Grapefruit is not recommended. Other than 11g carbs in a HALF GRAPEFRUIT (!!!!!!), you won’t get much else from it. It contains less than a gram of protien (.09g) and even less fat (.02g). 
 
If you are ever in doubt, do a quick google search of the item you want to eat, followed by “nutrition information.” Remember that you will have about 20 carbs for your day when you are deciding if you want to eat that item!