The unofficial Mayo Clinic grapefruit diet is a strict, short-term, rapid weight-loss plan that wasn't actually developed or endorsed by the Mayo Clinic. In fact, it's just another fad diet that has been criticized for being both unhealthy and unsustainable.
What Is the Grapefruit Diet?
The unofficial Mayo Clinic grapefruit diet consists of a strict daily menu and guidelines, and supporters claim that you can lose up to 50 pounds in 10 weeks.
As you might guess from the name, grapefruit is a major feature of the diet. The sour citrus has been touted for decades as a dieter's friend, supposedly helping to burn fat or speed metabolism. But there aren't any credible scientific studies to support this myth.
For breakfast each day, you are instructed to eat two eggs, two slices of bacon and either 4 ounces of grapefruit juice or half of a grapefruit. Lunch consists of unlimited salad with a full-fat dressing of your choice, more grapefruit or grapefruit juice and any type of meat, fish or poultry in any amount and prepared in any way. Dinner is similar to lunch, but with vegetables substituted for the salad and, again, with the stipulation that the foods can be eaten in unlimited amounts. You're allowed a before-bedtime snack of either a glass of non-fat milk or tomato juice.
Why It’s Not a Good Idea
Fast weight loss can be dangerous. It takes time to lose weight safely, and as a general rule of thumb, you should aim to lose 1 to 2 pounds a week, according to the Mayo Clinic. Fad diets like this one do more harm than good, since their success is only based on weight loss, not fat loss. As a result, they cause dehydration and a decrease in muscle mass, according to the American Academy of Family Physicians. This may cause the number on the scale to drop initially, but you're very likely to gain that back as soon as you start eating normally again. And if you've lost muscle mass, it may be harder to lose weight down the road, since muscle burns more calories than fat.
Restrictive diets have negative side effects. "When diets are so restrictive, not only will they cause nutrient deficiencies, but they're also not sustainable," Katherine Zeratsky, RD, LD, a registered dietitian with the Mayo Clinic, tells LIVESTRONG.com. "If a diet promises something that's too good to be true, chances are you won't be able to maintain the weight loss."
Long term, a high-protein, low-carb, low-fiber plan like the grapefruit diet can also lead to problems such as bad breath, headache and constipation, and the risk of heart disease increases, according to the Mayo Clinic.
Grapefruit isn't a magic bullet. The effects of grapefruit consumption on body fat, weight and blood pressure were evaluated in a small study published July 2012 in Metabolism. The researchers concluded that those who ate grapefruit with each meal for six weeks experienced only modest weight loss — 1.3 pounds, more or less — and a reduction in waist circumference, blood pressure and cholesterol levels. But differences in the grapefruit-consuming group were not significant when compared with people on a controlled diet. So the real reason behind rapid weight loss on the grapefruit diet is likely not the grapefruit itself, but the fact that the diet is so low in calories.
Some people should not eat grapefruit. Lastly, take caution when eating grapefruit or drinking grapefruit juice and taking certain prescription medications, warns the Food and Drug Administration. The juice can block the breakdown of some drugs, like statins, hindering their effectiveness but also causing them to accumulate in the body, which can be dangerous.
A Smarter Way to Slim Down
The most effective diet for both sustainable weight loss and enhanced health is one that emphasizes a wide variety of fruits and vegetables, whole grains and low-fat protein sources as well as regular exercise. That's the idea behind the real Mayo Clinic Diet. No foods are banned; instead, the program aims to help followers make better food choices, learn portion control and stay active.
"We believe that the (real) Mayo Clinic Diet isn't even a diet — it's a lifestyle approach that warrants behavioral changes for long-term sustainability," says Zeratsky. "We, at the Mayo Clinic, want people to eat a variety of foods in each food group in a way that fits their customary patterns and that meets their nutritional needs — foods that they enjoy and foods that are nutritious."
- Freedieting: "Mayo Clinic Diet"
- American Academy of Family Physicians: "Nutrition for Weight Loss: What You Need to Know About Fad Diets"
- Mayo Clinic: "Are High-Protein Diets Safe for Weight Loss?"
- Metabolism: "The Effects of Daily Consumption of Grapefruit on Body Weight, Lipids, and Blood Pressure in Healthy, Overweight Adults"
- Food and Drug Administration: "Grapefruit Juice and Some Drugs Don't Mix"
- Mayo Clinic: "The Mayo Clinic Diet: A Weight-Loss Program for Life"
- Mayo Clinic: "Why do doctors recommend a slow rate of weight loss? What's wrong with fast weight loss?"