corn syrup as an ingredient and also look for sort of nutritional cues. If they're using words like cocktail and beverage instead of juice.

FERNSTROM: Right, exactly. When you look for 100 percent fruit juice, you also want to look for the word fortified, because it'll often be fortified with vitamins and minerals, and most importantly, there are a lot of juices now that have some calcium added. Very important for growing bones and strong teeth.

NORRIS: Now is there a case also, where we might not be able to see this in a vending machine, but you should actually look at the juice. If it's cloudy it means one thing, if it's very clear that means something else.

FERNSTROM: Well, you know, there are many juices that will have sort of juice pieces and it might look a little cloudy or fragments settled to the bottom. This is a good thing because it's got more fruit pulp in it. Clear juices don't make it better. It doesn't make it more pure. It doesn't make it more like water.

NORRIS: What about sports drinks?

FERNSTROM: Sports drinks are typically for someone that's having a burst of activity of two or three hours of exercise. The every day running around individuals don't need to have the calories that are in sports beverages nor any of the vitamins or minerals. If you do like that taste, there are these products available that are light versions that have just a tiny bit of sugar for a little bit of energy, but not all the extra oomph that most people don't need.

NORRIS: What about diet soda? They're low in calories, low in sugar. They'll also be allowed. Are those good for kids? Better alternative?

FERNSTROM: You know what? They're a better alternative for kids who want to drink soda. If you have a child who won't drink water, who doesn't like skim milk, then that's going to be most important.

NORRIS: What's the best choice here?

FERNSTROM: The best choice here is going to be something without a lot of added calories, because the hidden calories in fluids are really a problem in the increasing obesity in children and adolescents. What you do want to look for is a variety of bottled waters, of low-calorie flavored waters that are going to give the oomph of something juice-like, but not the extra calories.

NORRIS: Dr. Fernstrom, thanks so much.

FERNSTROM: You're welcome.

NORRIS: Dr. Madelyn Fernstrom is the director of the Weight Management Center at the University of Pittsburgh. Transcript provided by NPR, Copyright NPR.