Meal Replacements Don't Help Obese Teens

Dietetic shakes and prepackaged entrees help obese teenagers lose weight loss at first. But "meal replacements" were no better than a standard low-calorie diet for helping young people continue losing weight over the course of a year....

Dr. Robert L. Berkowitz, Children's Hospital of Philadelphia, and his team note in their report that swapping regular meals for shakes, bars or prepackaged entrees can be a useful weight loss strategy for adults.

One reason that these meal replacements may work is that they take the guesswork out of dieting; people often sharply underestimate their calorie intake when they eat regular foods. Given that adolescents also underestimate how many calories they consume, the researchers sought to investigate whether meal replacements might be helpful for them, too.

The researchers randomly assigned 113 obese teens and their families to one of three regimens for a year: (1) a standard 1,300- to 1,500-calorie-a-day diet; (2) four months of meal replacements (three SlimFast shakes, one prepackaged entrée, and five servings of fruits and vegetables per day) followed by eight months on the conventional diet; or (3) an entire year of meal replacements.

At four months, patients in the meal replacement groups had reduced their body mass index (BMI) by a mean of 6.3%, compared to 3.8% for teens in the low-calorie diet group.

But by the end of the year, there was no significant difference in mean BMI reduction between the three groups: 2.8% for the low-calorie diet group, 3.9% with four months of meal replacements, and 3.4% with a year of meal replacements.

One-third of the patients dropped out of the study. Among those who stuck with it, adherence waned as time wore on. By the end of 12 months, the researchers note, the meal-replacement group reported using SlimFast only 1.6 days a week, compared with 5.6 days a week in month two.

"The potential benefit of (meal replacement) in maintaining weight loss was not supported," the researchers conclude, and further study is needed to find ways of getting obese teens to start diets and stay on them.