Obese teenagers opting for replacement diet as a quick-fix solution in their battle of the bulge may shed weight quickly in the initial stages of dieting. Unfortunately in the long run these replacement meals are no better than regular standard low calorie diets.

Meal replacement products comprising bars, shakes and other types of pre-prepared food rations offer a way to help control calorie intake without people having to worry about counting them because they contain determined amounts of calories and nutrition. However, unlike adults, teenagers may have trouble estimating portion sizes or adhering to the regimen and find themselves eating too often or choosing foods high in fat and calories. In such a scenario, meal replacements may not work for them.

In order to determine whether meal replacements help teenager shift weight, the researchers recruited a group of 113 obese teenagers of America and split them into three groups. The participants of each group were assigned to a different diet regime. One group was asked to follow a standard 1,300 to 1,500 calorie diet daily for a period of a year. The second group was put on a meal replacement diet for four months, which was later swapped with a low-calorie diet for eight months. The third group was assigned to meal replacements (three SlimFast shakes, one prepackaged entree, and five servings of fruits and vegetables) for an entire year.

It was noted that one-third of the participants dropped out of the study. Among those who continued, strict adherence to the allotted regimens declined. At the close of the study, teenagers on the meal-replacement diet were using SlimFast for only 1.6 days in a week compared with 5.6 days in the second month.

During the first phase of the study at four months, teenagers on the meal replacement diet exhibited 6.3 percent loss in their body mass index - a number, derived by using height and weight measurements, that gives a general indication of whether or not weight falls within a healthy range - (BMI) as opposed to 3.8 percent for those assigned to a low-calorie diet. In the second phase, the participants in all the three groups gained weight. In the last phase at one year, the study subjects assigned to low-calorie diet group lost 2.8 percent of their BMI.

Those put on meal replacement plus low-calorie diet group lost 3.9 percent while teenagers in the straight meal replacement group lost 3.4 percent of their BMI. In statistical terms there was not much variation in weight loss among the three groups.

The researchers concluded that the potential benefit of meal replacement in maintaining weight loss was not supported and suggested further study to find ways of getting obese teens to start diets and stay on them.