Mayo Clinic Diet (Fad Diet)


The Mayo Clinic diet (fad diet) is a popular diet that was neither created by nor endorsed by the Mayo Clinic, an internationally respected medical research facility headquartered in Rochester, Minnesota. The fad diet promises a weight loss of 10 pounds (4.5 kg) for the person who follows the plan for 12 days. The dieter wanting to lose more weight takes two days off from the regimen and then starts the diet again. A person supposedly could lose more than 50 pounds (22.7 kg) within several months, according to the diet plan. The diet is low in carbohydrates, high in fat, and restricts the consumption of fruits, breads, and dairy products.


Details are vague about how a grapefruit-based diet became known as the Mayo Clinic fad diet. Not even the Mayo Clinic knows how its name became associated with the popular diet, according to the medical facility's website. The Mayo Clinic fad diet is believed to date back to the 1930s, when it was known as the Hollywood diet. It may be that the public thought that following the diet would quickly lead a dieter to have a slender figure like those of the movie stars. The Hollywood diet was a three-week plan that called for the dieter to eat grapefruit with every meal. Small amounts of other foods were allowed, with the calories consumed each day totaling less than 800.

Grapefruit was eaten three times daily because the citrus fruit was said to contain enzymes that burned fat. Because of this special property, the weight-loss plan was also known as the “Grapefruit Diet” or the “Grapefruit and Egg Diet.” The grapefruit diet was spoofed in the 1933 movie “Hard to Handle,” a comedy starring actor James Cagney. He played a con man who promoted various money-making schemes during the Great Depression. While in prison, Cagney's character came up with a grapefruit diet that lasted 18 days.

Some Cagney fans said that the choice of fruit was a reference to “The Public Enemy,” a 1931 movie where the actor smashed a grapefruit into actress Mae Clarke's face. However, grapefruit was a key element in various diets at the time. By the 1940s, one version of the fad diet was known as the Mayo Clinic Diet, according to dietitians at the Mayo Clinic.

It may be that promoters of the high-fat, lowcarbohydrate diet thought that using the Mayo Clinic's name would lead dieters to believe that the food plan was medically sound. The Mayo Clinic disputes this label and refers to the fad weight-loss plan as a “diet myth.”

Although the creator of the Mayo clinic fad diet is not known, the weight loss plan is known internationally. The bogus Mayo Clinic diet has been circulated by various methods over the decades. People typed copies of it for their friends during the 1950s. They duplicated it on office copiers during the 1970s, sent it by fax during the 1980s, and posted online versions of it that could be found on the Internet in 2007.

Over the years, variations of the fad diet have focused on grapefruit, meat, or eggs, according to the Mayo Clinic. Furthermore, the Mayo Clinic fad diet could be the inspiration for the Atkins diet. That plan named for cardiologist Robert Atkins was first described in his 1972 book, Dr. Atkins' Diet Revolution. Twenty years later, he updated the plan in his book, Dr. Atkins' New Diet Revolution. Atkins maintained that people could lose weight by eating meat and cheese, foods that are high in fat. The diet starts with a two-week ban on starchy items like potatoes, food made from white flour like pasta, fruit, and most vegetables.

Published in 2005 and revised and updated in 2017, the book provided information on developing a personalized weight-loss plan. The Mayo Clinic program called for a combination of nutritional eating and exercise. This regimen generally resulted in a weight loss of 1 to 2 pounds (0.45 to 0.90 kg) per week. The book also advised readers that maintaining a healthy weight was a lifelong process involving a nutritious diet and physical activity.


The fad Mayo Clinic diet is also referred to as the grapefruit diet because grapefruit or unsweetened grapefruit juice is consumed at every meal. Diet promoters claimed that grapefruit burned fat, resulting in weight loss. Some diets also called for the consumption of eggs, so the diet was referred to as the grapefruit and egg diet. Other elements of the diet included proteins like meat. The diet specified portion sizes for some foods. For other foods, dieters could eat as much as they wanted. Fried food was allowed in most plans.

The fad diets promised that the person could eat until full and would not experience hunger. For that to occur, the dieter had to follow diet instructions that included not eating between meals and avoiding all fruit except grapefruit. The diet also limited the consumption of vegetables. The Mayo Clinic fad diet is believed to have originated as the Hollywood diet of the 1930s.

The Hollywood diet

The weight loss plan followed for three weeks consisted of the daily consumption of grapefruit. For 21 days, dieters followed a meal schedule of:

In some versions of the plan, dieters could eat small portions of meat or fish. The daily calories consumed each day totaled less than 800.

The Mayo Clinic diet

The Hollywood diet evolved into the weight-loss plan known as the Mayo Clinic diet or the grapefruit diet. The citrus fruit remained a key element of the numerous versions of the fad diet. Dieters could eat meat and fats, items that were said to produce the sensation of feeling full. Fruits and vegetables were restricted, and the diet was a temporary plan that generally lasted 12 days.

In one version of the diet, people followed this plan:

Some diets allowed fish or poultry. In one version, the dieter ate eggs and grapefruit for every meal for several days. There was no limit on the amount of eggs eaten at lunch, a meal that included spinach. After several days, the dieter could eat pork chops or lamb chops. For some dieters in the 1950s and 1960s, the plan was a steady diet of grapefruit and steak.

Most versions of the Mayo Clinic fad diet are based on a 12-day cycle. For the dieter wanting to lose more weight, the person diets 12 days, takes two days off, and then starts the cycle again. Some plans recommended starting the plan on a Monday so the dieter would have the weekend off to indulge in forbidden items. Some dieters satisfied their cravings for pastries; others enjoyed alcoholic beverages.

The New Mayo Clinic fad diet

The Internet in 2007 was among the sources of the new Mayo Clinic diet, a plan that expanded on the original diet with more food choices. The new version contained the information that the diet was not created by the Mayo Clinic and was not approved by the medical facility. Some sites carried evaluations of the risks and benefits of the diet. Most advised the public to consult a doctor before starting a weight-loss program. Some versions advise people to exercise.

The dieter follows the plan for 12 days and is off the diet for two days. The weight-loss plan consists of:

The vegetables allowed on the diet are red and green onions, red and green bell peppers, radishes, tomatoes, broccoli, cucumbers, spinach, cabbage, lettuce, green beans, chili peppers, cole slaw, and other green vegetables including dill or bread-and-butter pickles. Dieters may also eat cheese, hot dogs, and one tablespoon (28.3 g) of nuts each day. Mayonnaise is also allowed.

Not allowed on the diet are white vegetables such as potatoes and white onions, corn, sweet potatoes, other starchy vegetables, breads, pasta, rice, and snack foods such as potato chips and pretzels. Also forbidden are fruit and desserts.

People are advised to follow all of the diet rules because the combination of food supposedly burns fat. The diet regulations are:

Some versions of the plan advise dieters to drink 64 ounces (1.9 l) of water each day. Diet soda is allowed on some plans. The dieter may not see a weight loss until the fifth day. At that time, the person may lose five pounds (2.27 kg). Furthermore, people may lose about 1 pound (0.45 kg) a day until reaching their goal weights. Supposedly, the diet works because it restricts the amount of sugar and starch that create fat.


People use the Mayo Clinic fad diet because they quickly shed pounds, and that loss affirms the diet's promise that certain foods burn fat. However, the loss of pounds is caused by a restriction on carbohydrates, which are found in breads, vegetables, and fruits. Eliminating or limiting those foods results in fewer calories consumed. Cutting back on calories produces a weight loss. Additionally, eating more protein, foods that are high in fat, creates the sensation of feeling full.


The primary benefit of the Mayo Clinic fad diet is that a person quickly loses weight. For some people, a diet of several weeks is easier to follow than one that could last months or one described as a lifetime of healthy eating. On the fad plan, dieters do not have to count calories or track the fat and fiber content of foods. People follow a plan consisting of several basic foods. The diet is more affordable than some weight-loss plans that require the purchase of meals.

Furthermore, dieters could feel that they are not depriving themselves because they are allowed to eat as much as they want of meat and other high-fat proteins. People fond of fried foods will be happy that they do not have to give up those items.

The plan consists of a limited selection of food so it will be easy for dieters to shop and to know what to eat. While the repetitive nature of the diet may become monotonous, that sameness may help curb dieters' appetites. The monotony for some dieters is endured by the knowledge that the diet is short-term.


People taking certain medications should not prescribe to the Mayo Clinic fad diet because grapefruit and grapefruit juice could interact with those medications. Moreover, the general public should avoid the popular diet because it is not nutritionally balanced. According to the Mayo Clinic, the fad diet could be dangerous because some versions restrict calorie consumption to 800 per day.

Organizations including the clinic and the American Heart Association maintain that 1,200 calories per day is the minimum amount that should be consumed unless a dieter is following a medically supervised weight-loss plan.

Some versions of the diet are low calorie; others permit the dieter to eat unlimited amount of proteins. The fad diet severely restricts other food groups. Dieters miss out on the nutrients and fiber in fruits and vegetables, and the calcium found in dairy products. At the same time, they eat foods that often contain more calories, fat, and sodium.

The appeal of the Mayo Clinic fad diet is that it is a short-term plan. However, people often gain back more weight after they stop dieting.


Risks associated with the fad diet range from the medication-grapefruit interaction to the potential for complications related to a high-fat diet. The Mayo Clinic in 2006 cautioned that chemicals in grapefruit and grapefruit juice interfere with the body's process of breaking down drugs in the digestive system. The interference could produce excessively high levels of the drug in the blood. The interaction could occur with some medications to treat high blood pressure, HIV, high cholesterol, arrhythmia (abnormal heart rhythm), and erectile dysfunction. There is also a potential for interaction with some anti-depressants, anti-seizure medications, tranquilizers, immunosuppressant drugs and the pain relief drug Methadone.

The issue of this interaction was subject to some debate, with the Florida Department of Citrus in 2003 advising the public that the use of alternate medications would allow people to continue drinking grapefruit juice. In a related matter, the University of Florida served a key role in the establishment in 2003 of the Center for Food-Drug Interaction Research and Education. The center focuses on interactions with grapefruit. It is accessible to the public through a website.

People with concerns about grapefruit should ask their physician or pharmacist about possible drug interactions or alternative medications.

Furthermore, the combination of a high-protein diet with unlimited fat and the restriction on carbohydrates puts dieters at risk for conditions such as high blood pressure, heart disease, strokes, and diabetes. According to the American Heart Association, the risk is caused by increased cholesterol levels. This rise in cholesterol is brought on by the increase in fat and the decrease in fiber from fruits, vegetables, and wholegrain products. These foods are complex carbohydrates, and eliminating them causes the body to burn stored fat. While this process causes a weight loss, it triggers a reaction called the “starvation mode.”

The nutritional term for a kilocalorie, the unit of energy needed to raise the temperature of one liter of water by one degree centigrade at sea level. A nutritional calorie equals 1,000 calories.
A nutrient that the body uses as an energy source. A carbohydrate provides 4 calories of energy per gram.
A fatty substance found in each cell of the human body and in animal foods.
A nutrient that the body uses as an energy source. Fats produce 9 calories per gram.
A complex carbohydrate not digested by the human body. Plants are the source of fiber.
A nutrient that the body uses as an energy source. Proteins produce 4 calories per gram.
Serum cholesterol—
Cholesterol that travels in the blood.
Trans fats—
Short for trans fatty acids, they are also known as a partially hydrogenated oils. The acids are formed when hydrogen is added to liquid vegetable oils to make them more solid.

When the person ends the diet and again eats carbohydrates, the body responds by converting food into fat. This protection against starvation results in a weight gain.

Research and general acceptance

Grapefruit is a source of vitamin C and fiber, but the citrus fruit does not have the capacity to burn calories. That's one of the misconceptions about the fad diet that the Mayo Clinic called a “hoax” because it limits the variety of food and promises a dramatic weight loss. Research by the clinic and organizations including the United States Department of Agriculture (USDA) concluded that a healthy weight loss is based on a nutritionally balanced diet with selections from the five food groups.


Moreover, much of the Mayo Clinic fad diet conflicts with the American Heart Association's “Diet and Lifestyle Recommendations.” The nutritional guidelines for preventing cardiovascular disease include a diet of:

The American Heart Association and other organizations recommend that people exercise regularly, usually from 30 to 60 minutes most days of the week.

General acceptance

Versions of the Mayo Clinic fad diet have been in circulation since the 1930s. The weight loss plan's popularity was related to the fact that people rapidly lost weight by eating foods not ordinarily on a diet. The popularity of the diet seemed to lessen when the public discovered the Atkins diet, a weight-loss plan with some similarities.

See also Diet apps ; eDiets ; Fad diets .



U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015–2020 Dietary Guidelines for Americans. 8th ed. December 2015. (accessed May 1, 2018).

Zeratsky, Katherine. “Consumer Health Expert Answers: ‘I Like to Drink Grapefruit Juice but Hear that It Can Interfere with Some Prescription Medications. Is That True?’” . (accessed April 11, 2018).

Liz Swain

  This information is not a tool for self-diagnosis or a substitute for professional care.