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 so 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 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.

Cut calories from anywhere in your diet and you will lose pounds. Add in cardiovascular exercise and strength training, and you will even lose body fat. But this diet specifically targets belly fat—unlike any other diet. That’s because the Flat Belly Diet contains a significant amount of monounsaturated fats, or MUFAs. These unique fats—brought to our attention by researchers studying the health benefits of the Mediterranean diet and lifestyle—are like little miracle workers in your belly.

Studies show that moderate-fat diets—containing up to 40% fat—are more effective at helping people lose weight and keep it off for life than low-fat diets containing less than 30% fat. The additional fat makes food taste better and boosts satisfaction—key factors wherever food is involved! When you consume a reduced-calorie diet that’s high in the specific type of healthy fat—the MUFA—you not only lose pounds and feel satisfied, but you will also lose visceral belly fat.

What we’ve done here is taken the basic scientifically proven principles of a healthy Mediterranean diet and enhanced them by ensuring that you get a specific amount of MUFA in a specific quantity at each meal.