Help please! Is drinking grapefruit juice a good way to lose some weight quickly?

Quick is not best. Grapefruit juice and similar pro-metabolic agents can give you an advantage, if you are doing the basics right: high fiber, lower simple carb, high quality protein, medium fat content and moving your body regularly by steadily introducing more physical activity. A body in motion, combined with a slightly net-negative calorie balance is the key to loosing weight and keeping it off.