What Is the Grapefruit Diet?

The grapefruit diet is a fad diet that has been around since the 1920s and 1930s (possibly earlier). The restrictive eating plan is widely believed to be a byproduct of the Depression Era when it became trendy among actresses, eventually becoming known as "The Hollywood Diet."

The grapefruit diet saw a resurgence in the 1970s, and various iterations of the diet continue to circulate. Over the years, it also became associated (incorrectly) with the Mayo Clinic. In 2004, a book titled "The Grapefruit Solution" suggested that eating grapefruit could improve the success rate of the weight loss plan of your choice.

The focus of any version of the grapefruit diet generally involves eating a few servings of grapefruit a day and tends to be extremely restrictive with other foods. The biggest promise of the grapefruit diet is significant weight loss in a short period of time.

While it's true that grapefruit is a nutritious fruit, it does not necessarily have any magical powers to rev up weight loss.

What Can You Eat?

While many versions of the diet exist, the grapefruit diet's basic premise is consuming grapefruit (typically the whole fruit, though some versions allow for powdered grapefruit supplements) before all three meals a day, for a duration of seven to 10 days or more. Also, there is a restrictive eating plan for those three meals.

While there can be some variation in the grapefruit diet instructions, all call for eating the grapefruit (or drinking grapefruit juice) before meals, most versions consistently call for three meals a day, no snacks, and a fourth meal (or bedtime snack)—usually a glass of skim milk or tomato juice.

What You Need to Know

While nutrition experts don't recommend the grapefruit diet, it can be especially problematic for people who take certain medications as consuming grapefruit (especially frequently or in large amounts) with certain medicines can have adverse health effects.

More than 50 medications are known to interact with grapefruit, but some of the most common medications that are not safe to mix with grapefruit or grapefruit juice include:

• Thyroid medications: People on thyroid hormone replacement therapy need to avoid consuming too much grapefruit, which can make thyroid medications less effective.
• Statins: Statin medications—including Lipitor (atorvastatin), Zocor (simvastatin), and Mevacor (lovastatin)—are prescribed to treat high cholesterol, and grapefruit can change the levels of these medications in the blood, as well as increase the likelihood of side effects.
• Antidepressants: Several medications used to treat depression, bipolar disorder, and other mental health conditions can be affected by certain enzymes in grapefruit.

Grapefruit

As the cornerstone of this diet, the serving size is half a grapefruit or 8 ounces of grapefruit juice. You can also purchase powdered grapefruit in capsule form. For any of these choices, you consume the grapefruit before the rest of the meal.

Eggs and Bacon

Some forms of the grapefruit diet suggest eating two eggs and two strips of bacon every day for breakfast (after the grapefruit).

Meat

Lunch and dinner on the grapefruit diet consist of a serving of meat along with a salad. The diet makes no distinction between lean proteins and those with lots of saturated fat. It also doesn't limit portion size.

Salad and Cooked Vegetables

Your choice of meat is paired with a salad or some cooked veggies (some versions specify red or green vegetables only). In most cases, any kind of salad dressing is permitted.

Other Fruits

Some versions of the grapefruit diet allow for other fruit choices, while others do not.

Grains, Starches, and Added Sugars

All grains, starches, and added sugars are excluded from the grapefruit diet, making it very restrictive.

Beverages

The grapefruit diet encourages water and allows for a cup or two of tea or coffee per day, but no other beverages.

Dairy Products

Some versions of the grapefruit diet allow for one 8-ounce glass of skim milk per day. Other than that, no dairy products are permitted.

Pros and Cons

Though grapefruit is a nutritious food, a restrictive eating plan that consists of mostly grapefruit eliminates other healthy food groups that are part of a balanced diet.

Pros

Beneficial Nutrients

Adding grapefruit to your regular diet can offer some benefits but probably does not directly lead to weight loss. Rather, adding more fruits and vegetables like grapefruit to your diet may aid in weight loss.

Studies have shown that people who consume more fruits and vegetables can eat more volume of food and feel full sooner, and therefore eat fewer calories which may result in weight loss. The fruit is an excellent source of vitamins A and C and the antioxidant lycopene and some flavonoids.

Compared to other fruits, grapefruit is low-calorie and lower in carbohydrates. A full serving of grapefruit (154 grams) has about 2.5 grams of naturally occurring dietary fiber.

Grapefruit is a filling low-calorie, snack. Between the sour taste and the time it takes to peel them, you also can't mindlessly munch your way through several hundred calories' worths of grapefruit the way you might with other snacks.

Cons

Very Restrictive

The grapefruit diet is deficient in calories and far too restrictive to be considered healthy for the long term. It excludes almost all carbohydrates and many nutritious foods (such as whole grains and other fruits). Following the diet might also lead to consuming excessive saturated fat since it suggests eating meat twice a day without any recommendation to favor lean proteins.

False Assumptions

One common belief about grapefruit is that it contains a special enzyme that helps burn fat. This is not true. Eating any fruit before a meal could help with weight loss because it reduces your hunger and could curb the total calories you consume. 

Another false argument for the grapefruit diet is that grapefruit is a "negative calorie" food—meaning that you burn more calories chewing and digesting it than it contains. When you burn more calories than you consume, you lose weight. Therefore, the argument is that eating a negative-calorie food would help with weight loss. Grapefruit does contain a relatively small number of calories, but it does not have a "negative calorie" effect.

Is the Grapefruit Diet a Healthy Choice for You?

The grapefruit diet shares many characteristics with other restrictive fad diets that claim to offer quick and easy weight loss, such as the egg diet and the three-day military diet. However, the grapefruit diet contains a kernel of useful advice for people looking to lose weight.

The U.S. Department of Agriculture's (USDA) dietary guidelines suggest consuming a balanced diet of fruits, vegetables, grains, proteins, and dairy products. The USDA recommends consuming roughly 1,600 to 2,400 calories for women and 2,000 to 3,000 calories per day for men for weight maintenance. This calorie level, and the calorie level you require for weight loss, can vary significantly based on age, sex, weight, and level of physical activity. If you're interested in determining your own calorie guidelines, you can use this calculator.

Health Benefits

A 2006 study showed that eating grapefruit could lower blood sugar and, for some, lead to weight loss. Participants who ate half a grapefruit before meals for 12 weeks lost significantly more weight than a non-grapefruit-eating control group.

However, a third of the participants showed no change in weight after a six-week dietary intervention (eating half of a fresh grapefruit three times a day). Still, there were some decreases in blood pressure and cholesterol levels in this group.

While proponents of the grapefruit diet claim that it will lead to quick weight loss, research supports that weight loss resulting from similar fad diets is often not sustained and that a grapefruit diet could encourage unhealthy eating habits.

Health Risks

Eliminating healthy foods like all grains could result in deficiencies in B vitamins and trace minerals, more common in those people who follow restrictive diets. Additionally, grapefruit can interfere with many commonly used medications.

Despite the small studies that show some weight loss effects with grapefruit, there is very little high-quality research (large, randomized studies in humans) that supports this claim. Subsisting on mostly grapefruit, protein, and some vegetables is neither a nutritionally balanced nor sustainable weight loss plan.

A Word From Verywell

While the grapefruit diet commonly found online is not a healthy diet plan, adding more grapefruit to your diet might be—especially if you are trying to lose weight. The fruit is a nutritious, low-calorie choice. If you are taking medications, however, you will need to be aware of how much grapefruit you eat. Some medications that are used to treat thyroid conditions, high cholesterol, and depression can interact with grapefruit and cause adverse side effects.

In general, look for an eating plan that doesn't cut out major food groups, offers the potential for slow and steady weight loss, and addresses your health goals while also being safe. Your doctor or a registered dietitian can help you find a diet that is safe and effective.

Remember, following a long-term or short-term diet may not be necessary for you and many diets out there simply don’t work, especially long-term. While we do not endorse fad diet trends or unsustainable weight loss methods, we present the facts so you can make an informed decision that works best for your nutritional needs, genetic blueprint, budget, and goals.

If your goal is weight loss, remember that losing weight isn’t necessarily the same as being your healthiest self, and there are many other ways to pursue health. Exercise, sleep, and other lifestyle factors also play a major role in your overall health. The best diet is always the one that is balanced and fits your lifestyle.