The word is getting out that most Americans are overweight (sometimes referred to as obesity), but a lot of people are still not aware that includes them.

We're not just talking about not looking good in a bathing suit. Even someone who is just "a little round," or "pleasantly plump" is already at higher risk for significant health problems that are costing Americans $130 billion a year. Fully two out of three Americans are overweight today.

So just how fat is too fat? The euphemisms we use nowadays to refer to body weight mostly imply that it's a matter of image or appearance, distracting from the real issue-excess weight is hurting our health. So how do you know when to be concerned? When has body weight gone from a cosmetic issue to one of well-being?

The standard tool for measuring that is the Body Mass Index (BMI). The BMI calculates height and weight to come up with a score that is indicative of a class of health risk. A score of 18.5 to 25 is typically considered a healthy BMI. Above 25, the level of body fat begins to constitute a health risk, because the excess contributes to problems like elevated blood pressure, elevated blood sugars and high cholesterol, which all lead to serious ailments.

A woman who is 5-foot-4 and 155 pounds has a BMI of 27. That's overweight, and she's already at higher risk for various health problems. But if she also has one or more other risk factors-doctors call them "co-morbidities"-such as hypertension or a family history of diabetes, her physician should strongly recommend that she bring her weight down and be vigilant about keeping it stable at a healthy level.

But that same woman just 15 pounds heavier is clinically obese, and at great risk for a host of major medical problems including heart disease and even cancer. Her risk of ultimately dying from those problems simply skyrockets once she reaches that 30 BMI mark.

Along with BMI, doctors also use the measurement of waist circumference. A waist circumference of more than 35 inches for women or more than 40 inches for men is considered bad news. That's because where our weight is distributed can be as critical as how much we're toting around. Weight deposited abdominally-sometimes referred to as the "apple" body type-has a much greater impact on internal organs and the way our bodies function, so it's much more dangerous than weight carried mainly on the hips and thighs, as with the "pear" body type.

How our weight is distributed is largely a result of our genetics and we don't get a vote in it. But if we end up with a body that carries weight in the torso, we get stuck with fat that is far more likely to cause elevated blood sugars and high cholesterol, that is more likely to impair kidney function, more likely to interfere with our cardiovascular health. So someone with a BMI of only 25 or 26, but with a bigger waist circumference, may be advised to lose some weight anyway, just to help avoid some of those serious health concerns.

And what of those folks who have been overweight for a long time, who are comfortable with their bodies, and so far haven't noticed any ill effects of their excess weight?

It is possible to be fit and fat, and a few people are, but it's very few. Health risks do increase with age, and you may not notice initial signs of trouble developing. But you don't have to wonder. You can find out if you're having any negative health effects because of your weight with a few simple tests conducted by your doctor to tell you if your blood sugars, cholesterol, or insulin levels are outside the healthy range.

And if they are, you know it's time to make some changes for the better, before your body takes a turn for the worse.

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