Step right up, folks, for the latest sure-fire weight-loss scheme. It’s four simple words, easy to remember and free: Eat less, move more.

First, the math: Figure how many calories you need each day to maintain your equilibrium. For most people, that’s around 2,000. Then balance your diet: Limit total fat to less than 65 grams a day, saturated fat to 20 grams, cholesterol to 300 milligrams, and so forth.

But Americans, by and large, haven’t embraced the equation. In the meantime, we’ve become the biggest people on the planet.

Alarmed public officials, citing statistics that indicate at least 400,000 Americans a year die because of health problems associated with being fat, say the nation is suffering an obesity epidemic that is approaching smoking as the country’s leading cause of preventable death.

Over three decades, Diane Truax of Sacramento, Calif., has been getting plenty of exercise as a door-to-door saleswoman for Avon, but six years ago she nonetheless was a walking case study of the kinds of health problems linked to excessive weight.

She weighed 300 pounds and was suffering chest pains. Her doctor found nothing wrong with her heart, though her blood pressure was high and she had diabetes.

“I decided I didn’t want to die. I decided to lose weight.”

Now, she’s 110 pounds lighter and no longer takes medication for blood pressure or diabetes.

“It’s been difficult to keep it off, so I watch what I eat and I exercise,” Truax says. “I eat half of what I used to eat. … I didn’t join any program. I didn’t need to pay anyone to know how to lose weight. I knew what I had to do.”

As president of Shape Up America, Barbara Moore of Portage, Wis., has been trying to raise public awareness of obesity as a health issue for the past decade, since former Surgeon General Dr. C. Everett Koop founded the group in 1994.

“It’s still an uphill battle. People don’t seem to view the problem as a health problem, they view it as a cosmetic problem,” Moore says.

Numerous factors contribute to the country’s collective weight gain, she notes:

¢ Technological developments in home and workplace over the past century.

¢ Elimination of physical education classes and the reluctance of parents to let children roam free after school.

¢ The abundance of rich and affordable food.

¢ Abandonment of home economics courses in school curricula.

It isn’t easy, agree nutritionists and people who have whittled off pounds and kept them off, but it can be done with a mix of strategies blended with personal gumption.

Almost invariably, weight control involves tracking calories, though not necessarily a precise meal-by-meal accounting to assure that the daily total doesn’t exceed the customary 1,600 to 2,800 needed by most adults.

The National Weight Control Registry, a continuing research project tracks nearly 3,000 people who have lost at least 30 pounds. The average participant has shed 65 pounds and kept it off five years, Hensrud says.

The registry has uncovered three pivotal patterns among its participants:

¢ They exercise, burning an average 400 calories a day in physical activity, the equivalent of about an hour of brisk walking.

¢ They follow lower-fat diets, cut back on sugar and sweets and eat more fruits and vegetables than are commonly consumed in the American diet.

¢ They eat about 1,400 calories a day, a lot less than the typical American total.