I bought one of those small round watermelons. Is eating half of it too much? I guess I'm trying to figure out what reasonable is, since me and reasonable don't usually reside in the same sentence with eating.

ETA: If it helps it's a 7" diameter melon?

It depends on what your plan is. If you're doing low-carb, stay away from it because watermelon has an awful lot of sugar for a fruit. If you're watching calories or just doing some other kind of portion control, though, it's a pretty good option - only around 50 calories per cup. If it's only 7" in diameter, there are probably around 250-300 calories per half, which I would consider pretty reasonable depending on what else you've had to eat today.

Personally, I looove watermelon, so I buy one just about every week. I spend ten minutes chopping it up and then just keep it in a tupperware thingy in the fridge, so I can have a bowl of ice-cold watermelon chunks for dessert every night.

Actually watermelon is on the low spectrum of sugary fruit.
http://www.fitsugar.com/Sugar-Content-Fruit-20134844

Eat as much as you like until you get full. If you eat a little too much past fullness you'll be rushing to the bathroom all night. I found that out the hard way

According to the USDA's food website, 1 cup of watermelon has 9.42 grams of sugar. I would say that's pretty low.

Watermelon is roughly 10 calories per ounce. To me, 10 ounces isn't much in a bowl, and it's 100 calories worth. Watermelon, as heavy as it is, can quickly ring up the calories, and they aren't free. I weigh it like everything else.

There's a reason it's called "water"melon...lol