Medifast Diet Overview


Weight Loss Short-term
Weight Loss Long-term
Easy to Follow
For Diabetes
For Heart Health

Scores are based on experts' reviews

Pros & Cons

  • Nutritionally sound
  • No counting carbs, points, or calories
  • Powdered, just-add-water food
  • Might be tough to stick with

Do's & Don'ts

Do: Whip up a “lean-and-green” meal each day See more Do's & Don'ts




Resembles these U.S. News-rated diets:

Slim-Fast, Jenny Craig, Nutrisystem

The aim:

Weight loss; diabetes control.

The claim:

You’ll lose up to 2 to 5 pounds a week without being hungry.

The theory:

By faithfully sticking to Medifast-made products and supplementing them with one meat-and-veggies entrée each day, you stay full and nourished from lots of protein, fiber, and key nutrients while consuming very few calories—typically 800 to 1,000 for adults. That’s just part of the explanation, however.

Some carb-curbing also goes on behind the scenes. Because carbs are your main energy source, restricting them sends the body to the best available alternative fuel: fat. Medifast is said to curb carbs just enough—30 to 50 grams a day below the minimum amount recommended in the government’s 2010 Dietary Guidelines—to start burning fat.

Moreover, the carbs in the Medifast diet are low on the glycemic index, a measure of a carb’s effect on blood sugar. Low-GI carbs are said to keep your blood sugar and metabolism steady and you feeling fuller longer.

How does the Medifast Diet work?

Most Medifast dieters use a “5&1” plan. It provides six meals a day, five of them 100-calorie Medifast products—a shake, bar, oatmeal, soup, or even cheese puffs. The sixth meal, which you can have at any time, is a “lean-and-green” entrée you prepare yourself, built around 5 to 7 ounces of lean protein (check a list) and three servings of non-starchy veggies (ditto). Once you’re at your goal weight, you slowly wean yourself off Medifast food during transition and maintenance phases tailored to your ideal caloric intake, and gradually reacquaint yourself with starchy veggies, whole grains, fruit, and low-fat dairy products.

Medifast also markets specific plans for diabetics, seniors, teens, vegetarians, nursing mothers, those with gout, those who will or have had gastric banding surgery, those who have celiac disease or gluten sensitivity, and those taking anticoagulants. Antioxidant-loaded products and supplements that Medifast says will benefit your heart, sleep, digestion, and metabolism are extra-cost options. There’s also a very-low-calorie plan, conducted under physician supervision.

Will you lose weight?

Medifast has been evaluated more rigorously than many popular diets, but it’s difficult to put a realistic number on the weight you’ll lose.

The studies, as is true for most diets, have been small, with many dropouts. Short-term, it seems impossible not to shed at least some pounds; you’re eating half the calories most adults consume. Research seems to support that. The long-term outlook is less promising. Here’s a closer look at the data:

  • A small study, funded and designed by Medifast and published in 2010 in Nutrition Journal, randomly assigned 90 obese adults either to the 5&1 plan or a calorie-restricted diet based on government guidelines. After 16 weeks, those in the Medifast group had lost an average of 30 pounds compared with 14 pounds for the other group. But 24 weeks later, after dieters gradually upped their calories, the Medifast dieters had regained more than 10 pounds while the others had put back about two pounds. At week 40, the Medifast group had less body fat and more muscle mass than at the start, but didn’t significantly outperform the control group. By the end, almost half of the Medifast group and more than half of the control group had dropped out.
  • A Medifast-funded study of 119 overweight or obese type 2 diabetics, published in the Diabetes Educator in 2008, randomly assigned dieters to a Medifast diabetic plan or to a diet based on recommendations from the American Diabetes Association. The Medifast group had lost an average of 10½ pounds after 34 weeks, but after 86 weeks had regained all but 3 pounds. The diabetics on the ADA-based diet had lost an average of 3 pounds at 34 weeks; at 86 weeks they had gained it all back plus a pound. The dropout rate was nearly 80 percent.
  • In a Medifast-funded analysis published in 2008 in the journal Eating and Weight Disorders, researchers looked at the medical records of 324 overweight or obese Medifast dieters who were also taking a prescribed appetite suppressant. The patients lost an average of 21 pounds at 12 weeks, 26½ pounds at 24 weeks, and 27 pounds at 52 weeks. Additionally, about 80 percent of them had lost at least 5 percent of their initial weight at all three assessments. That’s not bad—if you’re overweight, losing just 5 to 10 percent of your current weight can help stave off some diseases.

    These figures come with a few asterisks, however. First, they’re based on completers, or those who finished the 52-week program and were thus more likely to lose a greater amount of weight. (In an analysis that accounted for dropouts, weight loss was still significant but less dramatic.) Second, a review of patient data carries less weight than a study with a control group. Finally, in an analysis where researchers split dieters into groups of consistent Medifast users (those who reported consuming at least two shakes per day at each check-in) and inconsistent ones (the rest of them), weight loss wasn’t significantly different.

Does it have cardiovascular benefits?

Possibly, but no more than many other diets.

  • In the Nutrition Journal study described in the previous section, researchers reported declines in blood pressure, pulse rate, and blood levels of C-reactive protein, a marker of inflammation that may predict heart disease risk, in the Medifast and control groups at week 40.

    The study also reported on waist size and amount of abdominal fat, which are thought to be indicators of heart disease risk. At week 40, Medifast dieters had lost an average of about 4 inches around the waist, the control group about 1½ inches. The abdominal “fat rating” for both groups had decreased as well, but the Medifast group performed slightly better. At week 40, total cholesterol was not significantly lower for the Medifast group but had dropped appreciably for the control group. Neither group showed improved levels of triglycerides, a fatty substance that in excess has been linked to heart disease, at 40 weeks.
  • In the Diabetes Educator study described above, the Medifast dieters had significantly higher “good” HDL cholesterol and lower systolic blood pressure after 86 weeks, but neither change was significant when compared to the control group.

Can it prevent or control diabetes?

Possibly, but research does not show an advantage over other diets.

Prevention: Being overweight is one of the biggest risk factors for type 2 diabetes. If Medifast helps you lose weight and keep it off, you can help tilt the odds in your favor.

The preliminary findings from the Nutrition Journal study on waist circumference and abdominal fat, cited in the cardiovascular section above, suggest that Medifast dieters may be able to reduce two diabetes-associated risk factors.

Control: Medifast offers specific plans for diabetics; the amount of calories, carbs, and "lean-and-green" meals they provide are similar or vary slightly from the typical adult plan. The Diabetes Educator study described above indicated favorable short-term changes in Medifast dieters to their fasting blood glucose and insulin levels at 34 weeks, but at 86 weeks the changes had all but disappeared.

Are there health risks?

Studies haven’t shown major problems. Side effects might include leg cramps, dizziness or fatigue, headaches, loose skin, hair loss, rashes, gas, diarrhea, bad breath, constipation, and (for women) menstrual changes.

The apparent absence of noteworthy risks does not mean Medifast is safe for everyone. Those who shouldn’t be on the 5&1 program include:

  • Pregnant women
  • Type 1 diabetics
  • Those who have recently suffered a heart attack or stroke
  • Those with severe kidney or liver disease
  • Others—see the full list here

How well does it conform to accepted dietary guidelines?

Fat. In line with the federal government’s 2010 Dietary Guidelines.

Protein. At 40 percent of daily calories, the amount of protein in the 5&1 adult plans is over the government’s 35 percent cap.

Carbohydrates. Typical adult plans fall just below the government’s recommendation.

Salt. The majority of Americans eat too much salt. Most adults should consume no more than 2,300 milligrams of sodium, but if you’re 51 or older, African-American, or have hypertension, diabetes, or chronic kidney disease, the cap is 1,500 mg. A typical day’s worth of Medifast meals totaled about 1,200 mg. of sodium. If you’re diligent about keeping salt to a minimum in your lean-and-green meal, you’ll be fine.

Other key nutrients. The 2010 Dietary Guidelines call these “nutrients of concern” because many Americans get too little of one or more of them:

  • Fiber. Getting the recommended daily amount—22 to 34 g. for adults—helps you feel full and promotes good digestion. Depending on your age, you might fall just short on the 5&1 plan.
  • Potassium. A sufficient amount of this important nutrient, according to the 2010 Dietary Guidelines, counters salt’s ability to raise blood pressure, decreases bone loss, and reduces the risk of developing kidney stones. It’s not that easy to get the recommended daily 4,700 mg. from food. (Bananas are high in potassium, yet you’d still have to eat 11 a day.) Most Americans take in far too little. You likely won’t meet the government recommendation, but a Medifast representative says you should get about 80 percent of the way there, roughly as much as the average American.
  • Calcium. It’s essential not only to build and maintain bones but to make blood vessels and muscles function properly. Many Americans don’t get enough. Women and anyone older than 50 should try especially hard to meet the government’s recommendation of 1,000 mg. to 1,200 mg.; on the 5&1 plan you should get from 1,000 mg. to 2,250 mg. As you move off the program, you can meet the goal with low-fat dairy products and calcium-fortified juices and cereals.
  • Vitamin B-12. Adults should shoot for 2.4 micrograms of this nutrient, which is critical for proper cell metabolism. Medifast provides more than enough—2.9 to 8.3 micrograms on the 5&1 plan, according to company estimates. Fish like salmon and trout, along with yogurt and fortified cereals, are good sources when you’re off on your own.
  • Vitamin D. Adults who don’t get enough sunlight need to meet the government’s 15 microgram recommendation with food or a supplement to lower the risk of bone fractures. The 5&1 plan provides 10 to 34 micrograms. Later, when you wean yourself off Medifast products, low-fat dairy and fortified cereals will help supply the recommended amount. Just 3 ounces of sockeye salmon, which packs about 20 micrograms of vitamin D, will satisfy the requirement.

Supplement recommended? No.

How easy is it to follow?

It’ll likely be difficult not to yearn to stray from the limited menu and small portions. But you get to eat every couple of hours and don’t have to track much of anything—there’s no counting carbs, points, or calories.

In the Nutrition Journal study described in the weight-loss section, about half of both the Medifast and the control dieters had dropped out at 40 weeks. In the Diabetes Educator study, Medifast retention was much better than the other diet—but that still only meant 16 Medifast dieters finished the entire 86 weeks while eight in the other group did.


Recipes are available. Eating out is doable. Alcohol isn’t recommended. Ordering meals and prepping them is quick and easy. Online resources and in-person centers provide support and extra motivation.

Recipes. Medifast gives you some prep tips and limited condiment options for your lean-and-green meal. A recipe box would likely go unopened anyway—you can get by sautéing meat, steaming veggies, and adding a little sauce or seasoning. If you want, you can purchase a Medifast cookbook full of lean-and-green meal recipes or comb discussion boards for dieter-approved suggestions.

Eating out. Challenging but not impossible. Medifast suggests making your meal out the lean-and-green meal for the day. You’d have to go à la carte, requesting only your 5-7 ounces of lean protein and a side of non-starchy veggies. If you have no choice, you could bring your powdered Medifast meal and ask for water to prepare it.

Alcohol. Not recommended. It adds calories and makes you hungry, according to Medifast.

Timesavers. Choosing a plan and ordering is simple, and automatic delivery is available. Food prep is fast—the most difficult instructions for Medifast meals require adding water and nuking in the microwave. Even unskilled cooks should be able to quickly tackle the lean-and-green meal.

Extras. Online and for free, you can forge relationships with other Medifast dieters via discussion boards, blogs, and chat rooms. You can track your meals and exercise or talk with a Medifast employee for an oomph of motivation. And you can access a slew of informational guides and FAQs. You can also choose to do a pricier one-on-one program through one of Medifast’s more than 60 centers, if there’s one in your area.


Nutrition experts emphasize the importance of satiety, the satisfied feeling that you’ve had enough. In the Nutrition Journal study described in the weight-loss section, researchers reported no significant differences in satiety between Medifast and other dieters in either post-meal or general fullness. The Diabetes Educator study also found no significant differences in appetite between diet groups.

Medifast also says its meals have a high “fullness index,” meaning the high protein and fiber content should keep you feeling fuller longer.


Medifast products likely won’t win cuisine competitions. But a Medifast representative says the company puts its products through a taste panel before making them available and constantly monitors customer feedback, developing more favorites and discontinuing the duds.

How much does it cost?

The typical four-week 5&1 adult package runs $315. Two-week packages are available for $162.50. The additional grocery tab won’t break the bank—you’ll be buying very little protein and veggies to supplement.

Does the diet allow for restrictions and preferences?

Most dieters will find a Medifast program that fits their needs—choose your preference for more information.

Vegetarians: Doable, if you’re willing to accept a limited menu of Medifast products. While lacto- and lacto-ovo vegetarians likely won’t feel deprived, ovo-vegetarians have just three category options for Medifast meals—shakes, oatmeal, and scrambled eggs. Medifast has a downloadable PDF with approved products and suggestions for the lean-and-green meal.

Vegans: No plan. Medifast products contain either egg or dairy ingredients.

Possible. Around 30 Medifast products have been certified gluten-free, including select shakes, soups, eggs, and pudding.

With some extra attention paid to preparing the lean-and-green meal, all plans should be low-sodium friendly.

Medifast can tell you which of its foods are kosher.

Dieters can work with Medifast counselors to choose halal options.

What is the role of exercise?

Encouraged, with a few caveats.

If you haven’t been exercising, wait until after you’ve been on the program two to three weeks and have your physician’s OK.

If you have been exercising, dial down your regimen until you’re used to the new calorie level, then you can gradually ratchet up intensity and duration.

Medifast recommends 30 minutes a day of a moderate-intensity exercise you enjoy and can easily incorporate, like walking. You should limit vigorous activity to 45 minutes a day. Medifast offers a crash course in exercise basics in a downloadable PDF.

Last updated by Kurtis Hiatt | December 27, 2012

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