The grapefruit diet has been around since the days when Jayne Mansfield and Marilyn Monroe graced the silver screen. In fact, you may know it as the "Hollywood diet" due to the glamour-puss following the diet has attracted. Advocates rave that its daily intake of grapefruit and grapefruit juice, as part of a regimen that, at its most restrictive, limits you to 800 calories daily (and only a few choice foods, such as hard-boiled eggs and toast) is a quick way to shed pounds. But doctors contend that these restrictions and other aspects of the diet can also have a lot of unintended and unwanted side effects.
Much has been made of grapefruit's interaction with existing drugs you may be taking, including contraceptives. This healthy fruit can have unhealthy side effects, especially in large quantities (as these diets call for). For starters, it can reduce the effectiveness of some drugs, or exacerbate the side effects of others. This diet has been known to contribute to serious medical problems, such as blood clots, which are due to how the fruit affects the way certain pills are processed. Check with your doctor or the drug interaction database to find out possible interactions with your medications.
The light-headedness and general feeling of being unwell that you may experience on this diet is due to the caloric intake being so low. When the body doesn't get the nutrients it needs, it's manifested in side effects like fatigue and dizziness.
Large amounts of citrus, consumed in some cases at every meal, can irritate the stomach lining. That can cause problems such as acid reflux and nausea.
Teeth-related problems are a major concern with the grapefruit diet, because this fruit is so acidic. The acid in it can wear away at the enamel that protects your teeth, leading to decay.
This diet is so unrealistic that it's not something you can sustain in the way you can with a diet rich in a variety of healthy foods. What that means is when you begin to add more foods to your diet again, your metabolism is shot and you can quickly regain all the weight you lost--and then some.