(HealthScoutNews) -- Halloween candy. Thanksgiving turkey. Christmas cookies. New Year's Eve celebrations.

Many Americans once again spent the long holiday season indulging their appetites, and the result is that the nation is becoming one vast waistland.

Need official confirmation? The U.S. Surgeon General declared last month that 61 percent of adult Americans -- almost two in three -- are overweight.

But the new year offers a chance to start fresh. And if one of your resolutions is to lose weight, the best way to do it is slow and steady.

"There aren't any terrific magic bullets," says Johanna T. Dwyer, the director of the Frances Stern Nutrition Center at Tufts University. "A modest caloric decrease and increased activity are the keys."

Losing weight can make you feel better about your appearance and more comfortable in your clothes. But the best reason to lose weight may be for your health.

Obesity is closing in on smoking as the nation's No. 1 public health enemy. As many as 300,000 deaths annually are linked to excess weight, and some studies have estimated the cost to society at more than $100 billion a year.

Consider these statistics:

• Overweight people have double the risk of high blood pressure compared to those of normal weight.

• They also have two to three times the risk of a heart attack, double the risk of stroke and up to four times the risk of diabetes.

• They have two to three times the risk of developing gallstones, double the risk of getting colon cancer and at least double the risk of developing arthritis in their knees.

• Overall, people who are overweight have a 50 percent to 100 percent higher risk of death from all causes than those who are of normal weight.

Losing even one pound a year, over several years, can dramatically improve your health. For example, one study found that people who lost a pound a year for eight years cut their risk of diabetes by between 37 percent and 62 percent.

To lose a pound a year, all you need to do is cut out 10 calories a day -- less than the amount in a couple of potato chips.

But dieting alone isn't the way to better health; exercise needs to be part of the picture.

"We're very sedentary," Dwyer says. "We're couch potatoes. And so it's important to remember that the solutions to obesity are not all through diet alone. It also requires a focus on physical activity."

Your options for exercise are limited only by your imagination. You can run, swim, bike, climb rocks, climb stairs -- even climb mountain trails.

But experts say the best way to start is by walking, a simple activity everyone can do that requires no special equipment. The Surgeon General recommends that every American get 150 minutes of moderate exercise -- such as walking -- each week.

"We're not talking about going out and being a marathon runner and killing yourself," says Linda G. Snetselaar, head of preventive nutrition education at the University of Iowa's College of Public Health. "We're talking about going out and walking 30 minutes."

"If you can walk for 150 minutes a week -- that's 30 minutes a day, five days a week -- you can make a marked difference in your health," she says.

People who do get that amount of exercise can cut their risk of heart disease in half, studies have shown. One study found that 30 minutes of daily exercise is just as effective against depression as anti-depressive drugs.

If you can combine walking and weightlifting, you should do even better. By replacing fat with muscle, you burn more calories. A recent study found that women who lifted weights for 40 minutes continued to burn an extra 155 calories in the two hours after they stopped exercising.

And if you're over 30, or you haven't exercised regularly in recent years, you should consult your doctor before beginning an exercise program.

Just don't expect instant results. Remember, it took a long time to get out of shape -- you won't get back into shape overnight.

"People often get discouraged," says Snetselaar. "They think that if they can't lose 30 pounds in a week, they've failed and they're not going to do it any more."

Over the long haul, experts say, the United States will have to mobilize against fat the way it did against smoking 35 years ago.

Planners should design parks with walking and hiking trails that are easily accessible. Towns and cities need to be more pedestrian-friendly, so cars aren't required for even the simplest errands, health experts say.

And schools should bring back mandatory physical education -- and stop allowing sodas and fatty fast food to be sold in school cafeterias.

"This is bigger than the medical community," says Dwyer. "It's an environmental thing, it's a lifestyle thing. Everyone needs to be involved."

What to Do: Find out if you're overweight by using this body mass index calculator from the National Heart, Lung and Blood Institute. And check out the health risks of obesity at this National Institutes of Health Web site.

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