Is it ok to exercise with an empty stomach?

Yes: Should be fine as long as you dont feel weak or dizzy.

Yes: There's no medical contraindication to exercising on an empty stomach unless it makes you uncomfortable. A protein shake after exercise is often recommended to nourish the muscles and help with burning fat.

Should be OK.: In fact, I generally recommend that people exercise first thing in the morning, before eating breakfast or even having coffee, to maximize the weight loss benefit of exercise. Start slow to assess your tolerance of it though. If you don't handle it well, then exercise later in the day a couple of hours after a light, carbohydrate-predominant meal.