Here's scientific evidence that one weird diet might actually work. Louisiana State University researchers recently discovered that people who ate half a grapefruit three times a day lost 4 pounds in 12 weeks,  even though they hadn't deliberately altered any other part of their diets. They also lowered their blood pressure by 6 points, enough to reduce their risk of stroke by 40 percent. Although the mechanism isn't clear, researchers speculate that grapefruit's acidity may slow your rate of digestion, helping keep you full longer. The scientists note that for weight loss, substituting 8 ounces of juice for each serving of the fruit is just as effective. Try Tropicana Pure Premium Ruby Red Grapefruit Juice: A new study determined that it contains more heart-healthy antioxidants than any other brand tested.