Losing weight is easy.

Keeping it off is not.

Why else would people be searching, time and time again, for that “perfect” diet?

The bad news: One-third to two-thirds of dieters end up gaining more weightthan they lost on their diets, says an article published in an issue of the American Psychologist.

But don’t lose heart. Here’s the flip side of that pancake, er, coin: Long-term weight maintenance is possible, says an article in The American Journal of Clinical Nutrition.

Accordingto research, about 20 percent succeeded at long-term weight loss. But it doesn’t just happen automatically. You need to look past the initial dieting phase and incorporate some strategies, after the weight comes off, to increase the odds that it will STAY off.

And it’s possible.

In writing other articles about weight loss, I’ve come across a lot of research and  interviewed a lot of experts. It’s clear that there are successful losers.

Losing weight is so much more than just the food you eat (or don’t eat). In a very comprehensive article appearing in The Lancet, the authors detail three important things to be aware of in your effort to lose weight:

1. Make small lifestyle changes. There are so many—here are just a few.

• Don’t underestimate the influence of friends. Research shows that your chance of becoming obese increases by 57 percent if a close friend is obese. (Yes, obesity is somewhat contagious.) But the opposite holds true, too: hang out with healthy friends and their habits can rub off on you.

• Consider a food journal. It can help monitor what you eat, reduce mindless eating and consume fewer calories. A large weight-loss maintenance trial found that dieters who kept a record of their food intake lost an average of 18 pounds over six months—as opposed to dieters who didn’t keep a journal (they lost only nine pounds).

• Use smaller plates. Bigger isn’t always better, and can lead to overeating. Use a 9- or 10-inch salad plate for your meal, rather than a standard size, larger dinner plate. You not only consume fewer calories, but you’ll feel just as full. Research proves it!

• Get enough sleep. When you are sleep deprived, your hormones become imbalanced, your hunger cues get mixed up, and your body’s glucose metabolism can change and cause you to hoard calories and store them as fat.

• Drink water. It can help fill you up before and in-between meals. And many people, research suggests, may confuse hunger with thirst. Try drinking a glass of water if you still feel hungry after you’re finished eating. You may find that you’re not really hungry at all.

2. Sustainable diet. What you’re eating in an effort to lose weight has to be sustainable. Take for example, a fad diet like the cabbage soup diet. Sure, you’ll lose weight, because you’re restricting your calories by eliminating choices. Cabbage soup for breakfast, lunch and dinner. Easy—until you re-enter “real” eating, and you’re grabbing everything in sight, because (1) You miss real food like crazy and have all sorts of cravings; (2) You haven’t really taught yourself how to eat to keep the weight off (you’ve only learned how to lose it in the short-term); and (3) You go out to a restaurant, go to someone’s house for dinner, go on vacation, and—surprise!—there’s no cabbage soup.  Extreme diets ultimately fail. (Think: The Biggest Loser. So many gained the weight back because the diets were too extreme, and the weight was lost too fast, say experts. And who can truly exercise seven hours a day—really?)

Your best choice? A high-quality diet that you will stick to. “What we eat is as important as how much we eat,” notes obesity expert Scott Kahan, MD, director of the National Center for Weight and Wellness in Washington, D.C. “There’s no scientific evidence to support the belief that one diet is any better than any other,” he adds.

3. Exercise. Yes, it helps keep you healthy and strong, and lowers your risk of many chronic diseases. But it’s also associated with long-term success in the weight-loss department.

What’s your average day like? Do you sit a lot? Yeah, thought so. Many of us do—unless we have jobs that require us to be on our feet a lot. Face it, we live in a highly sedentary culture. Some estimates say that Americans sit for an average of 13 hours a day (and that doesn’t include sleeping for an average of eight hours a night!)

Another tidbit I came across in my research: Most Americans have to sit all day at work—and they are not happy about it. But, that same survey also found that when people do get up from their desks, more than half “use food as an excuse.”

Doesn’t bode well for weight loss, does it?

One rather obvious lifestyle change: Stand more! Besides its advantages in helping with your posture and increasing your blood flow, standing helps burn extra calories.

I know—sometimes it’s not possible. So, besides standing, be aware of some other easy-to-incorporate lifestyle changes, like:

• Taking the stairs instead of the elevator
• Getting off the bus or subway a few stops ahead of your destination
• Placing your printer away from your desk
• Turning your TV watching time into a workout
• Choosing the farthest spot in the parking lot

If you already exercise, you’re definitely on the right track. It’s a very valid strategy, for sure. When polling its members, the National Weight Loss Registry found that 90 percent of successful losers exercised on average about one hour each day.

Unlike with food and portions, when it comes to exercise, more might be better.