Biochemistry of Love

Going on a strict diet is like holding your breath underwater. Try to stay under and eventually you automatically inhale -- and then you drown. Try to stay on a strict diet and eventually you come up gasping for carbohydrates -- and then you're off the diet and on a binge. The reason is that both acts force you to fight against something your brain is commanding you to do. You're drowning -- breathe! You're starving -- eat! You can't win that fight. Your brain will always beat you. What you can do is manipulate your brain so that it becomes your ally.

When most of us think about being hungry, we think about our stomach. It's growling, after all. But where do you actually register hunger? In your head. The link between the two is called the hypothalamus, a small extension of the brain just above the brain stem ("o" in the illustration). That's where the mind-body connection occurs.

Every thirty minutes or so, your stomach sends a burst of a chemical called ghrelin into your bloodstream. When the ghrelin reaches the hypothalamus, another chemical, NPY, shows up and tells your brain that you're hungry. But of course you don't feel hungry every thirty minutes. That's because NPY is in constant competition with another chemical, called CART. CART makes you feel full. (The c stands for cocaine and the a for amphetamine, and CART is not unrelated to drug-induced munchies. See "Forget About Your Stomach".) Just as ghrelin triggers NPY (hungry!), a chemical called leptin triggers CART (stuffed). It's a self-regulating system. But modern life, with its convenience food and constant stress, throws the system out of whack. How to fix it:

1. One of the most effective things you can do is also one of the simplest. Eat a handful of walnuts, hazelnuts, or almonds about thirty minutes before a meal. The good fats that nuts contain cause your stomach to suppress ghrelin production, but it takes about half an hour for them to kick in. Note: Peanuts aren't actually nuts, and they contain a lot of saturated ("bad") fats. Stick with something that grows on a tree.

2. The only way any of this is going to work is if you give yourself a break. Ever drive a car with a talking GPS? When the lady tells you to turn left in four hundred feet, then stay straight for 2.2 miles, if you mess up, notice that she doesn't tell you to drive off a cliff. She tells you to turn around the next chance you get. (She says U-turn, we say You-turn.) Point is: If you accidentally inhale a crème brûlée, relax. You're dieting without freaking out, and that's good. Here's a fact that may inspire: The obesity epidemic comes down to one hundred calories a day. That's it. If you try to cut out more than that, your metabolism slows down anyway. Thirty-five hundred calories is one pound, so in thirty-five days you lose a pound, every year you lose ten, twenty every two years. There goes your epidemic. Just when you take a wrong turn and hit a hunk of cake, turn around the next chance you get.

3. The hypothalamus contains a sort of hunger regulator called the satiety center. That's where ghrelin and leptin have their ongoing smackdown. The satiety center registers desire not only for food but for the other three major behavioral drivers: thirst, sleep, and sex. Often, what we register as hunger is actually a desire for one of these. So if you're hungry at work, try water first. If you're hungry at home, screw. (We have a friend who lost weight just by having more sex.) Explain that it's for your health.

1. One of the most effective things you can do is also one of the simplest. Eat a handful of walnuts, hazelnuts, or almonds about thirty minutes before a meal. The good fats that nuts contain cause your stomach to suppress ghrelin production, but it takes about half an hour for them to kick in. Note: Peanuts aren't actually nuts, and they contain a lot of saturated ("bad") fats. Stick with something that grows on a tree.