Tangy and sweet, grapefruit has long been a popular citrus choice among dieters. It is thought to promote weight loss, and grapefruit can break down fats, due to a fat-burning flavonoid present in the fruit. But the amount of grapefruit--and calories--you would need to consume in order to benefit from the flavonoid may more than offset the weight-loss benefits you would obtain from eating grapefruit.
Grapefruit Study
Murray Huff, a researcher at the the University of Ontario, discovered the grapefruit flavonoid, according to an article in the 2009 edition of "Diabetes." Huff wanted to test the longstanding but unproven theory that grapefruit aided weight loss. In Huff's study, he fed mice sugar and lard to fatten them up and a grapefruit flavonoid to slim them down. The mice lost weight without altering their diets. A grapefruit flavonoid, Huff said in his report, breaks down and burns off fat.
Weight Loss
Before you rush to the store to stock up on grapefruit and grapefruit juice, consider Huff's sober conclusions: It will prove harder for you than mice to lose weight by consuming grapefruit. To obtain as much fat-burning benefit as the mice, you would need to drink 6 to 8 cups of grapefruit juice a day. This may not seem like a particular hardship until you add up the calories in 8 cups of grapefruit juice.
Calories and Weight Gain
One cup of grapefruit juice contains 90 calories, and 8 cups -- the maximum Huff recommends -- contains 720 calories. If you added 720 calories to your daily diet, you could gain 1 lb. every four to five days. You could not lose weight drinking grapefruit unless -- and no evidence suggests this -- the flavonoid in grapefruit burned more than 720 calories a day.
Toxic Drug Interactions
Grapefruit can turn toxic when combined with many medications. Side effects can prove serous, and sometimes fatal. When you ingest grapefruit, an enzyme called CYP34A shuts down and your body stops metabolizing some drugs. This can lead to a lethal dose of the medication in your system. Some drugs that react extremely negatively with grapefruit include birth control pills, statins, heart medications and sedatives. If you take any medications, ask a doctor if you can safely include grapefruit in your diet.
References
- "The Toronto Star"; Grapefruit Glory: Joseph Hall; July 2009
- U.S. Department of Agriculture: My Pyramid
- U.S. Department of Agriculture: Nutrient Database
- "St. Petersburg Times"; State Study to Explore Grapefruit as Diet Aid; Julie Hauserman; March 2003
- "The Sun"; Killer Grapefruit Alert to Slimmers; Emma Morton; April 2009
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