Everyone knows that being overweight can lead to high blood pressure, but do you know why? Your omentum is almost like an organ that stores fat. It lives under your stomach, and it is a space hog. When it gets bigger, it elbows your other organs out of the way. One of those organs is your kidneys, and they control your blood pressure. When they get squashed, they feel like they aren't getting enough blood, so they raise your blood pressure until they are happier. (Which makes your arteries unhappy, but that's another story.) Luckily, your omentum is the easiest weight to lose, because it is the first place your body goes to when it needs more energy than it has on hand. So if you lose the weight off your belly, chances are you will lower that pesky blood pressure.

Everyone knows there is good cholesterol and bad cholesterol, but do you know why? Your arteries have a slick layer on the inside so that your blood can run around easily. Various things (high blood pressure, too much sugar in your blood) can make little tears in that layer. That's bad, and there is a little (metaphorical) guy who runs around in your arteries and patches up the tears. He uses cholesterol to do it. Now, good cholesterol is tough, and slick, a lot like the layer it is patching, and leaves your arteries practically as good as new. Then there is bad cholesterol. Bad cholesterol isn't as strong, so it takes a lot more of it to make a patch, and it's a bit sticky, so other things in your blood, especially other bad cholesterol, can get stuck to it. That's when it clogs up your arteries. The good news is that the little guy won't use bad cholesterol until he runs out of good cholesterol, so if your good cholesterol is high enough, having a little bad cholesterol won't hurt you.

And not just at midnight. If you don't eat for two hours before you sleep, you're actually losing weight at the end of the night. If you eat and then go right to sleep, your body will store all those calories. Around your waist. As far as sleep goes, try to get a full night's worth. If you don't, your body will try to replace sleep with food, and you will be hungry all day long.

Everyone knows that sugar is bad for you, but do you know why? There are two reasons. One, excess sugar in your blood makes little cuts in the lining of your arteries. Think of it as sharp little crystals scraping their way along and leaving a path of destruction behind them. Two, sugar leads to more sugar. When you eat sugar, you get an energy boost that lasts a couple of hours. Trouble is, when that energy wears off, what your body craves is more sugar. It's that roller coaster that gets you. Not the first bite of brownie, but the fourth and fifth and sixth. You can knock that roller coaster down to size by having a handful of nuts or a slice of whole-grain bread before you eat the brownie. It doesn't make it easy to stay away from the dessert bar, but it might make it possible.

A lot of diet books tell you to drink water when you feel hungry, but do you know why? It isn't to make you feel full, because it won't. Your body knows the difference between water and food. Actually, the part of your brain that tells you you're hungry is right next to the part that tells you you're thirsty. Sometimes the signals can get mixed up. So have that glass of water before you dive into a chocolate bar. It may just satisfy a craving you didn't know you had.

For more information about your insides and how they work, read "YOU: on a Diet" by Michael Roizen, MD and Mehmet Oz, MD.