Scientists have known for some time that excess body fat isn’t good for you. Obesity—which means “overfat"— is considered as deadly as smoking, according to some analyses. For years, obesity was determined by an individual’s weight, or by her Body Mass Index (BMI), which roughly calculates your body size while trying to account for bone mass.

One of the problems with the Body Mass Index is that it doesn’t account for your muscle mass. As a result, some athletes who have a much lower percentage of body fat and higher percentage of muscle-can compute to be “overweight” or, in some rare cases, “overfat.”

More recently, studies have begun to show that while being overfat in general isn’t good, carrying excess body fat specifically around your belly, is really really bad. Studies show that women who have a waistline measuring 35 inches or more are at greater risk for heart disease and diabetes than those whose waistline measurements are smaller. For men, a waistline measurement of 40 inches or above can be an indicator of the same health risks. Heart disease is the number one killer of American women, and rates of diabetes have reached epidemic levels. The connection between the measurement of your waist and your risk of dying from one of these diseases is no mere coincidence. Belly fat may actually cause these diseases.

“Belly Fat” is actually two different types of fat: subcutaneous and visceral. Subcutaneous fat can be described as the fat that you can see. Subcutaneous means “beneath” (sub) “the skin” (cutaneous), and it’s no big secret that this fat resides all over. In some spots, your thighs, underarms, belly, it may be thicker than in others, but for the most part it’s everywhere. A moderate amount of subcutaneous fat is essential for life—for one thing, it keeps you from freezing to death in the winter. But too much of it can be bad for you, starting with the fact that subcutaneous fat functions as a visible sign of being overweight or obese.  

The second type of fat is visceral fat. Visceral fat is much more dangerous and difficult to lose. Visceral fat resides deep within your torso and is sometimes referred to as “hidden” belly fat. It could be called “deadly” fat. Because of its proximity to your heart and liver, excess visceral fat can increase your risk of all sorts of diseases, from heart disease and diabetes to cancer and Alzheimer’s disease. You can cut calories and exercise religiously and still be left with too much visceral fat.

The only way to minimize both visceral and subcutaneous fat simultaneously is to eat the right…fat.

The Flat Belly Diet is made up of two parts: a Four-Day Anti-Bloat Jumpstart and the Basic Eating Plan. Even though you may be tempted to follow one part without the other, you should start with the Anti-Bloat Jumpstart, then move straight into the four-week eating plan.

The first phase of the diet—the Jumpstart—is designed to erase belly bloat. This part of the diet is somewhat regimented, since each food is carefully selected to reduce bloat and soothe your digestive tract. For best results, you'll need to follow the meal plans exactly. You'll be eating four smaller meals each day which will reduce the amount of food in your digestive system at any one time, cut back on the release of stomach acids, and get your body used to a four-meal-a day schedule which you'll follow for the rest of the Flat Belly Diet.

After you complete the jumpstart you'll begin the Flat Belly program. You will learn very quickly that the Flat Belly Diet is different from other diet plans. You'll eat very well on the Flat Belly Diet as you'll see when you review your meal plans. There are options for quick, no cook meals, as well as recipes that you can prepare and serve for your whole family on those nights when you have time to cook.

There is lots of additional information about the diet in this tutorial, as well as in the Learn section on the site. 

How should I use the book and the online service together?

Based on the breakthrough Flat Belly Diet! book, the online service includes all of the health and science aspects found in the book, but it goes even further by customizing a plan that's perfect for you.

The book introduces you to the program and serves as a handy reference guide, while the online program offers planning and tracking tools to put the program into action. With the online program you get a fully customized plan based on your food preferences, dietary restrictions, and daily calorie needs. The book offers a general 1,600 calorie-per-day plan whereas the site prescribes a daily meal plan within a targeted calorie range based on your age, gender, height, weight, and current activity level. This is a personalized experience that the book simply can't provide.

Another powerful site benefit is its community. Connecting with other members on the message boards and buddy lists creates a support network that dramatically increases your chance for success. The message boards also have special "Ask the Coaches" forums where you can get hands-on nutrition, motivation, and fitness guidance-sort of a way to ask the book questions.