One of the most discouraging things about trying to lose weight is hitting the plateau. Typically, you start out on a diet filled with determination. Your efforts payoff almost immediately as you rapidly drop a few pounds. And then, a few weeks to a month into your diet, the weight loss slows or even grinds to a halt.

You have probably heard many explanations for this phenomenon: "The initial weight loss was just water." "The last pounds on are the first pounds off." "You now weigh as much as nature intended." And more.

The set point

Some theorists say every individual has a personal metabolic rate that maintains a given weight, regardless of caloric intake. That personal "ideal" weight, called the set point, is thought to be predetermined by the hypothalamus, an area deep in the brain.

Although the set point theory is based on scientific fact, the mechanism involved is still not fully understood. It has also been oversimplified and often distorted by people promoting a particular diet.

If the set point were really as simple as it sounds, gaining weight would be as difficult as losing it. And we all know that isn't true.

At the heart of the set point theory and of the plateau phenomenon is your body's response to calorie restriction. It may be the new millennium, but the human body responds to outside stimuli the same way it did when we were hunting the woolly mammoth. In the face of danger, it secretes extra adrenaline to trigger the "fight or flight" instinct. And in the face of food shortages, it slows down" metabolism to protect against starvation during the coming "famine.

You've lost those first few pounds because you're eating less than you need and your body has drawn on your emergency fat stores to up the difference. It "knows" that once all the glycogen and fat are gone, it will have to start on your muscles, and that would be a disaster. (Muscle wasting is seen in victims of starvation.) You may be far from depleting all of your fat, but your body has no way of how long this "famine" will last, so it plans ahead. It makes your body a knowing efficient energy consumer to preserve the fat you have on deposit. Thanks a lot! if you reduce your calorie intake even further, you may lose a bit more weight, but it will be hard going and gradually your body will adjust to the new calorie ration and slow down even more. This is a real low point in any weight-loss diet, and it's the people give up.

You have no energy, you're hungry; you feel deprived, and you don't seem to be losing any weight. A hot fudge sundae starts looking awfully attractive right about now. Luckily, there's a simple way to "fool" your body and jump off that plateau. You already know what it is, don't you?

Boost your activity level, and you will boost your metabolism.

Add a few minutes to your daily workout, up the intensity, and before you know it, you'll be losing pounds again. As I've already said, you get a double bonus when you do this, since the extra activity will burn calories at the same time it revs up your metabolism.