Many people find that when they stick with a diet — any diet — it works. But studies show that most of us can't make ourselves stick to a diet long-term.
Now, there is growing focus on behavioral tricks to help people change the way they think about food and eating.
Lori Maslin, a 45-year-old Maryland lawyer, is passionate about food. She says she likes to cook, loves to eat, and has never been one to say "no" to a rich, chocolaty dessert.
As she prepared for an annual beach weekend with her friends, she faced a dilemma. She wanted to stick to her diet, but she knew there would be a lot of temptation.
"On the way [to the beach], we always stop at this restaurant called Red, Hot and Blue," she says. "It's a Southern barbecue place, and they have the most killer chocolate cake. And I love chocolate cake."
Maslin's approach to dieting these days has a lot to do with planning. Days before her trip, she decided she would hold back on the ribs and coleslaw and leave room for the cake.
"[The cake] was just as good as I knew it would be," Maslin says, "and I shared it with some of the girls, and I didn't feel guilty about it!"
Maslin has taken off 35 pounds over the past year and a half. Weight Watchers taught her what sorts of foods she should be eating, and in what quantities. But to keep it off, she works with a diet coach, psychologist Judith Beck.
"What's important to realize," Beck says, "is that behind every behavior change, there's a lot of thinking changes."
Beck's father, Dr. Aaron Beck, pioneered a treatment called cognitive therapy back in the 1960s. Rather than asking people to reach back to childhood for the source of emotional problems, the Beck approach is to change the way people think about their problems.
For dieters, this means catching themselves whenever they have a sabotaging thought, such as, "Oh, I'll never be thin, so why not just tear into this bag of chips?"
When these sorts of thoughts take hold, dieters cave, and then convince themselves they have no willpower at all — which, Beck says, usually isn't true.
"Dieters do have willpower," she says. "Most dieters have lost weight before. They've just gained it all back, so their willpower is a little inconsistent."
Beck has a lot of tricks to keep willpower strong.
Maslin has adopted one of them as almost a mantra. Every day, she repeats to herself, "No choice," which means she has no choice about sticking with just the foods she has planned out for the day — even when she's ordering off a three-page menu. Maslin just ignores the unhealthy options.
Maslin says that in all her years of dieting, choosing a skimpy wrap over a meaty hoagie used to make her feel deprived. But now she distracts herself, by focusing on what she is gaining. Beck suggested that Maslin create a list of eight things that are great about losing weight. Maslin now carries this list in her wallet.
At the top of the list is a better self-image. Next, a better clothing selection. The list goes on, Maslin says, with entries like, "No more feeling the need to stand behind somebody in a photo."
Carrying a list like this may sound funny, but Maslin says it helps her stay in control.
Martin Binks oversees Duke University's Diet and Fitness program. He says these tricks borrowed from cognitive therapy can be the missing piece for dieters who are trying to make a lasting change. Binks says effective dieting takes time and a personalized approach.
"What seems like the best tool to one person might seem kind of silly to another," he says.
Carrying around a food journal or a list of benefits may work for some dieters, while group support or scheduling weigh-ins with a doctor will work for others.
At the end of the day, Binks says it is important for diet gurus to be honest.
He says they should "admit to people that weight control is difficult. It takes sustained effort on making a lot of small changes that can last."
Not everyone will be successful, and no one can stick to their plan 100 percent of the time.
Maslin says that every once in a while, she reverts to eating big handfuls of popcorn drenched in butter while watching late-night TV.
"I'll catch myself, and I'll have to slow down," she says.
When the going gets tough, Maslin thinks ahead to Sunday mornings when she meets her friends for breakfast.
"To have them say, 'You look so good, You don't need to lose anymore!'" says Maslin, that will keep her going — for at least another week.