The F-Plan Diet launched in 1983, with fiber as the key focus for weight loss. The author of the F-Plan Diet, Audrey Eyton, called for you to consume between 40 and 50 grams of roughage daily, exceeding the Institute of Medicine's recommendation of 38 grams for men and 25 grams for women. The F2 Diet is the updated version of this original plan; this plan, which claims faster results, was first published in book form in 2006. A typical breakfast includes half of a grapefruit, which has hunger-curbing and insulin-stabilizing properties. If grapefruit isn't an option for you, the diet can still be followed with success.
In a sample plan on the F2 Diet, you'll usually begin the day with half a grapefruit, a bowl of high-fiber cereal, skim milk, a lightly ripe banana and a probiotic drink. The grapefruit and cereal are pretty much prescribed every day. At lunch, you enjoy a specially made F2 soup with whole-wheat toast, hummus and tomatoes; dessert is an apple. At dinner, you'll eat whole-grain pasta, marinara sauce, a green salad and even ice cream with berries. The grapefruit really is a small portion of the total day's meal plan, though it is a standard -- along with the special soup or a salad, high-fiber bread and a probiotic-containing food -- to be eaten daily.
Citrus fruit of just about any kind can be substituted for the grapefruit. Although oranges have slightly more natural sugars, they have far more fiber -- 4.4 grams in one large orange vs. 0.9 gram in half of large grapefruit. Tangerines and tangelos are other choices with sweeter flavors and notable fiber content. Pomelos, which taste much like grapefruit with a slightly sweeter, more mellow bite, are another option. Ugli fruit, a citrus fruit that comes from Jamaica, are almost as large as grapefruit but have a sweeter, more tangerinelike flavor and could be a sub.
A 1/2-cup serving of raspberries or blackberries offers almost four times the fiber of one-half of a grapefruit and has none of the bitter aftertaste that might cause you to shy away from the citrus option. Choosing raspberries or blackberries also keeps your carbohydrate and sugar grams in check. In addition, a cup of strawberries provides more fiber and ample vitamin C, one of the primary vitamins offered by the grapefruit.
If you're looking for an alternative to grapefruit because you're on medication that precludes consumption of the fruit, avoid pomelos, tangelos and ugli fruit as substitutes. All of these have been bred with grapefruit and can contain the same compounds that cause medications, such as some statin drugs and blood-pressure-lowering drugs, to resist breakdown in the body. As a result, the drugs may stay in your system for too long and potentially increase your risk of developing liver damage and kidney failure. Instead of grapefruit, you might opt for an orange or a high-fiber fruit that's not citrus.