Are salads, vegetables and fruit all you're eating? What about lean protein, dairy, healthy fats? You aren't getting nearly enough nutrients that your body needs. You could actually use some protein and healthy fats more than you need the fruit, which has a lot of sugar in it, even if is natural. Yogurt is chock full of, both protein and healthy fats, as are eggs, lean meats, fish, avocados, peanut butter, etc.
If you've lost 5 lbs in a week, that's too much...