Yes, carbs break down into glucose, fructose or fiber. Starch is just a chain of glucose molecules. Other than it takes a little longer to absorb, starch is the same as glucose as far as your body is concerned. Sugar (sucrose) is a glucose and a fructose stuck together in equal amounts.
Originally Posted by Bamaphotopro
Fructose can only be processed by your liver. I heard a suggestion to keep fructose to less than 15 grams a day. Watermelon is nearly pure fructose. So 57g of fructose from the watermelon can be a big load for your liver.
Carbs aren't bad. For example, they help you preferentially absorb tryptophan, and they make up the bulk of the glycogen stored in your liver. You need them if you're doing high intensity exercises. If you're a normal person, you don't need more than 100-150g per day. Some athletes can eat more than that and be okay.
The main thing is: eat around 100-150g of carbohydrates a day to maintain your weight, and 50-100g per day to lose weight. If you're an endurance athlete, you'll probably need to bump that up a bit. Make sure they come from vegetables and fruits. 2-3 pieces of fruit a day is okay. Having a whole watermelon every day isn't such a great idea. It's really not worth stressing about too much. Just aim for berries instead of bananas and eat vegetables and sweet potatoes and regular potatoes if you want or need the starch.
Poke it quickly, with a stick.