Losing weight is simple: Eat less and exercise more. Why that's so difficult for so many people is embedded deep in the human psyche.



"If we can understand how personality is contributing to weight gain, we can develop interventions to help people deal with it," says Angelina R. Sutin, a researcher at the National Institute on Aging who led a study published last year comparing the body mass index, or BMI, and personality traits of nearly 2,000 Baltimore residents over 50 years.

In the study, those who scored high on neuroticism—the tendency to easily experience negative emotions—and low on conscientiousness, or being organized and disciplined, were the most likely to be overweight and obese. Impulsivity was strongly linked to BMI, too: The subjects in the top 10% of impulsivity weighed, on average, 24 pounds more than those in the lowest 10%. People who rated themselves low on "agreeableness" were the most likely to gain weight over the years. The study was published in July in the Journal of Personality and Social Psychology.

The link between emotions, food and weight control starts at a very early age. Toddlers who had low-quality emotional relationships with their mothers are more than twice as likely to be obese at age 15 as those who have closer bonds, according to a study of 977 children funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and published in the journal Pediatrics this month.

Mike Sudal/The Wall Street Journal

Diet coaches, nutritionists and cognitive-behavioral therapists have long warned against eating for emotional reasons and urged people who overeat to identify eating triggers.

"Is there anybody who doesn't know that broccoli is better for you than a Big Mac?" asks Renée Stephens, a San Francisco weight-loss coach and author of a new book, "Full-Filled." "What's important is identifying what's going on in our heads and what we're using the food for." Otherwise, any diet is bound to fail, she says.


"You don't have to change your whole personality. You just need to change your thinking, which allows you to change your behavior," says Judith S. Beck, president of the Beck Institute for Cognitive Behavior Therapy in Bala Cynwyd, Pa.


The Night Owl

Sleep-deprived people are not only more likely to gain weight, but they also have a tougher time losing it, one sleep expert says. WSJ's Christina Tsuei answers your everyday health questions in the latest installment of "Is It True?"


Night owls also tend to skip, or sleep through, breakfast, missing an important chance to get their metabolism going early, and they often snack far into the night. That sets the stage for "night-eating syndrome," when people consume a significant portion of their daily intake after dinner, which is associated with obesity and diabetes.

The Fix: Shifting one's biological clock is tricky. Start by forgoing caffeine after noon, keeping lights, TV and other electronics low in the evening and scheduling can't-miss appointments very early. Or simply declare the kitchen off limits after 9 p.m. Staying up late may lose some of its appeal.

The Stress Junkie

People who thrive on competition and deadline pressure may seem high-powered, but what powers them internally are adrenaline and cortisol. Those stress hormones supply quick bursts of energy in fight-or-flight situations, but when the alarm is unrelenting, they can cause health problems, including obesity.

Cortisol stimulates a brain chemical called neuropeptide Y, which boosts carbohydrate cravings. It also makes the body churn out excess insulin and accumulate fat, particularly in the belly where it raises the risk of diabetes, heart disease, stroke and other diseases. People who feel chronically stressed often use food for energy and comfort and rationalize that they've earned it.

The Fix: One of the best ways to burn off excess cortisol is exercise, doctors say. And almost anything that pampers, distracts or relaxes you can serve as a reward, says Cleveland Clinic psychologist Susan Albers, author of "But I Deserve This Chocolate!" and "50 Ways to Soothe Yourself Without Food." (No. 26: a hot bath; No. 34: knitting.)

"Really, what you deserve is to feel good in your clothes," she says.

The Mindless Multitasker

People who habitually work, read, drive, watch TV or do anything while dining often eat more than they realize. "Anything that takes our focus off the food makes us more likely to overeat without knowing it," Brian Wansink, an expert on food, marketing and consumer behavior, wrote in his 2006 book, "Mindless Eating: Why We Eat More Than We Think."

He now directs the Food and Brand Lab at Cornell University. His research shows that few people overeat because they're hungry, but because of myriad other subconscious cues, from family and friends to plates and packages.


The Giver

People who constantly put other people's needs ahead of their own often become emotionally depleted and seek solace in eating. Eating coach Karen Koenig, author of "Nice Girls Finish Fat," writes that many of the clients in her Sarasota, Fla., practice are "ultranurturing, self-effacing, unselfish, generous and caring to a fault." Food works because it's close, it doesn't require burdening others, and it signals comfort and love. But because it doesn't really fill the emotional void that givers have, they keep eating more and more.

Some "givers" also live in fear of disappointing other people or engaging in conflict, so they try to stifle their own feelings with food.

The Fix: Among Ms. Koenig's "de-nicing" techniques are to set reasonable limits on your time and energy; identify your frustrated yearnings and find new ways to take care of yourself. Venting unpleasant emotions—in a journal or in the mirror—will diffuse them faster than food.

The Perfectionist

Like givers, people who drive themselves to be perfect often use food to relieve the pressure. And many set themselves up for failure with impossible weight and fitness goals. Bariatric surgeons say they see a high correlation between perfectionism and obesity; experts in eating disorders say perfectionism is often at the root of anorexia, bulimia and binge eating. Many perfectionists also engage in all-or-nothing thinking that leads them to get discouraged easily with dieting and seek solace again in food.


Write to Melinda Beck at HealthJournal@wsj.com