When on the grapefruit program one diet tip to take advantage of is the unlimited amount of black coffee and water you are allowed to drink.
This is a great diet tip because when you consume a lot of hot liquids most individuals will find that it blunts the feelings of hunger they experience.
Since you are only allowed to be eating three meals a day plus one snack before bed, it is quite likely that there will be some hunger present. Coupled with the fact that you aren't taking in many starchy carbohydrates, which usually cause people to feel full, and it wouldn't be surprising that you'll welcome anything to tide you over.
Just remember with this diet tip that the coffee you drink must be black and cannot under any circumstance have added sugars to it. You could use artificial sweetener however so for those who dislike straight coffee that is always an option. Furthermore, you might want to look into some of the popular sugar-free syrups out there as they come in a range of flavours like vanilla, hazelnut and butterscotch. Adding these to your coffee might just be what you need to give your tastebuds a little something extra too, making it easier to stick with the plan.
If you are going to consume regular coffee and are finding you are drinking quite a bit, consider increasing your water intake slightly as well to help offset the dehydration effects that will be seen.