In another study, students were also exposed to the “survival” words but some werepaid $1 for their participation. They could choose either a salad or a cupcake.

“It was just a dollar,” Salerno said, but it changed the feeling of scarcity. Those who received the dollar were more likely to choose the salad, while those who did not chose the cupcakes, proving their theory that “selecting high-calorie foods was not predicated on taste, but on compensating for perceptions of resource scarcity.”

However, despite underlying anxiety, Duhigg said, habit trumps everything. Pinpoint cues and rewards, then change the routine. The underlying habits will change.

“Willpower is like a muscle. You can teach people habits to make willpower stronger,” he said.

He cites a woman named Lisa who was in total despair, in a rage over her husband leaving her for another woman. She was heavily overweight, drinking and smoking. She flew to Cairo on a whim, as she always wanted to see the pyramids. On her first morning there, she was lying in bed in a blackened hotel room, awakened by the call of prayer from a nearby mosque. In the dark, she reached for a cigarette, only to realize that she had lit up a plastic pen.

She broke down. Completely. Later that day, while traveling through the city in a taxi, she vowed to return in a year to trek across the Egyptian desert that surrounded the pyramids. She knew she had to change one thing: Stop smoking.

She knew she had to replace her smoking habit with another habit. She started jogging regularly.

She started losing weight. She started training for a half marathon. She kept a job after years of job-hopping. She paid off debts. Four years later, she had lost 60 pounds, run her first full marathon, was promoted at work, enrolled in a master’s degree program, bought a house and got engaged.

It was that one decision — she had to stop smoking and had to replace that habit — that led to her new life.

Scientists studying her brain also were astounded: The neurological patterns surrounding her old habits had been overridden by new patterns established in her brain.

“By focusing on one pattern — what is known as a ‘keystone habit’ — Lisa had taught herself how to reprogram the other routines in her life, as well,’’ Duhigg writes in the book.

Ok, back to those pastelitos.

Sheah Rarback, director of nutrition for the Mailman Center for Child Development at the University of Miami, notes that habits affect our food choices. She suggests a common sense approach to eating all year long.

Her tips:

• Eat breakfast (low-calorie, protein-rich foods)

• Drink water before meals.

• Get enough sleep.

• Make vegetables the largest serving on your plate.

• Don’t skip meals.

• To relieve stress, replace eating with physical activity.

Make it easy to make good choices, she adds. Prepare foods ahead to avoid stops for fast food and bring healthy snacks to work or when traveling.

Finally, she said, overeating on Thanksgiving is not going to make a lot of difference. Everyday behavior is what counts. As for the many holiday parties to come, her advice is, don’t fool yourself. Eat small portions of everything, and don’t hold court in front of the food table.

“Don’t say you’re saving up all your calories for the party,” Rarback said, “because you’re going to overeat. Take control of your plate.”