Ok, I don't know you, and I LOVE fruit as much as anyone (it's actually a joke with my friends), but you cannot live off of nothing but strawberries and raspberries!!! Even crazy hermits like John the Baptist ate some protein (wild locusts) and even carbs and fat (honey, hello!!).
If you've been eating that little, you probably have put your body into starvation mode. Eat small, frequent, BALANCED meals. Try to eat approximately equal amounts of protein,(good) carbs, and (good) fat in each meal. Eat every couple of hours (as soon as you feel hungry) and then stop eating when you no longer feel hungry (don't keep eating until you feel FULL).
If you eat too little, your body goes into starvation mode and tries to conserve fat no matter what. Then, when you start to eat again, your body will try to put on more weight than you lost in order to prepare for the next famine. Then you've raised your setpoint (the weight your body naturally tries to maintain). Lowering your setpoint is hard, but I believe some keys to that are increasing exercise (and including some strength training) and eating frequently. And making sure you get ENOUGH nutrition.
Instead of trying to severely decrease your caloric intake, increase your output by exercising!
Sorry if I'm ranting, but when you said you were eating 1600 calories of FRUIT and nothing else, I got a little concerned about you.
Take care of your body, please! You can't trade it in for a new one if it breaks.