Some people deride them as “sugar water,” others as “liquid candy.” Never favorites with dietitians or parents, sodas are receiving more and more nutritional heat these days – and the drumbeat to run them out of schools is growing louder.

Legislation is on the march, with anti-soda measures under consideration in many states and school districts.

The American Beverage Assn., which represents most U.S. soft drink suppliers, is offering some concessions about school concessions. At an August meeting and in full-page ads in major newspapers, it resolved to remove sodas entirely from elementary schools, allow middle-school students access to full-calorie sodas and fruit drinks only after school hours, and ensure that no more than 50 percent of the vending machine beverage offerings in high schools are soft drinks.

Why all this finger-pointing at sodas? After all, we live in an environment brimming with burgers, fries, snack cakes and chips, dealt in heftier and heftier portions to children slumped in front of televisions and computers. What earthly effect can limiting just one item – the beverage – have on the health and weight of our offspring?

Nutrition scientists agree that getting children to move more and eat better are important. But they also say that this spotlight on sugary soft drinks makes sense. These drinks are our No. 1 dietary source of added sugars, they say. Studies connect them to body heft and nutrient shortfalls. And that moniker “liquid candy” is spot-on: The drinks are pretty much bereft of nutritional value.

“If you have to cut calories . . . why not start with sugar water?” says Dr. Carlos Camargo, associate professor of medicine at Harvard Medical School.

But don’t just focus on sodas, experts add.

Juice drinks, sports drinks, energy drinks, calorie-laden coffee and even juice itself will help pack on pounds if imbibed to excess – and more than artificially sweetened sodas will.

The American Academy of Pediatrics recommends that school-age children limit their fruit juice to 8 to 12 ounces daily.

Electrolyte-replenishing sports drinks, which in the plan would remain in middle and high schools, are useful after very vigorous exercise but hardly needed after a 30-minute P.E. session.

“There’s sort of a misperception about the role that sports drinks play in a nutritious diet,” says Rachel Johnson, professor of nutrition at the University of Vermont. “If a child’s thirsty, water is the best beverage.”

Americans got their first taste of carbonated beverages well over a century ago. The first bottled sodas were produced in the 1830s, sold in corked bottles and often jazzed up with flavors such as sarsaparilla, lemon and strawberry.

The industry took off in 1892 after the invention of a cap to keep gas firmly in bottles, allowing for wide distribution.

By 1976, soft drink sales had surpassed those of milk. Since 1971, soda consumption has doubled, from an average of 25.5 gallons per person per year to more than 46 gallons in 2003.

Most of these gallons, especially among children, are full-calorie, although in recent years there has been a small, steady increase in diet soda sales.

At the same time, a plethora of other, non-fizzy sugar-sweetened drinks have gained popularity, especially among the young: trendy teas, energy drinks and sports drinks.

In 2002, a report from the federally mandated Institute of Medicine found that people consuming lots of added sugars were more likely to be deficient in micronutrients such as calcium, phosphorus and magnesium, as well as various vitamins.

On the basis of these nutrient deficiencies, the panel recommended that we limit our added sugar intake to no more than 25 percent of our daily calories.

Another cautionary note against sugar was sounded earlier this year in the 2005 Dietary Guidelines for Americans, which guides federal nutrition education and school lunches.

Members of the committee acknowledged that good studies linking soft drinks and excess heft are few, and the relationships when found are sometimes weak, says committee member Joanne Lupton, professor of nutrition at Texas A&M University.

Still, the committee felt there was enough evidence to suggest people lower their added sugar intake, especially from sugar-sweetened beverages, she says.