The U.S. population is growing, and so is the individual American. And don't look for relief from the crush anytime soon: Sixty-three percent of men and 55 percent of women over the age of 25 are overweight, say researchers at Tufts University in Boston, and nearly one-quarter are obese (that means they're at least 30 percent over their ideal weight). Our national weight problem is quickly reaching Pillsbury Doughboy proportions.

"It really is an epidemic," maintains obesity expert James O. Hill, Ph.D., director of the Center for Human Nutrition at the University of Colorado Health Science Center in Denver. "If being overweight were an infectious disease, we would have mobilized the country. We would have declared a state of emergency."

We can place the blame for this swollen state of affairs on our convenience-minded culture, Hill says. We have gotten so sedentary that many of us leave our sofas only to get another helping of something tasty--usually with the extra fat and sugar the food industry promotes so aggressively. Researchers blame the resulting calorie imbalance for most of our weight increase.

Beginning in the 1980s, according to the journal Science, the accouterments of modernization--including computers, remote controls, multiple car ownership, more escalators and shuttles--combined with an unprecedented abundance of cheap food to produce a population that moves less and eats more. "Except for the fortunate few people who are not going to gain weight no matter what they do, you can't live life today in our society and maintain a normal weight," Hill says. "The environment is going to get you."

It takes determination to stare down a culture that wants you to be quiet, sit down and eat. To maintain your resolve, it helps to know how the food industry manipulates and profits from your cravings and how the society at large discourages an active lifestyle. Here are the ways your environment makes you fat--and how to fight back. Knowledge, after all, is power. --M.E.S.

Why we've stopped moving

The year is 1880 -- think "Little House on the Prairie" -- and you want ice cream. Sometime last winter, you took your horse and wagon to the local lake and spent a day harvesting blocks of ice. You hauled them to the icehouse and stored them under sawdust. Now you dust off the ice, shave off some chips and add them to the ice-cream churn with salt and the cream mixture you made after milking your beloved Bessie. You start turning the crank on the churn. Your arms begin to burn. You churn and churn some more. Finally, you have your ice cream. Fast-forward to today. Craving your Haagen-Dazs fix? "You just get in your car and drive to the grocery store and buy a half-gallon," says Barbara J. Moore, Ph.D., president of ShapeUp America! Then you plunk yourself down on the couch, remote control handy, and eat half the tub.

Big and bigger

Forget about Generation X. We're well on our way to becoming Generation XL. Advances in technology have engineered the effort out of just about everything. We drive to the office, sit in front of the computer for hours, order in food and drive to the corner convenience store to buy a newspaper. We barely need to lift a finger, much less a 50-pound block of ice. "There are even remote-controlled fireplaces!" Hill exclaims.

And if we aren't yet so lazy that we order all of our food and services online, many of us can now do all our errands in one superstore. "And, then, people drive around for 10 minutes to get a parking place near the door," marvels James Anderson, M.D., an obesity expert at the University of Kentucky at Lexington.

Those of you about to stop reading because you log your five times a week on the stairclimber aren't off the hook. The U.S. Centers for Disease Control and Prevention (CDC) say that only 10 percent of adults get enough physical activity from workouts, which means that even an hour at the gym may not be enough to stave off extra pounds.

That's because our remote controls, computer mice and automobiles--even the power steering and power windows in our cars--are saving us far too many calories. Think about it: If you drive to work instead of taking a train and eliminate a 10-minute walk to the station each way, you burn about 90 fewer calories per day, which could add about 6 pounds of body fat over a 10-year period. Use a portable phone, which means you don't have to run to answer calls, and you can tack on another two to three pounds a year, calculates Patricia Eisenman, Ph.D., chairwoman of the department of exercise and sport science at the University of Utah in Salt Lake City.

Steven N. Blair, P.E.D., senior scientific editor of the U.S. Surgeon General's 1996 Report on Physical Activity, estimates that we are expending about 800 fewer calories per day--think two slices of New York-style cheesecake--than our parents did. So even if you are running six miles a day, that's only about 600-700 calories you have kissed goodbye. The extra 100-200 calories a day you haven't burned may translate to an extra 10-20 pounds a year.

An immovable force

In our defense, it's almost as if the culture wants us to be fat. The pressure to be inactive starts early. Less than one-third of kids who live within a mile of school get there on foot, while recess and high-quality physical education have become relics of the good old days. When PE classes are provided, they're often led by untrained teachers and seldom involve much vigorous activity. Worse, some don't focus on the fun of movement or teach children fundamental physical skills.

Many of us, children and adults, also are spending more time watching television and videos or playing electronic and computer games. One study found that a teenager's obesity risk increased 2 percent for every additional hour spent in front of the TV. More than ever, we are passive, sedentary observers of our culture's entertainment.

And new suburban communities are often designed without sidewalks or crosswalks, says William Dietz, M.D., Ph.D., director of the CDC's Division of Nutrition and Physical Activity. To run an errand, residents are forced to drive instead of walking a few blocks. "The infrastructure of cities supports physical activity--there are sidewalks, stoplights and places to walk to," says Dietz. "But new suburban cul-de-sac communities have strip malls, so people drive everywhere, even though one quarter of all trips are less than a mile."

We're all in this together

While obesity rates are inching up around the world--from 8 percent to 13 percent in Australia and Brazil, for example--only in America are they skyrocketing. Perhaps people in other countries are staying slimmer because their gas prices are higher or it's a tradition to walk to the bakery every day for fresh bread. Or maybe shorter workweeks and more vacation time allow them more opportunities. Whatever the reason, experts predict they'll match our weight gain as soon as they catch up with the changes modernization brings.

Then they'll learn, as we have, that maintaining a healthy weight is not just about spending more time at the gym; it's about being more active in your daily life. Take a look at your routine. Are you ignoring opportunities to enjoy movement? Have you given up habits that make you use your muscles? If so, take them back. They're the only ways to correct the calorie imbalance that makes you gain weight. --C.R.

Why we overeat

The jumbo-izing of Americans can't be entirely blamed on evil intentions of Dairy Queen franchisers or potato-chip manufacturers. "For many years we've asked the food industry to provide good-tasting, cheap, abundantly available food," says obesity expert James O. Hill. "No one foresaw that the result would promote overeating--nor that as our food supply becomes more 'obesity conducive,' fewer people would be able to choose a healthy diet."

Fair enough. But even when we're ready, willing and able to eat well, it's hard to resist creative food marketing. Some of our nation's most innovative minds are hard at work thinking up ways to sell us food that makes us fat.

Eating out: Life in Whopper world

The more often we patronize restaurants, the more likely we are to pack on pounds, say Tufts University researchers. "A major reason people are getting bigger is that commercial servings have gotten larger," says Melanie Polk, R.D., director of nutrition education at the American Institute for Cancer Research (AICR). The average Reuben sandwich at a midpriced eatery weighs 14 ounces and contains 916 calories, and the "healthier" chef's salad (5 cups with 1/2 cup dressing) contains 930 calories, says the Center for Science in the Public Interest. With half of all adults eating at a restaurant on any given day, it's no wonder we're gaining weight.

Oddly, most Americans haven't noticed that they eat more when they eat out. In an AICR survey, 62 percent of respondents thought restaurant portions were the same size or smaller than they were a decade ago. Worse, few of us know what a normal-size portion is. Even among those who do know, 86 percent seldom or never measure out their food. Then there are the 25 percent of us who admit that the amount we eat depends on how much we're served. To get a handle on your portions, try this:

* Spend some time measuring out standardized servings at home so you're better able to "eyeball" portion sizes.

* Visualize what you want to eat before you order.

* Ask for a doggie bag when you order, then put half your meal in the bag before taking a bite.

Snack foods: We dare you to eat just one

We nibble all day on crackers, energy bars, meat snacks, mini-cookies, bagel chips. That's because the line between meals and snacks has blurred, says Bernard Pacyniak, editor of Snack Food and Wholesale Bakery. "Thirty percent of our calories now come from snacks," he says, "and there are many more to choose from--20-30 percent more salted snacks alone in the last decade."

This means trouble because while variety in fruits and vegetables is our ally, it's our enemy when it comes to snack foods. The American Journal of Clinical Nutrition has reported that people who eat a wide variety of sweets, pizza, pasta and potatoes tend to gain weight, while those who eat a wide array of vegetables are able to lose pounds. This is one case when limiting choices is better. "If you buy three boxes of one kind of cookie, you'll probably eat less of them than if you buy one box each of three kinds of cookies," says Brian Wansink, Ph.D., a professor of marketing and nutritional science at the University of Illinois.

Neither can you depend on your appetite to control how many snack calories you'll consume. Wansink has found that people eat 70 percent more M&M's when they're served in a larger bowl, and that eating from an extra-large tub of popcorn inspires moviegoers to eat 44 percent more than they'd eat from a large size. Some strategies to combat snack traps:

* Limit your choices of snacks and buy the smallest packages. Opt for fresh or dried fruits and vegetables.

* Avoid eating out of a bag or carton; instead, put a measured amount in a bowl or on a plate.

* Order "small" sizes of soft drinks, popcorn and the like; they're not really that small.

Fast food: Penny wise, pound foolish

To keep you coming back, fast-food outlets offer contests, prizes and free merchandise. They also promise you a bargain, with what the trade calls "decoy pricing." By varying the prices of components, such as burgers, fries and drinks, fast-food companies tempt you to buy a larger "supersize" or "value" meal, even when all you wanted was one item. What looks like a bargain can bump up your calorie intake by 40-50 percent.

With fast foods so much a part of daily life, it's hard to resist the come-ons. "To protect yourself from an environment in which food is overabundant, you must make a conscious choice to be different from the culture," says Sonja Connor, M.S., R.D., a research dietitian at Oregon Health Sciences University in Portland. Approach fast food with these self-defense tips in mind:

* Think a la carte: Don't assume that the value meal is a money saver.

* Take along fruit or carrot sticks to replace the fries or the shake you really didn't want.

* Whenever possible, plan a sit-down meal in a restaurant that offers healthy choices rather than getting so hungry and rushed that you opt for fast food.

Taking control of your eating

No matter how cleverly the food industry packages its products, maintaining a healthy weight is up to you. Here are some approaches suggested by experts.

* Know thyself: People with average self-control eat more when they have more food on hand, says food-marketing expert Wansink. People who have high levels of self-control eat less when they've got a large supply of food on hand; "opening the floodgates" doesn't happen with them. Figure out which type you are, then stock your larder accordingly.

* Stay alert: Whenever we "space out" we eat more. "We're also more impressed by peripheral cues then," Wansink says. Some cues are put there by the food industry (the color red stimulates appetite, for example; orange connotes affordability). Others are accidental, such as how much the man sitting next to you at the coffee-shop counter appears to be enjoying his apple pie. Pay attention. Anticipate these external cues to eat, and focus on staying in touch with your internal hunger and satiety signals.

* Get real: Besides marketing food as a good buy, advertisers also sell an idealized image, promising to serve up fun, excitement, a sense of belonging. But no matter how they package it, they're selling calories. And Americans fall for it, buying foods named Whopper and Grand Slam while underestimating the number of calories they consume daily by as much as 25 percent. Don't employ wishful thinking. That hamburger is called a Monster Burger for a reason. --M.E.S.

12 ways to move more every day

1. Walk to at least one errand per week, suggests Barbara Moore, Ph.D., president of ShapeUp America! If you can't walk the entire distance, park a couple of blocks away.

2. Set an alarm and get up once an hour while at work to walk around for five minutes. Stretch or do biceps curls (use water bottles if you don't have anything else). By the end of an eight-hour workday, you'll have gotten 40 extra minutes of activity.

3. Walk to a co-worker's office to talk instead of sending e-mail. Stanford University exercise expert William Haskell, M.D., has calculated that using e-mail for five minutes per workday hour will add a pound a year (or 10 pounds between the ages of 20 and 30).

4. Give up using one automatic gadget, like an electric can opener. Or try "losing" your remote control.

5. Take the stairs at least once a day.

6. Whenever possible, have "walking meetings," taking care of business with co-workers while walking around the block.

7. If you're Velcro-ed to the couch during "Dawson's Creek" or "The West Wing," get up during commercials and do some leg lifts, crunches, stretches - or simply walk around the house.

8. Don't drive-thru. Get out of the car and walk inside to get food.

9. Do the portable-phone workout: Instead of plopping down with the cordless, pace around the room, stretch or do torso twists.

10. Take a pass on delivery of anything.

11. Do three physical chores a day. Sweep, dust, wash windows.

12. Move as you wait. Walk up and down escalators; do calf raises while in elevators, in line or waiting for a light to change. --C.R.