The Senate’s Majority Leader and top doctor calls obesity a “growing epidemic,” “a major national health crisis” and “a plague.” But what is Congress doing about it? Not much.

In a Nov. 21 floor speech, Majority Leader/heart surgeon Bill Frist (R-Tenn.) called on Senators to support a $60 million bill funding demonstration projects in health and fitness education, but Congress is nowhere near doing what it ought to: tax fat. And sugar, too.

[IMGCAP(1)] A hefty tax based on the fat and sugar content of foods would discourage consumption, provide revenue for school programs (including physical education) and recover some of the billions that obesity-related illnesses cost the government in Medicare and Medicaid outlays.

Taxing fat and sugar in fast foods and snacks is a far better way to fight obesity than allowing trial lawyers to get rich suing McDonald’s, Wendy’s and Burger King. The government can make far better use of the money than lawyers.

Having made billions suing tobacco and asbestos companies, trial lawyers have set their sights on fast-food chains — leading House Republicans to promote legislation to bar them from doing so.

There is a good case for eventually passing the so-called Personal Responsibility in Food Consumption Act, but before protecting the merchants of fat from lawsuits, Congress should do what it can to encourage — or require — them to help fight obesity.

At the moment, as George Washington University law professor John Banzhaf has pointed out, the threat of lawsuits has caused McDonald’s, among other chains, to provide some nutritional information to customers and to offer more non-fattening foods in its restaurants.

Backers of the “Personal Responsibility” bill, including the National Restaurant Association and its front group, the Center for Consumer Freedom, maintain that people know what they’re getting into when they order a Big Mac, a super-sized order of fries and a chocolate sundae.

Well, they do. But fatness is not just an individual problem. As Frist said, it’s a national problem that’s getting worse every year.

“Sixty percent of Americans today are overweight,” he said. “There are 300,000 deaths a year that can be directly attributed to fat.” And the percentage of children who are overweight has quadrupled since the 1960s.

Unless trends change, Frist said, “one in three Americans born in the year 2000 will develop diabetes in their lifetime” and the rate will one in two for African-Americans and Hispanics.

People suffering from diabetes can go blind, experience kidney failure and lose limbs because of poor circulation.

A 2001 surgeon general’s report estimated that the annual cost of treating obesity-related illnesses — heart disease, high blood pressure and diabetes — is $117 billion a year.

So it behooves the government to do something about the crisis. The Food and Drug Administration announced this summer that it will require food labels to list trans-fatty acids, and Commissioner Mark McClellan has announced a study of other measures the FDA might take.

The FDA probably needs legislation from Congress to require that fast food restaurants list the calorie and fat content of their fare on their menus or at the ordering counter.

There’s probably no way to legislate this, but federal officials surely could encourage private insurance companies to charge a higher premium for people who are overweight than they do for those who aren’t — much as they do for smokers.

And, they could cheer on airlines when they contemplate charging double fares to passengers who are so fat that they can’t fit into a single seat. Southwest Airlines considered such a step, but backed down under public pressure.

Other steps Congress could take include giving states an incentive to restore physical education programs to their schools and institute other anti-obesity programs such as the “weight report cards” instituted in Arkansas and the ban on soda machines being considered in Maine.

Fiscal crises have forced some school districts to install vending machines containing snacks and sodas as money-raising devices. The federal government ought to subsidize banning them.

The bill Frist recommended, the Improved Nutrition and Physical Activity Act, does authorize the government to examine whether food aid programs for the poor, including school lunches, contribute to health or obesity.

IMPACT also adds obesity as a priority condition to be addressed in federal training programs for health professionals, but mainly it creates a fund for local demonstration projects and an evaluation system to see what works.

That’s all to the good. But a real attack on obesity requires making people pay — both those who serve up fatty foods and those who consume them to excess.