Article From http://www.watermelonrind.com/why-eat-watermelon-rind.html
I personally remember my parents, as well as the parents of other friends and relatives, always stepping in when they seen us chewing away on the watermelon rind, saying don't eat that, get another fresh piece of watermelon instead. Their reasoning was always the same, that eating watermelon rind will give you an upset stomach. It must have started out as an old wives' tale way back when, as almost all parents I can remember seemed to have the same position on it. The fact is that it will not hurt your stomach, not any more than eating too many green apples would, or eating too many fresh cherries. The key with all vegetables and fruits, is to eat them in moderation, and also to make sure you have a healthy diversity in the fruits and veggies you choose to eat.
If you don't like to eat the watermelon rind simply because it doesn't taste as good as the pink flesh, then juice it and add a little sugar. Or you can even blend it up with other fruits in a watermelon rind smoothie. If you add other sweeter fruits to help balance out the flavor, you can really consume a ton of nutrients in doing so. If those two options aren't enough, then choose from one of many of our other watermelon rind recipes. Our website it the largest watermelon rind based recipe collection in the English speaking world. We have recipes for watermelon rind jams, jellies, salads, candy, Asian watermelon rind chow chow, and even Indian watermelon rind chutney. Many of these recipes are extremely easy to make, and after doing so you will be happy that you finally decided to stop wasting all of that watermelon rind.
With regard to the nutrition of watermelon rind, there are many benefits to eating it. It contains large amounts of citrulline, an amino acid that has many health benefits. Watermelon rind is also rich in vitamin C, beta carotene, and lycopene. The rind also contains smaller amounts of vitamin A, Thiamine, Riboflavin, Niacin, Vitamin B6, Calcium, Iron, Magnesium, Phosphorus, Potassium, and even Zinc. It is also known that the more yellow the inside of the watermelon flesh and rind are, the more nutritious it is. So if you can, go out of your way to buy yellow flesh watermelon, as you will be getting the most nutrients and vitamins for your money's worth. We hope that our website will help dispel some of the false rumors about watermelon rind, and that more people will enjoy all of the benefits gained by eating it.