I love grapefruit and have eaten it on and off for several years depending on seasons. Recently I have come across several different claims that grapefruit help you burn fat and things like "If you eat one grapefruit per day for a whole month you will lose 3kg."

What are the pros and cons of eating 1-3 grapefruits every day, and where is the resource to your claim?

  • It is unclear that whether you want to know the benefits of eating grapefruit or you just want to check for any proof for the above claim. Maybe skeptics.SE is a better choice. Sep 20 '11 at 4:10
  • 1
    Con: they taste awful.
    – xpda
    Sep 20 '11 at 5:04
  • @xpda You eat the skin together? Sep 20 '11 at 8:49
  • @gunbuster363 Well, I wanted to know the pros and cons of eating lots of grapefruit and the proof behind the statements. Thought I was very clear, sorry!
    – Zolomon
    Sep 20 '11 at 9:36

"If you eat one grapefruit per day for a whole month you will lose 3kg."

Not exactly. However, below are 2 studies looking at grapefruit consumed prior to meals. They look at weight loss, as well as health factors like cholesterol and insulin resistance. (Note: these are not what is typically thought of as the "grapefruit diet".)

  • A 12 week study from Vanderbilt compares weight loss in obese subjects consuming either grapefruit (GF), grapefruit juice (GFJ), or water 20 minutes prior to their reduced calorie meals. Also, the subjects were instructed to wear pedometers.

The study found that it didn't matter whether the grapefruit was in the form of fruit or juice, (even water achieved the same weight loss) as long as they were "pre-loaded" meaning consumed before the meal. With the preloading:

The rate of weight loss increased significantly by 13.3% (p < .0001) during the caloric restriction + preload phase for an additional loss of 5.8 ±± 3.9, 5.9 ±± 3.6 and 6.7 ±± 3.1 kg (GF, GFJ and water, respectively).

Subjects experienced 7.1% weight loss overall, with significant decreases in percentage body, trunk, android and gynoid fat, as well as waist circumferences (-4.5 cm).

The one health benefit that the GF and GFJ did show over the water preload was the improvement in HDL.

It is striking that HDL-C levels increased up to 8.2% from baseline in GF and GFJ groups, a significant change compared to decreased HDL-C in the water preload group.

There was a mean increase in HDL-C from baseline by 6.2% in the GF group and 8.2% in the GFJ group - which differed significantly from the mean decrease of 3.7% in the water group (p = 0.003 and 0.009, respectively).

So with this study, it was the preloading, whether with water, juice or fruit, that increased the weight loss of people on a calorie reduced diet (who were also wearing a pedometer).

However, if you are interested in improving your HDL levels, adding grapefruit or grapefruit juice prior to meals will help according to this study.

  • Another study looking at the effects of grapefruit on weight and insulin resistance: relationship to the metabolic syndrome concluded:

After 12 weeks, the fresh grapefruit group had lost 1.6 kg, the grapefruit juice group had lost 1.5 kg, the grapefruit capsule group had lost 1.1 kg, and the placebo group had lost 0.3 kg. The fresh grapefruit group lost significantly more weight than the placebo group (P < .05).

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. Although the mechanism of this weight loss is unknown it would appear reasonable to include grapefruit in a weight reduction diet.

I only have access to the abstract which does not compare half of a fresh grapefruit with any other fruit.

Cons: Grapefruit does have the potential to interact with drugs. WebMD cautions pregnant women, postmenopausal women, or women with breast cancer about drinking excessive amounts of grapefruit juice or taking grapefruit supplements. I don't know of any studies with eating more than one and a half grapefruits per day.

  • Grapefruit juice is highly acidic, so another con is to take that into account. If you don't mitigate the acid, frequent use can cause advanced wear and tear on your teeth.
    – Zolomon
    Nov 28 '12 at 14:24

You can refer this WHFoods page about grapefruit, it is very detailed about the benefit of eating grapefruit. Check about the result of overdose nutrients here. And please don't consume drug with grapefruit, it is very dangerous, please refer to the page about grapefruit.

By the way, World Healthiest Foods is a very good site about healthy food.

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