The Promise

The grapefruit diet has outlasted most fad diets. People were even trying it back in the 1930s.

Its fans claim that grapefruit contains certain enzymes that, when eaten before other foods, help burn off fat.

The diet, which has several variations, lasts 10-12 days and claims to help you lose as much as 10 pounds.

Before you head for the citrus aisle, you need to get the facts, especially about the diets fat-burning claim.

What You Can Eat and What You Can't

You'd better like grapefruit -- a lot. Most versions of this diet recommend eating it with every meal.

The classic version of the diet involves:

Cutting back on sugar and carbs (including rice, potatoes, and pasta)

Avoiding certain foods, such as celery and white onion

Eating more of foods that are high in protein, fat, and/or cholesterol (such as eggs, pork, and red meat)

Eating grapefruit or drinking grapefruit juice before or with every meal

Most variations also cut calories, some to as low as 800 calories per day.

On the diet, you also drink 8 glasses of water and 1 cup of coffee daily.

Level of Effort: Medium

Some versions of the grapefruit diet are really strict. Others are fairly flexible. Either way, you'll need to have a taste for the tart fruit.

Limitations: These depend on what version of the grapefruit diet you do.

Some versions curb carbs and bulk up on high-fat, high-cholesterol foods or cut calories drastically. Others just ask you to eat grapefruit at or before every meal, and you can pretty much eat whatever you want otherwise. The classic version involves combining foods (to get the alleged fat-burning effect), such as bacon and salad.

Cooking and shopping: You'll be putting a lot of grapefruit in your shopping cart, but there's not a lot of extra prep work.

Packaged foods and meals? No.

In-person meetings? No.

Exercise: Not required.

Does It Allow for Dietary Restrictions or Preferences?

Vegetarians and vegans: The original version of the diet includes meat. Vegetarians and vegans would need to tweak the diet to make it work for them.

Gluten-free: Some versions of the diet cut back on carbs, including carbs that contain gluten. But the diet doesn't ban gluten. You'll need to check food labels if you're trying to avoid gluten completely.

What Else You Should Know

Cost: Grapefruit doesn't cost a lot, depending on the season and where you live.

Support: This is a diet you do on your own.

Does It Work?

Sorry, but grapefruit doesn't burn fat.

There have been a few studies about grapefruit and weight loss. In one, obese people who ate half a grapefruit before meals for 12 weeks lost more weight than those who didn't eat or drink any grapefruit products.

It may be that the water in grapefruit helps you feel full, and then you eat less. But if you're hoping that grapefruit will melt fat, you're going to be disappointed.

Trying to lose 10 pounds in 10 days isn't healthy, nor is it recommended by experts. Even if it worked, you'd be likely to gain it all back, as with any fad diet. For lasting results, it's much better to lose weight at a slower, steadier rate. Focus on a plan you can live with for life.

Is It Good for Certain Conditions?

No, this is not a recommended plan for any conditions. While you may lose weight, it's unlikely you'd keep it off, because this diet isn't doable long-term.

Grapefruit can interfere with certain prescription drugs, including statins (cholesterol drugs) and some blood pressure drugs. It increases the effect of these drugs and can cause adverse effects hours before and hours after taking these medications.

If you have a health condition, ask your doctor about whether you should avoid eating grapefruit or drinking its juice.

The Final Word

Dont bother with this diet. Such a limited variety of foods in small portions is the prescription for boredom. It's exactly the formula to cause most dieters to give up trying to lose weight.

Grapefruit can be part of a healthy weight loss diet because it's nutritious, not because of any mysterious fat-burning properties. If you're a grapefruit lover, reap the benefits of this super-nutritious fruit by enjoying a serving before meals. A half grapefruit or a glass of grapefruit juice before meals may help fill you up, so you'll eat fewer calories at meals and potentially lose weight.