Meal Replacement Diet May Improve Initial Weight Loss Amounts Compared to Patient Controlled Plan

Weight loss is of major interest for both medical and marketing reasons. Medically speaking, being overweight or obese can increase risk of heart disease, diabetes, cancer, and others illnesses. Medical concerns and increasing rates of obesity in the general population have driven the market to create many diet options. One popular type of diet method is the meal replacement plan. With meal replacement plans, you replace the food you would normally eat with prepackaged meals, shakes, and/or bars. By using these replacements, these plans help you control your caloric intake and consume adequate levels of important nutrients. The Medifast meal replacement program is one such plan.

Researchers from Medifast research and development in Maryland examined the benefit of a meal replacement diet plan compared to a low-calorie diet with meals chosen and provided by the dieter. The research found that the meal replacement plan may increase weight loss in patients that continued with the diet.

About the Study

The randomized trial included 90 obese adults. The participants were assigned to either portion-controlled meal replacements or a diet guided by the USDA food guide pyramid (exact meals were made and determined by individuals). The meal replacement plan provided five meal replacements and recommended a total of 800-1,000 calories per day. Participants in the participant-controlled plan created their own meals aiming for a total of 1,000 calories per day. These plans were followed for 16 weeks and then the patients entered a 24 week maintenance phase. In the maintenance phase, both groups continued to either eat the meal replacement options or participant-controlled foods, but they were allowed to increase the amount of calories.

After the initial 16 weeks:

  • The meal replacement group had greater weight loss—29.7 lbs (13.5 kg) compared to 14.3 lbs (6.5 kg) in the participant-controlled program.
  • More participants in the meal replacement group lost 5% or more of their weight than the food-based program.

After 24 weeks of maintenance (40 weeks total):

  • The meal replacement group regained an average of 10.5 lbs (4.8 kg).
  • Those on the food-based plan regained an average of 1.7 lbs (0.8 kg).
  • More participants in the meal replacement group maintained at least 5% weight loss from their starting weight.

Of the total participants who entered the trial, 53% completed 16 weeks of the trial and 51% completed 40 weeks. The results listed above only included the participants who remained in the study.

How Does This Affect You?

The study was a randomized trial, which is considered a very reliable study method. However, there were some problems in this study. First, there was a high number of people who did not complete the study. When a lot of people do not finish a study, it decreases the reliability of the results. Also, the weight loss seen in the above numbers were only seen in patients who continued the diet to the end. The weight loss numbers do not include what happened to the almost 50% of patients who did not complete the study. Both of the diets being compared were very low calorie, and it appears that they were hard to continue for the study period. Also, the counselors working with the participants knew which diet the participants were on. Since the counselors were aware of which participant had which diet, they may have influenced the outcomes for either group. This study was conducted by Medifast, the company that makes the meal replacement product used, which can also add some suspicion to the results.

Your individual goals, preferences, and health should all be taken into consideration when choosing a diet plan. A diet plan that provides pre-made meals can be a convenient way to help you get your nutrition and stay on your diet, but becoming too dependent on pre-made meals may lead to problems when you move back to your "normal" diet. You are also more likely to succeed if the diet is not based on extremes. For example, the diets here had very low calorie levels for the first 16 weeks. The high dropout rates from both diet groups were likely due to the severe calorie limititations. Avoiding diets with any extremes may make it easier for you to stay on the diet and maintain your weight loss. Talk to a dietitian or your doctor to help you sort through different diet options and create a plan that can help you lose weight and get the proper nutrients.


American Dietetic Association
United States Department of Agriculture


Davis LM, Coleman C, Kiel J, et al. Efficacy of a meal replacement diet plan compared to a food-based diet plan after a period of weight loss and weight maintenance: a randomized controlled trial. Nutr J. 2010 Mar 11;9:11.
Last reviewed June 2010 by Brian P. Randall, MD
Last updated 6/8/2010

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