Meal replacements like shakes, bars and prepackaged entrees can often be a boon for people who are trying to lose weight, but a new study at the Children’s Hospital of Philadelphia found that they weren’t a good long-term solution for obese teens.
For the new study, researchers randomly assigned 113 obese teens and their families to different diets for a year. One group of teens ate self-selected low-calorie meals not exceeding 1,300 to 1,500 total calories per day. The other group ate meal replacements (three SlimFast shakes and one prepackaged entree), along with five servings of fruits and vegetables. Four months into the study, participants in second group were randomized to a second-phase diet: some were put on the low-calorie self-selected diet, while the rest stayed on meal replacements. (More on Time.com: Do Parents Discriminate Against Their Own Chubby Children?)
At the four-month mark, all participants had lost weight, but the teens on meal replacements lost more — a 6.3% reduction in body mass index (BMI) versus 3.8% for the low-calorie group.
But by the end of the one-year study, many participants had regained much of the weight they had lost, resulting in no significant differences in weight loss between the groups: on average, the teens had reduced their BMI 3.4% since the beginning of the study.
The results underscore one of the many difficulties of dieting: keeping the weight off long term. Many dieters regain weight because they can’t stick to rigid eating programs for long: one-third of the participants in the current study dropped out before its conclusion. The monotony of the meal-replacement diet couldn’t have helped either: teens in the meal-replacement group started out drinking SlimFasts 5.6 days a week (in Month 2); by the end of the study, they were only able to tolerate the shakes 1.6 days each week. (More on Time.com: Special Report: Overcoming Obesity)
“The potential benefit of (meal replacement) in maintaining weight loss was not supported,” the researchers concluded.
So for those of you who are gearing up to begin a weight-loss program in the New Year, it helps to remember that austerity isn’t the best strategy long-term. Focus on variety — both with your diet and your exercise regimen — and manageability instead.