Everything You Need to Know About the Grapefruit Diet

by Marixie Ann Obsioma, MT, undergrad MD on August 25, 2021
Last updated on August 25, 2021

We all want to look slim to wear a beautiful outfit to an upcoming event. If you want to shred a few extra pounds fast, you should pay attention to the grapefruit diet. Some say it will give you amazing results, boost your immune system and improve metabolism.

Everything You Need to Know About the Grapefruit Diet

However, it is important to remember that there is no one-size-fits-all approach to a healthy lifestyle. Successful eating plans need to be individualized and take the whole person into consideration. Prior to starting a new diet plan, consult with your healthcare provider or a registered dietitian, especially if you have an underlying health condition.

In this article, we would like to tell you about the benefits of the consuming grapefruit for overall health and its effects on weight.

What is the Grapefruit Diet?

The grapefruit diet, sometimes called the “Hollywood Diet,” has been around since the 1930’s. There are variations of the diet, but eating half a grapefruit prior to each meal to lose weight is the premise. At least two studies have been done to specifically test the effectiveness of grapefruit on weight loss. One study of obese patients does suggest that eating grapefruit or drinking grapefruit juice before meals may assist weight loss (1).

However, a more recent grapefruit study suggests that consumption of any low-energy-dense food (i.e. foods that are low in calories but high in water) 20 minutes prior to a meal, coupled with a calorie-restricted diet, can be a great weight-loss strategy (2).

4 Ways A Grapefruit May Help You Lose Weight

1. It’s Low in Calories, Yet High in Nutrients

Grapefruit is an incredibly healthy food to include in your diet. That’s because it’s high in nutrients, but low in calories. In fact, it’s one of the lowest-calorie fruits.

It provides a decent amount of fiber, in addition to more than 15 beneficial vitamins and minerals.

Additionally, it is a rich source of some powerful antioxidant plant compounds, which are likely responsible for many of its health benefits.

2. May Control Appetite

Grapefruit contains a decent amount of fiber — 2 grams in half of a medium-sized fruit.

Research shows that a diet high in fiber-rich fruits is beneficial for inducing feelings of fullness. This is because fiber slows the rate at which your stomach empties, increasing digestion time (34).

Thus, consuming adequate amounts of fiber may automatically help you eat fewer calories throughout the day by keeping your appetite at bay (5).

3. It Has Nootkatone, Naringenin, and Lycopene

Exciting preliminary evidence from Japan shows that a compound called nootkatone, which helps create grapefruit’s aroma, may significantly reduce hunger and can stimulate metabolism and ramp up weight loss.

Nootkatone is so promising that it has garnered the attention of pharmaceutical companies. However, experts say whole grapefruit may offer more benefits than a supplement. Credit goes to a host of slimming compounds, including a hefty dose of vitamin C, which is linked to a 20 percent faster metabolism.

Findings also hint that an antioxidant in grapefruit called naringenin may act like lighter fluid in the liver, prompting the organ to burn fat faster. And per the journal Nutrition, lycopene, a pigment in pink and red grapefruit, raises levels of a belly-flattening hormone called adiponectin.

4. Lowers Insulin Level

Evidence from the famous Scripps Clinic found that nutrients in grapefruit, including all of its antioxidants and fiber, dramatically lower levels of the hormone insulin, helping regular grapefruit eaters lose up to 500 percent more weight than those who skip the fruit, making it essential to any longevity diet.

How Effective is the Grapefruit Diet?

Although claims of some magical fat-burning enzyme in grapefruits aren’t backed by research, studies have found grapefruit to be positively associated with weight loss.

One study found that participants who consumed grapefruit daily with meals experienced reduced waist size (6).

A 2014 study found that body weight, waist circumference, and body mass index (BMI) were lower among female grapefruit consumers when compared to non-consumers (7).

More current research is needed to determine the connection between grapefruit consumption and weight loss.

Although quick and temporary weight loss is possible on the grapefruit diet, it’s probably due to the fact that you’re consuming less than 1,000 calories a day (8).

Promises of losing 10 pounds in 12 days is unrealistic and unsustainable.

You may initially lose weight on this diet. But studies show that low calorie diets rarely keep weight off for good (910).

Are There Any Side Effects?

Although grapefruits are a low calorie, nutrient-dense option with many health benefits, this diet is problematic for other reasons.

There’s no evidence of magical fat-burning enzymes associated with grapefruits.

Quick, temporary weight loss associated with the grapefruit diet is likely due to the low calorie and low carb intake. This would result in quick, temporary weight loss even without the grapefruit.

While low-calorie diets may result in initial weight loss, they’re rarely successful for those seeking long-term results.

There are health drawbacks, too.

It’s very restrictive. It 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). Low calorie diets can weaken your bones, lower your metabolism, and cause fatigue, muscle loss, and nutrient deficiencies.

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.

Twelve days on such a restricted plan may be possible, but eating the same foods and such few calories every day could lead some people to ultimately abandon the plan.

The grapefruit diet is also ambiguous. With multiple versions, it’s bound to cause confusion among followers.

The grapefruit diet 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.

What to Eat


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).


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.

What Not to Eat

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.


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.

Sample Weight Loss Plan

Day 1

Breakfast: one grapefruit, a slice of whole-grain toast with cream cheese.

Snack: a cup of steamed broccoli.

Lunch: a bowl of tomato soup and half a grapefruit.

Snack: half a cup of tuna and a slice of cheese.

Dinner: a grapefruit and a cup of cottage cheese.

Day 2

Breakfast: one grapefruit and a homemade muesli bar.

Snack: a cup of blueberries.

Lunch: grilled chicken breast with herbs and garlic.

Snack: half a grapefruit.

Dinner: half a grapefruit and a cup of coconut milk.

Day 3

Breakfast: one grapefruit and oatmeal with almond milk.

Snack: a green apple.

Lunch: zucchini noodles and grilled tofu.

Snack: ten almonds.

Dinner: one grapefruit and green beans.

Other Tips to Add Grapefruit to Your Diet

  1. Peel and eat for a quick and easy snack on the go!
  2. Toss with cooked shrimp and fresh avocado into a salad to add an exotic twist
  3. Add slices to yogurt for a light snack or breakfast
  4. Mix juice into sauces for a sweet and tangy twist
  5. Chop into vinaigrettes, sauces and relishes
  6. For a summer salsa, dice with cilantro and chili peppers and serve over poultry or fish – or even with chips for a party snack

Other Health Benefits of Grapefruit

1. Boosts Your Immune System

Eating grapefruit regularly may be beneficial for your immune system.

It’s prized for its high content of vitamin C, which has antioxidant properties known to protect your cells from harmful bacteria and viruses.

Additionally, several studies have shown vitamin C to be beneficial for helping people recover more quickly from the common cold (1112).

Many other vitamins and minerals found in grapefruit are known to benefit immunity, including vitamin A, which has been shown to help protect against inflammation and several infectious diseases.

Grapefruit also provides small amounts of B vitamins, zinc, copper and iron, which all work together in the body to promote immune system function. They also help maintain the integrity of your skin, which acts as a protective barrier to infection.

2. Promotes Heart Health

Regularly consuming grapefruit is thought to improve heart health by reducing risk factors for heart disease, such as high blood pressure and cholesterol.

People who ate grapefruit three times daily for six weeks experienced significant reductions in blood pressure over the course of the study. They also showed improvements in total cholesterol and “bad” LDL cholesterol levels (6).

These effects are likely due to the important nutrients that grapefruit contains, which play a role in keeping your heart functioning properly.

First, grapefruit is fairly high in potassium, a mineral responsible for many aspects of heart health. Half a grapefruit provides about 5% of your daily potassium needs.

Adequate potassium intake is associated with a reduced risk of high blood pressure. Additionally, it has been shown to lower the risk of death from heart disease.

Second, the fiber in grapefruit may also boost heart health, given that a high fiber intake is associated with lower blood pressure and cholesterol levels.

Overall, researchers claim that including fiber and antioxidant-rich fruits like grapefruit as part of a healthy diet helps protect against conditions like heart disease and stroke (1314).

3. Lowers Blood Pressure

Grapefruit has got some data that it decreases systolic blood pressure, not by a lot. It’s usually about five points, but there’s definitely good data. And for the 70 million Americans who have, any drop in blood pressure is a good drop.

The effect on blood pressure may be due to grapefruit’s high potassium levels. Potassium neutralizes the negative effects of sodium.

But again, don’t eat grapefruit if you are already taking a blood-pressure lowering drug. Certain ones, such as Procardia and Adalat CC (both are from the generic nifedipine), can be dangerous when combined with grapefruit.

4. Very Hydrating

Grapefruit contains a lot of water and is, therefore, very hydrating. In fact, water makes up most of the fruit’s weight.

There are almost 4 ounces (118 ml) of water in half of a medium grapefruit, which accounts for about 88% of its total weight.

While drinking lots of water is the best way to stay hydrated, eating water-rich foods can also help.

5. Speeds Up Wound Healing

Vitamin C helps form healthy scar tissue and new blood vessels, both of which help return your body to a healthy state. A grapefruit contains about 72 mg of vitamin C, which is 120% of the daily value.

Vitamin C speeds up wound healing post surgically. Some experts ask people are asked to 500 milligrams of vitamin C before they go into surgery.

Always ask your doctor before adding vitamins, minerals, or any herbal supplements to your daily regimen, especially if you’re about to have surgery.  In this case, that goes for grapefruit too, given its ability to affect the metabolism of certain drugs.

6. Reduces the Risk of Kidney Stones

Consuming grapefruit may reduce your risk of developing kidney stones, which result from a buildup of waste materials in the kidneys.

These waste materials are products of metabolism that are normally filtered through the kidneys and removed from the body in urine.

However, when they crystallize in the kidneys, they become stones. Larger kidney stones may cause a blockage in the urinary system, which can be incredibly painful.

The most common type of kidney stones is calcium oxalate stones. Citric acid, an organic acid found in grapefruit, may be effective at preventing them by binding with calcium in the kidneys and flushing it out of the body.

Also, citric acid has the ability to increase the volume and pH of your urine, producing an environment that is less favorable to the formation of kidney stones.

7. Possibly Prevent Cancer

A large study conducted in Japan found that people who ate citrus, including grapefruit, throughout the week had a lower risk of developing cancer, especially and pancreatic, compared with the total group of participants.

The effect was amplified among those who also drank a lot.

The authors speculate that compounds in citrus fruits and stop cancer cells from multiplying. They may also help repair damaged DNA, which contributes to the development of tumors.

The fiber in grapefruit may also help prevent while fruits high in vitamin C and beta-carotene, which is in pink and red grapefruit, may lower the risk of.

Key Takeaway

While the “grapefruit diet” is not ideal for everyone, grapefruit is a nutritious, low-calorie choice. If you are taking medications, you will need to be aware of how much grapefruit you eat. As mentioned above, some medications that are used to treat thyroid conditions, high cholesterol, and depression can interact with grapefruit and cause adverse side effects.

In general, try to follow 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 balance everything.

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. Be informed and know your nutritional needs as well to be able to set the right weight loss plan and goals.

Aside from weight loss, there are also several 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.


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