It's time for state governments to take tough action to cut down their young citizens' sugar and fat intake. For the kids' sake — and the states' sake.

Latest evidence: just-released data that America's alarming obesity rates — sure precursors of more diabetes, hypertension, heart failure and cancer — are continuing to climb in 49 of the 50 states.

The advocacy group Trust for America's Health is reporting, based on data from the Centers for Disease Control and Prevention, that the percentage of obese Americans has zoomed to 22.7 percent, up 1.5 points since early in the decade. Topping the list — with adult-obesity rates of 27 percent or more — are Mississippi, Alabama, West Virginia, Louisiana and Tennessee. Only Oregon, at 21 percent, reports no recent increase.

But depressingly few states are stepping up to take assertive action to fight obesity where they have the most power — in the public schools. Only six states have set nutritional standards for school lunches and snacks more strict than the existing, loose requirements of the U.S. Department of Agriculture. Only 11 have set standards for permissible calories or quality in soft drinks or other foods sold in school snack shops or vending machines.

And up to now, only four states test students' BMI (body mass index) figures — even though a first report, from Arkansas, found 40 percent of students either overweight or in clear risk of becoming overweight.

Except for inertia, what is it that's delaying states and school districts in taking action to combat the obesity levels that not only darken life prospects for their citizens but also add perilously to present and future state-paid medical costs?

The big junk-food lobby — that's what. Nutrition advocates have been focusing in on soda pop — drinks loaded with sugars, mostly high-fructose corn syrup, that not only add hundreds of calories to teens' diets but also displace milk and fruit juices and their essential vitamins and minerals.

The "liquid candy" of soda pop, reports the Center for Science in the Public Interest, is today providing the average 12- to 19-year-old boy with about 15 teaspoons of refined sugar a day, the average girl 10 teaspoons — amounts roughly equal to the federal government's limits of teens' sugar consumption from all foods.

But the carbonated soft-drink lobby — the Coca-Colas and Pepsis and like firms — have been lobbying heavily to choke off restrictions on the selling of sodas in vending machines and cafeterias in the nation's public schools.

In June, Connecticut Gov. Jodi Rell, a Republican, vetoed what would have been the nation's strongest school-based nutrition law, written to allow only water, juice and milk to be sold during the school day.

In Kentucky, nutrition advocates were worn down battling Coca-Cola lobbyists for four years and could only pass a compromise bill banning soda in elementary — but not middle or high — schools. Supporters of Arizona legislation managed to get a soft-drink ban through eighth grade, but not high school. Strong legislation in Oregon would have banned carbonated soft drinks, candy and fried-pastry products in schools, but it was gutted after intense lobbying by the Oregon Soft Drink Association.

In a purported move to provide lower-calorie drinks in schools, the American Beverage Association, lobbying arm of the industry, recently endorsed new guidelines to cut off sodas in elementary schools, allow lower-calorie beverages in middle schools, and permit all varieties, full-calorie pop included, in high schools.

Asserts public-health attorney Michele Simon, such school districts as Los Angeles, San Francisco, Boston, Seattle, Chicago and Philadelphia have already banned all sodas — so why not apply the ban everywhere?

One reason: Vending machines dispensing sodas without nutritional value have become a lucrative source of cash for many schools. School districts become junk-food pushers. States shouldn't interfere, say defenders, citing local home rule.

The argument is a smoke screen. A generation of more obese kids coming out of the schools will spell big trouble later. Smart state governments will give the schools the extra money they need for phys ed and extracurricular activities now. Then they'll ban all soda pop in the schools — saving themselves (and their taxpayers) a real bundle in Medicaid and other health outlays later.

But first, they'll need the gumption to tell the soda lobby to get out of the way.