A: Sugar and salt both stimulate your appetite. Thanks to a phenomenon known as sensory specific satiety, though, you can fill up on something sweet and only feel full of sweet food. If you switch over to salty, you are, in essence, activating a separate appetite meter that starts at empty. This is why we have room for dessert at the end of a big meal.
You break the cycle by taming the extremes. Our sensitivity to sugar and salt is dulled because of the huge amounts of both in manufactured foods. Try starting your day with a breakfast of unsweetened whole grain cereals, nonfat dairy, and fruit, and follow it with a midmorning snack that is mildly sweet, such as dried fruit. Have a salty snack—nuts, say—in the afternoon, but don't mix it with any sweet flavors. After dinner take a break before you decide if you want a sweet dessert or a salty snack. You'll find this pattern quickly becomes habit and provides the structure you need to prevent the alternating cravings from getting started.
Here's one more crucial tip: Read food labels. Many pasta sauces and salad dressings have as much sugar as chocolate ice cream topping! Some breakfast cereals have more salt than corn chips. If a food is supposed to be salty, it should not have sugar (under any of its many aliases, such as high-fructose corn syrup) near the top of the ingredient list. If a food is supposed to be sweet, then make sure sodium isn't a major ingredient. Choose foods wisely, and you'll feel satisfied on fewer calories.