21 Day Grapefruit Diet

Looking for a new diet plan? The grapefruit diet has been around since the 1930s — and it's just as popular today as it was decades today. Several versions exist, but they all have one thing in common: dieters must restrict calories and eat grapefruit at each meal, along with a limited variety of foods like bacon and eggs. Unfortunately, weight loss isn't that simple.

The Grapefruit diet has been around for a long time.
Image Credit: Julie Rideout/Moment Open/GettyImages


The 21-day grapefruit diet involves eating grapefruit with every meal for three weeks. Most versions of this slimming plan limit calories and food choices, which may lead to nutrient deficiencies.

Grapefruit, though, is high in fiber and suppresses hunger, making weight loss easier. Consume it as part of a balanced diet to reap its benefits.

Does the Grapefruit Diet Work?

Numerous studies conducted over the years confirm the health benefits of grapefruit. With only 65 calories per serving, this citrus fruit fits into any diet. It's juicy and refreshing, offering both flavor and nutrition.

A May 2014 review published in Food & Nutrition Research has linked grapefruit consumption to higher nutrient intakes. Women who consumed this fruit or drank its juice regularly had a smaller waist circumference and lower body mass index and body weight. Their triglyceride levels were lower and HDL ("good") cholesterol levels were higher compared to non-consumers. The grapefruit group also had higher intakes of vitamin C, potassium, magnesium, fiber and beta-carotene.

Grapefruit consumption has been also shown to lower C-reactive protein, a marker of inflammation, according to the Food & Nutrition Research review. These potential benefits could be due to the vitamins, minerals and phytochemicals in grapefruit. This citrus fruit is a good source of flavonoids, especially naringin, as well as carotenoids, vitamin A and electrolytes. However, no association was found between grapefruit consumption and the risk of being obese or overweight.

Some studies suggest that grapefruit may facilitate weight loss, but none actually mention the grapefruit diet. Additionally, most research has been conducted on animals, so the results may not apply to humans.

For example, a small study published in the July 2012 edition of the journal Metabolism: Clinical and Experimental assessed the effects of grapefruit consumption on body weight, blood pressure and blood lipids. The subjects who ate grapefruit with each meal for six weeks experienced a reduction in blood pressure, cholesterol levels and waist circumference but modest weight loss. The differences between grapefruit consumers and non-consumers were negligible. (Note that this was a small study of just 74 participants, so its results cannot necessarily be assumed to apply to a larger population.)

Up to date, there are no studies supporting the 21-day grapefruit diet and its impact on health or body weight. A brief description of this weight loss plan is provided by the Winchester Hospital. The grapefruit diet and its countless versions involve eating grapefruit or drinking its juice at every meal.

Basics of the Grapefruit Diet

Dieters are allowed to have three or four daily meals, which may consist of grapefruit and high-protein foods, such as bacon, eggs, meat or skim milk. Some versions allow the consumption of coffee, salad and tomato juice. Others limit food intake to 800 to 1,000 calories a day. The rules are not set in stone — it all comes down to which version of the diet you follow.

If you're planning to try the 21-day grapefruit diet, you must limit your calorie intake and eat grapefruit at every meal for three weeks. Some versions are more flexible than others, as they allow dieters to eat nonfat plain Greek yogurt, low-fat cheese, cottage cheese, fish, whole wheat English muffins or strawberries. There are also versions that restrict carbs and encourage the consumption of high-fat foods.

Read more: The Most Dangerous Diets Ever

Its proponents say that grapefruit contains fat-burning enzymes and that you can lose up to 10 pounds in 12 days or so. However, these claims lack scientific evidence. Even if you do lose weight, it's likely because you're eating less.

Does Grapefruit Burn Belly Fat?

Contrary to what you may have heard, this citrus fruit doesn't burn belly fat — or any type of fat. It can improve your health, though. Grapefruit is chock-full of vitamins, minerals and antioxidants, making it easier to meet your nutritional needs. It also contains dietary fiber, which may suppress hunger and improve appetite control.

One serving of grapefruit provides 2.5 grams of fiber — that's about 7 percent of the daily recommended intake. According to a February 2015 review published in the Annals of Internal Medicine, eating more fiber can make weight loss easier, especially for those who find it difficult to follow traditional diets.

Read more: 9 Strategies to Make Your Diet Resolutions Stick

This nutrient promotes satiety and keeps your digestive system running smoothly. Unlike other carbs, it doesn't increase blood sugar levels. As the Academy of Nutrition and Dietetics points out, higher fiber intakes may reduce the risk of type 2 diabetes, heart disease, elevated cholesterol and colorectal cancer.

Grapefruit doesn't burn fat, but it can help reduce your food intake by keeping you full longer. This fruit is over 88 percent water, which further enhances its ability to suppress appetite. Naringin, a flavonoid in grapefruit, may facilitate fat loss, although more research is needed in this area.

A review published in the journal Phytotherapy Research in February 2015 suggests that naringin may improve glucose tolerance and insulin sensitivity. According to the same source, this compound stimulates thermogenesis, increasing energy expenditure. Additionally, it exhibits anti-inflammatory properties. These effects were observed in animal studies, though, so they may not be relevant to humans.

Lose Weight With Grapefruit

This citrus fruit may or may not help you lose weight — it all comes down to your eating habits. If your diet consists of junk food, eating grapefruit is unlikely to make any difference in terms of weight loss. Enjoy it as part of a balanced diet and incorporate exercise in your daily routine to lose stubborn fat.

One serving of grapefruit provides 63 percent of the daily recommended vitamin C intake. It's also an excellent source of vitamin A, copper, potassium and other essential nutrients. Plus, it has only 13.4 grams of carbs, which makes it suitable for ketogenic and low-carb diets.

Consume this fruit in the morning, between meals or after exercise to fuel your body. Use it as a substitute for high-calorie snacks like bagels, pretzels, chips or cookies. If you like its flavor, by all means, eat it! It's low in calories and carbs, high in fiber and loaded with antioxidants.

Read more: 15 Tips From Real People Who Succeeded at Losing Weight

Forget about the grapefruit diet, though. This weight loss plan isn't just restrictive and difficult to follow, but it may also lead to nutrient deficiencies. As the American Academy of Family Physicians points out, fad diets provide only temporary results, causing muscle and water loss, not fat loss. Most dieters gain back the lost weight — and even more.

Also, beware that grapefruit and its juice may interact with certain medications, according to the FDA. This citrus fruit may interfere with statin drugs, corticosteroids, anti-anxiety meds, antihistamines, antihypertensives and others. If you're taking any of these drugs, consult your doctor before incorporating grapefruit into your diet.

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