What is it?

The grapefruit diet is a protein-rich meal plan with a primary focus of grapefruit or grapefruit juice at every meal. Used for more than 80 years, the diet's goal is quick weight loss—it's a 12-day plan. While several versions of the diet exist, the majority of them include a daily caloric intake of less than 1,000 calories.

Under the guidelines of the diet, the foods can be prepared with as many spices, salad dressings, or butter as the person would like. Some caveats of the diet include no extremely hot or extremely cold foods, nothing prepared in aluminum pans, and keeping "protein meals" and "starch meals" at least four hours apart.

Examples of the meals include:

  • Breakfast: Two boiled eggs, two slices of bacon, and ½ grapefruit or 8 ounces of grapefruit juice.
  • Lunch: Salad with dressing, any meat in any amount, and ½ grapefruit or 8 ounces of grapefruit juice.
  • Dinner: Any kind of meat prepared any way, salad or red and green vegetables, coffee or tea, and ½ grapefruit or 8 ounces of grapefruit juice.
  • Bedtime Snack: 8 ounces of skim milk.

The Promise

The grapefruit diet promises quick results—as much as losing up to 10 pounds in 12 days—due to fat-burning enzymes found in grapefruits. It promises these results without starvation and eating normal meals at normal times.

Pros & Cons

The biggest pro of the diet is its results. Many people have found the quick weight loss results encouraging, especially for special events where they want to look their best. Many have found it useful as a kick-start to find another program to keep the weight loss going after the 12-day diet is over.

Also, incorporating low-calorie, highly nutritious foods like grapefruit is a smart and healthy choice not only for weight loss, but for overall general health. The vitamin C alone is great protection for the immune system.

However, the claims of some magical fat-burning enzyme aren't backed by any research. The core of the diet is the low-caloric intake, which would result in quick, temporary weight loss even without the grapefruit. Weight loss of 10 pounds in 12 days is unrealistic and could very likely include loss of water and muscle and possibly some fat. 

While grapefruit juice and fresh grapefruit can be part of a balanced, healthy diet, according to the Food and Drug Administration (FDA), they can also interfere with certain medications, including:

  • some statin drugs (used to lower cholesterol), including Lipitor, Zocor, and Pravachol
  • nifedipine, a blood pressure medication
  • some antihistamines, such as Allegra
  • certain antianxiety drugs, including BuSpar
  • some organ transplant rejection drugs
  • amiodarone, an anti-arrythmia drug

Grapefruit juice tends to interfere with the action of these drugs. For example, drinking grapefruit juice while taking statins increases the absorption of the drug into the bloodstream. Higher concentrations of these drugs in your blood can increase your risk for adverse complications, including liver and kidney problems. For other drugs, such as antihistamines, grapefruit juice can reduce the amount of the drug that is absorbed, thereby reducing the drug's effectiveness. Ask your doctor or pharmacist if you can have fresh grapefruit or grapefruit juice while taking these and other medications. (FDA, 2012)

Another negative aspect of the diet plan is its limitations in scope. Twelve days on such a restricted plan may be possible, but eating the same foods every day could lead some people to ultimately abandon the plan.

Healthline Says

Any misconceptions about grapefruit should be cleared up: Outside of one small study, there is no evidence to suggest there is any magical power found in grapefruit outside the fact it is a low-calorie, highly nutritious citrus fruit.

The only real benefit to this diet could be if you're looking to quickly slim down for vacation to Cancun or for an upcoming high school reunion, but the weight will return nearly as quickly as it left. The weight that is lost under the diet is what is known as "water weight" because of the low caloric intake. It's a quick fix without any real potential of long-term sustainability, and it's not especially healthy.

A diet so limited in its scope would be almost impossible to commit to in the long-term. With so many foods excluded, it is highly unlikely that the mundane, repetitive nature of the diet would have any long-term followers, plus the fact that not very many people love grapefruit enough to eat it several times per day! In addition, most salad dressing and meats—especially the daily morning bacon—are high in saturated fats and cholesterol, so while the quick weight loss might feel and look nice, the grapefruit diet can do more long-term damage than good.

Grapefruits are good. The grapefruit diet isn't.

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