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The Medifast diet consists of eating mainly prepackaged Medifast meal replacements to reach your desired weight loss. For around $300, you get a month’s worth of meal replacements to be consumed 5 times per day. Medifast states that, on average, dieters lose about 2-5 pounds per week.
How Is This Diet Supposed to Work?
The premise is that by following a low-calorie, low-fat, and low-glycemic index diet the body will use its fat storage for energy. Medifast claims that the protein and carbohydrates in their food will preserve muscle mass while allowing fat loss. With carefully planned meals and support from the Medifast staff, the program is designed to eliminate a lot of the guesswork and calorie counting. Medifast also has a transition and maintenance plan.
The Medifast diet is divided into 3 phases: 5 & 1 plan, transition, and maintenance.
The core part of the diet is the 5 & 1 plan, which you follow until you reach your desired weight loss. During this time you get to eat 6 times per day: 5 Medifast prepackaged meal replacements and one “lean and green” meal, which consists of lean meat and nonstarchy vegetables. Medifast provides over 70 meal replacements to choose from, such as soups, shakes, and bars. Medifast claims that the 5 meals a day cost about $11.
All of these products are fortified with vitamins and minerals to help you meet your nutrient needs, which would otherwise be difficult to do since this diet only provides around 800-1,000 calories per day. All meals are low-fat, low-glycemic, and many are gluten-free. During the weight-loss phase, there are no starches, fruit, or dairy products. And never, in any phase, including maintenance, are there greasy, fried, or sugary foods. You provide the daily “lean and green” meal, which consists of 5-7 ounces of lean meat, fish, or poultry, plus 1-2 cups of vegetables or salad. Meat-free recommendations are also made for vegetarians. Meals with high protein are supposed to be consumed every 2-3 hours, so you will not feel too hungry while on this strict calorie reduction.
The first step is to pick your specific plan, such as:
- Women who are nursing
- People with gout
- People with diabetes
- People who had bariatric surgery
- People taking anticoagulants
- People avoiding soy
Then you pick a support system:
- Online through a community support group
- Online health coach
- In the Medifast center with a personalized coach
- Your doctor
The next step is to order meals. Then, you eat 6 times a day (5 of the Medifast meals) until you reach desired weight loss.
After you reach your desired weight loss, you begin thetransition phase, which gradually reintroduces you to foods that were missing from the weight-loss phase (fruit, starches, dairy) and increases your calorie intake. Over several weeks, there is a transition from the packaged meals. The length of the transition phase is directly related to how much weight was lost. For example, if you lost less than 50 pounds, the transition is 8 weeks. If you lost 50-100 pounds, the transition is 12 weeks. This allows the body to slowly get reintroduced to these foods (fruits, starchy vegetables, whole grains, and dairy).
The final phase of this diet ismaintenance, during which you are encouraged to eat a healthy, balanced diet with all varieties of healthy foods with some Medifast meals. A plan for how many calories you need for weight maintenance is created for you, as well.
The Medifast plan recommends that its subscribers also engage in regular exercise, especially during the transition and maintenance phases.
Additional Features of This Diet
- Free online meal planner, weight-loss tracker, and support
- Access to registered dietitians via phone or online
- One-on-one counseling sessions with health coaches trained in the Medifast diet plan
- Some states have weight-loss centers for in-person support
What Does the Research Say?
Research suggests that going on a meal replacement diet can be a safe and effective way to lose weight for people if they can stick with the diet. Moreover, studies have found that these types of diets can help people keep the weight off and thereby lower their risk of weight-related conditions. Also, one study found that women on a meal replacement diet were more likely to meet their vitamin and mineral requirements than those on a food-based, calorie-restricted diet. A study sponsored by Medifast also found that the diet may promote fat loss, not muscle loss.
There is also some research suggesting that meal replacement diets, such as Medifast, may be helpful for people with diabetes who need to lose weight. A study conducted at John Hopkins University found that a diet consisting of portion-controlled meal replacements helped obese people with diabetes lose weight and maintain that loss for 1 year. It can also help people with diabetes control their blood sugar.
However, there is no research to support the idea that you should avoid certain healthy foods, such as whole grains, low-fat dairy products, and fresh fruit to help promote weight loss. These foods are still an important source of nutrients, and fruits and whole grains are naturally high in fiber. The diet does include these foods in the transition and maintenance phases of the program, but not in the 5 & 1 plan. Also the plan's meals are nutrient-fortified, so you are still getting some essential vitamins from the meals.
Are There Any Concerns With This Diet?
Since this is a low-calorie diet, it should not be attempted without a doctor’s consent. Therefore, talk to your doctor before starting this diet. Because it is so low in calories, it should not be followed by certain groups of people, including women who are pregnant or nursing and very active individuals. Medifast warns of potential side effects, such as constipation, lightheadedness, fatigue, feeling cold, and dry skin or hair.
Also, while the diet seems to have research behind it and valid medical professionals on the Medifast team, any diet that cuts out major healthy food groups (such as fruit or dairy) should be considered only if there are no other alternatives. This diet may be a good idea for people who have failed on a regular healthy meal plan and are going to consider surgery.
While the Medifast diet is not recommended for everyone because it is so low in calories, it may help some individuals with their desired weight loss. Before investing in this diet, consider meeting with a registered dietitian to help you determine what type of diet is best for you. Also, know that as part of the maintenance plan, Medifast recommends continuing to eat several of their meal replacement products every day.
Eat Right—Academy of Nutrition and Dietetics
National Institute of Diabetes and Digestive and Kidney Diseases
Dietitians of Canada
Ashley JM, Herzog H, et al. Nutrient adequacy during weight-loss interventions: a randomized study in women comparing the dietary intake in a meal replacement group with a traditional food group. Nutr J. 2007;6:12.
Cheskin LJ, Mitchell AM, et al. Efficacy of meal replacements versus a standard food-based diet for weight loss in type 2 diabetes: a controlled clinical trial. Diabetes Educ. 2008;34(1):118-127.
Davis LM, Coleman C, 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; 9:11.
Heymsfield SB, van Mierlo CA, et al. Weight management using a meal replacement strategy: meta and pooling analysis from six studies. Int J Obes Relat Metab Disord. 2003;27(5):537-549.
- Reviewer: Dianne Scheinberg Rishikof MS, RD, LDN
- Review Date: 01/2016
- Update Date: 05/08/2014