The Grapefruit Diet is a protein based diet that focuses on consuming at least 1 grapefruit or 1 cup of grapefruit juice at each meal. This diet plan is meant to help the dieter lose weight quickly and efficiently, but does it work that way? Kelly D. Brownell came up with this fad diet in the 1930’s and he was said to be a renowned expert on obesity and nutrition.  He has published over 13 books, and taken part in over 200 clinical studies relating to weight loss and obesity, which makes him a well rounded scholar in this area. The entire point of this diet is to lose weight at a rapid pace by consuming grapefruit at each meal, but the diet didn’t really catch on until the 1970’s when it was accidentally confused for the Mayo Clinic Grapefruit Diet menu and plan.  The two diets are not correlated.
Grapefruit Diet Claims
The Grapefruit Juice Diet is very much like the Atkins diet, only with added grapefruit at each meal. The claims they make on the website are based entirely around what grapefruit can do for the body, but be mindful, grapefruit can interfere with the absorption of certain medication in some individuals. Because grapefruits are used as blood sugar regulators, they say this diet helps regulate insulin levels and store fat more efficiently. Take a look at a few key claims the website states about the diet and the benefits it promises.
“The best thing about Grapefruit Diet Plan is that it helps one to lose approximately 10 pounds in 12 days and that too without controlling the appetite. The juice of the grapefruit encourages the fat burning process.” 
“Grapefruit forms a core part of the Grapefruit Diet. It is a wonderful fruit that contains simple carbohydrates with high fiber. The fruit has no fat, is low in calories and sodium, and is packed with vitamin C. For those who would like to reduce their weight, it is believed that grapefruit can reduces your appetite and therefore promote weight loss.” 
“With the help of Grapefruit Diet Plan, it is possible to lose up to 10 pounds in 12 days but the best thing about this diet is that it is achieved without any starvation and you will be enjoying normal meals at normal times.”
The interesting thing about this quote is 800 calories really is not a lot of calories each day, so you may be hungry when the day is over.
“During rest your body burns very few calories. So the dinner should be at least two hours before the bedtime.” 
“Citric acid of fresh grapefruit juice has an alkaline reaction that increase the alkalinity in the body. The fruit juice has been found useful in treating many diseases caused by too much acid in the body system.” 
Ingredients In The Grapefruit Diet
The Grapefruit Diet Meal Plan is as follows: They say the dieter should be on the grapefruit diet plan for twelve days, and then take a two day break. Three to four servings of carbohydrates are also allowed in addition to the typical menu. It stays at around 800 calories for one day. A typical day would include some sort of grapefruit for breakfast, whether it be grapefruit juice or the fruit itself, coupled with a protein like eggs or bacon. For lunch it would be similar, because grapefruits whole or juice is required along with meat of some sort and a salad. Dinner would include grapefruit again, meat of some sort, and a vegetable. White onions, potatoes, and celery are not allowed as vegetables. Lastly, for the nighttime snack in case you get hungry, you are allowed to drink a glass of milk or tomato juice. 
The Science (or Lack Thereof) Behind The Grapefruit Diet
There is a lot of science circulating around about the effects of grapefruit and grapefruit juice in the body when it comes to insulin resistance, weight loss, fat burning, and appetite reduction. The company claims ten pounds in 12 days, which does not match up to the study found below, but the patients were also not on 800 calories either. In a study done by NCBI, they took 91 obese patients and gave them either grapefruit juice plain or in capsule form, or apple juice in capsules and then ‘regular’ (known as the placebo group). The study was done for over 12 weeks, and the patients took these capsules or the juice three times a day.
There were no other requirements of diet or caloric intake minus taking the grapefruit or placebo three times per day. What they found was significant changes of weight in the grapefruit versus placebo groups.
“There was also a significant reduction in 2-hour post-glucose insulin level in the grapefruit group compared with placebo. Half of a fresh grapefruit eaten before meals was associated with significant weight loss. In metabolic syndrome patients the effect was also seen with grapefruit products. Insulin resistance was improved with fresh grapefruit.” 
The core part of the Grapefruit Diet is the fact that the grapefruit itself is the key piece as claimed above. The fact that the fruit has no fat or sodium, is high in fiber, and is packed with vitamin C is one of the most important points to note. But does consuming this fruit three times a day really help with appetite reduction? A study done on energy balance (food consumption), water intake, body composition, and the effects grapefruits/ grapefruit juice has on these topics was completed. The main goal was to compare the effects on the body to see if body composition changed, if appetite and food intake were reduced, and how their energy was over the period of the 12 weeks when given the three forms three times per day.
There were 85 participants who were given one of three forms: grapefruit juice, grapefruit, and water over the course of this time.
What they found at the end of it all according to NCBI was,
“The total amount (grams) of food consumed did not change over time. Yet, after preloads were combined with caloric restriction, average dietary energy density and total energy intakes decreased by 20-29% from baseline values. However, differences were not statistically significant among groups.” In regards to energy balance and food intake: “The differences among groups in dietary energy density and total energy intakes were not statistically significant.” 
Another quote that was made regarding rest and the body not burning calories during rest was far fetched and not backed by science. While it is good to still eat a few hours before bed to allow proper digestion, you will still burn calories as you sleep. There are many different studies out there that prove your body burns calories while sleeping, and the more sleep you get, the better off your body composition and resistance to weight gain will be.
According to Psychology Today,
“Most of us assume our bodies burn more calories when we are awake longer, but that's not true. The metabolic rate is down-regulated with less sleep. Translation: When you sleep less, your body starts to burn calories at a slower rate to preserve energy. In the study, people burned on average 400 more calories by sleeping for 3 more hours–that's an additional 2,800 calories burned in just one week.” 
Lastly, the quote regarding alkaline levels in the body is correct, and grapefruit can play a large role in creating alkaline in the body to balance pH levels, which can fight diseases in the body. So how does disease occur in the first place?
According to Raw Food Explained,
“If we consume excessive amounts of acid-forming foods, such as animal and dairy products, the body must tap its alkaline reserves (buffer salts) in order to maintain the proper pH. The kidneys, lungs, and entire physiology is overworked in the process of excreting the neutralized acids from the body.” 
By consuming alkaline rich foods such as grapefruit, you will be naturally helping that balance occur without putting extra stress on the body.
Word On The Street About The Grapefruit Diet
The Grapefruit Diet menu is very strict to say the least, which might make completing the program difficult for some. The dieter will be eating or drinking a lot of grapefruit, so if you are not keen on this fruit, it might be hard to see it through. There were not many actual reviews done on this so called fad diet. There were actually a lot more questions and conversations about it. There were, however, some folks who went through it and saw some results.
Tamika H. (There is no date, or rating for this review.) said,
“The grapefruit diet does work. I’ve done it before and lost about 35 pounds. Only to get comfortable and gain it back. Stay focused eat right and the weight will stay off.” 
Dietician Becky (10/21/12, 1 star) said,
“Many people have done the grapefruit diet—it has been around for years. There is no “truth” to claims that grapefruits help burn body fat, etc. Grapefruits are low calorie and this is the majority of one's food intake—therefore the diet is dangerously low calorie and not providing the nutrients needed.” 
The Bottom Line: Is The Grapefruit Diet Worth A Try?
Depends. When looking into this fad diet, it is likely you will not want to stay on it for longer than a few months at the very maximum. The only cost involved is buying the groceries for the week. This is not a long term diet that will help you to learn better eating habits. You are eating high protein, as well as grapefruits three times per day, which can get old really fast. Sure, you might lose some weight, but that is largely due to the fact that you are only consuming 800 calories per day and it comes in the form of greens and protein. Who wouldn’t lose some weight with that diet? If you like grapefruit, and it wouldn’t interfere with medication you are taking, it is fairly safe for most.
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