Traditional strategies for encouraging young people to eat healthily have come under fire in the findings of four US-based research teams.

Advertisements for weight loss programs that portray overweight and obese individuals in a negative manner could actually lead to weight gain, according to a study at the University of California at Santa Barbara.

In their study, they observed women who perceived themselves as being overweight reach for more calorie-laden snacks after reading a news article that portrayed extra pounds in a negative light.

On the flip side, a control group consumed less fattening snacks after reading a neutral article.

"Simply reading about the potential for weight stigma was enough to impair self-regulation among overweight women," says co-author Jeffrey Hunger.

Another practice to zap, according to researchers at Harvard University, is calorie counting.

"If you're counting calories, seemingly innocuous reminders of tempting, high-calorie food -- such as an empty donut box in the middle of a conference table -- can lead to worse performance on difficult tests of attention and reasoning ability," says lead researcher Aimee Chabot.

Chabot and her team recommend simple strategies such as steering clear of added sugars or eating only at predetermined times.

Young people are confronted day-in and day-out by images of tempting snacks in advertisements, which are well known to lead to poor food choices.

In response, a research team at the University of Minnesota was pleasantly surprised to find that photographs of carrots and green beans on school lunch trays increased students' appetite for veggies.

Getting teens involved incurrent controversiesover Big Food could be another important strategy, according to researchers at the University of California at San Diego and the University of Texas at Austin.

Educating teens about deceptive marketing practices that lead shoppers to believe foods are healthier than they are and the extraordinary lengths companies go to in making their products as addictive as possible could increase interest in healthy eating, they say.

The four teams presented their work in a symposium called "Challenging Misconceptions About the Psychology of Food Choice," at the Society for Personality and Social Psychology's 16th Annual Convention in Long Beach, California, which ended Saturday.